bluuebunny/crossref_metadata_2025_split huggingface dataset:
EFFECT OF HIGH SALT INTAKE ON LOCAL RENIN–ANGIOTENSIN SYSTEM AND VENTRICULAR DYSFUNCTION FOLLOWING MYOCARDIAL INFARCTION IN RATS
Authors: De Resende Micheline M , Mill José G 
Published: August 2010

SUMMARY

This study was performed to evaluate the effect of chronic high salt intake on local cardiac and renal components of the renin–angiotensin system (RAS) and its impact on cardiac remodelling and function after myocardial infarction (MI).
Rats submitted to coronary artery ligation to produce MI or sham operation (SO) were randomized to receive 1% NaCl solution or tap water as drinking water for 4 weeks. Plasma renin activity (PRA) and angiotensin‐converting enzyme (ACE) activity were quantified. Tissue angiotensin (Ang) II and ACE activity were determined by ELISA and a fluorimetric assay, respectively. Renal and cardiac AT1 and AT2 receptor protein levels were quantified by western blot.
Independent of the lower PRA levels, MI promoted a significant increase in the left ventricular/bodyweight ratio and impaired cardiac function. The cardiac RAS was activated after MI with a significant increase in ACE activity, AngII and AT1 receptor levels. The RAS was slightly attenuated under high‐salt conditions.
Interestingly, high salt intake increased the expression of the AT2 receptor by approximately twofold in the kidney of MI rats compared with the SO control group. Because of its natriuretic effect, the AT2 receptor may counterbalance the salt overload and prevent the additional impairment of cardiac function.
The present study indicates that 4 weeks after MI, high salt intake did not further increase cardiac hypertrophy or further impair cardiac function in MI rats. A chronic increase in salt intake significantly suppressed PRA, but did not prevent activation of the local RAS or the progression of cardiac remodelling and left ventricular dysfunction caused by MI.
The present results show that inhibition of systemic renin production with salt overload does not affect ventricular remodelling after MI in rats. This suggests that local activation of the RAS in the heart, which was not suppressed by salt overload, exerts a predominant role for local adaptations of the heart after MI.
SPATIAL PULMONARY FLOW DISTRIBUTION IN RABBIT ISOLATED LUNGS IS A POOR REPRESENTATION OF THE SITUATION IN VIVO*
Authors: Hübler M , Heller AR , Bleyl JU , Rössel T , Stehr SN , Koch T 
Published: August 2010

SUMMARY

Isolated lung preparations are established to investigate effects on pulmonary vascular tone and spatial pulmonary flow (Q̇rel) distribution. In the present study, we hypothesized that Q̇rel distribution in isolated lungs is only poorly correlated with the in vivo situation.
Fourteen rabbits were anaesthetized and mechanically ventilated with room air. Animals were held in an upright position for 15 min and Q̇rel was assessed using fluorescent microspheres (Q̇rel‐in vivo). A second injection of microspheres was made after isolation of the lungs (Q̇rel‐ex vivo). Lungs were dried, cut into 1 cm3 cubes and spatial Q̇rel distributions were analysed.
The mean correlation of Q̇rel‐in vivo and Q̇rel‐ex vivo was 0.592 ± 0.188 (95% confidence interval 0.493–0.690). The Q̇rel was redistributed to more ventral (the mean slope of Q̇rel vs the dorsal–ventral axis changed from −0.289 ± 0.227 to −0.147 ± 0.114; P = 0.03), cranial (mean slope of Q̇rel vs the caudal–cranial axis changed from −0.386 ± 0.193 to −0.176 ± 0.142; P < 0.001) and central (mean slope of Q̇rel vs the hilus–peripheral axis changed from 0.436 ± 0.133 to −0.236 ± 0.159; P = 0.003) lung areas.
The results obtained from studies investigating Q̇rel distributions in isolated lung models must be interpreted cautiously because the isolated lung set‐up significantly affects the spatial distribution of pulmonary flow.
MORPHOLOGICAL AND FUNCTIONAL CHANGES IN P‐GLYCOPROTEIN DURING DEXAMETHASONE‐INDUCED HEPATOMEGALY
Authors: Micuda Stanislav , Fuksa Leos , Mundlova Lucie , Osterreicher Jan , Mokry Jaroslav , Cermanova Jolana , Brcakova Eva , Staud Frantisek , Pokorna Pavla , Martinkova Jirina 
Published: August 2010

SUMMARY

The effect of dexamethasone on hepatic and renal P‐glycoprotein (P‐gp) expression, localization and activity was investigated in rats after 4 days oral administration of two dose regimens (1 or 25 mg/kg per day). Simultaneous increases in liver weight were evaluated by quantitative histological examination.
In the liver, dexamethasone pretreatment produced hepatomegaly as a consequence of extensive periportal fat accumulation, which was quantified by densitometry of oil red O‐stained liver sections. Quantitative immunohistochemical analysis revealed preferential periportal zonation of P‐gp in control animals. Dexamethasone pretreatment resulted in spatially disproportional induction of P‐gp protein expression within the liver acinus characterized by preferential increase in pericentral areas, with consequent uniform panlobular distribution. Western blot analysis confirmed these results, showing increases in P‐gp protein. Quantitative reverse transcription–polymerase chain reaction analysis revealed no statistically significant change in liver mdr1b mRNA expression after either dexamethasone treatment regimen. The expression of mdr1a mRNA was significantly decreased by 85–87%.
In the kidney, dexamethasone reduced mdr1a mRNA expression by 69–89%, whereas mdr1b mRNA expression was increased in a dose‐dependent manner. However, despite tendencies, no significant increases in P‐gp expression were observed at the protein level.
The in vivo function of P‐gp was evaluated by measuring renal and biliary secretion of rhodamine‐123 (Rho123) under a steady state plasma concentration. The biliary, renal and tubular secretory clearance of Rho123 was significantly increased only after high‐dose dexamethasone.
In conclusion, the present study suggests that drug interactions observed during corticosteroid therapy may be mediated, at least in part, through increased biliary, and also renal, excretion of P‐gp substrates. Expression of P‐gp in the liver showed primary periportal zonation with differential changes during induction. Accompanying hepatomegaly may be explained by severe microvesicular steatosis selectively localized to the periportal areas.
METHODS OF ANALYSIS AND PHYSIOLOGICAL RELEVANCE OF RHYTHMS IN SYMPATHETIC NERVE DISCHARGE
Authors: Barman Susan M , Kenney Michael J 
Published: August 2010

SUMMARY

Like virtually all other physiological control systems, the sympathetic nervous system controlling cardiovascular function is characterized by the presence of rhythmic activity. Despite the prevalence of rhythms, their function is often not obvious, which leads to the question, what can one learn about the neural control of autonomic function by studying sympathetic nervous system rhythms?
Sympathetic nerve discharge (SND) is characterized by a mixture of periodicities ranging between approximately 0.04 and 10 Hz, depending on the physiological conditions, type of nerve being analysed and the species. The present article illustrates why frequency domain (power density spectral) analysis is more suitable than time domain (autocorrelation) analysis to quantify a complex signal (i.e. one with multiple frequency components) such as SND.
The present article entertains the possibilities that rhythmic activity may lead to more effective activation of sympathetic neurons than randomly occurring activity, that rhythmicity is important for coordinating activity in different sympathetic nerves and in formulating complex cardiovascular response patterns and that sympathetic rhythmicity may help maintain homeostasis.
SYMPATHETIC RHYTHMS AND NERVOUS INTEGRATION
Authors: Gilbey Michael P 
Published: August 2010

SUMMARY

The present review focuses on some of the processes producing rhythms in sympathetic nerves influencing cardiovascular functions and considers their potential relevance to nervous integration.
Two mechanisms are considered that may account for rhythmic sympathetic discharges. First, neuronal elements of peripheral or central origin produce rhythmic activity by phasically exciting and/or inhibiting neurons within central sympathetic networks. Second, rhythms arise within central sympathetic networks. Evidence is considered that indicates the operation of both mechanisms; the first in muscle and the second in skin sympathetic vasoconstrictor networks.
Sympathetic activity to the rat tail, a model for the nervous control of skin circulation, is regulated by central networks involved in thermoregulation and those associated with fear and arousal. In an anaesthetized preparation, activity displays an apparently autonomous rhythm (T‐rhythm; 0.4–1.2 Hz) and the level of activity can be manipulated by regulating core body temperature. This model has been used to study rhythm generation in central sympathetic networks and possible functional relevance.
A unique insight provided by the T rhythm, into possible physiological function(s) underlying rhythmic sympathetic discharges is that the activity of single sympathetic post‐ganglionic neurons within a population innervating the same target can have different rhythm frequencies. Therefore, the graded and dynamic entrainment of the rhythms by inputs, such as central respiratory drive and/or lung inflation‐related afferent activity, can produce graded and dynamic synchronization of sympathetic discharges. The degree of synchronization may influence the efficacy of transmission in a target chain of excitable cells.
The T‐rhythm may be generated within the spinal cord because the intrathecal application of 5‐hydroxytryptamine at the L1 level of the spinal cord of a rat spinalized at T10–T11 produces a T‐like rhythm. Thus, induction and modulation of spinal cord oscillators may be mechanisms that influence ganglionic and neuroeffector transmission.
The study of sympathetic rhythms may not only further understanding of sympathetic control, but may also inform on the relevance of rhythmic nervous activities in general.
DIFFERENTIAL EFFECTS OF VASOPRESSINERGIC AND OXYTOCINERGIC PRE‐AUTONOMIC NEURONS ON CIRCULATORY CONTROL: REFLEX MECHANISMS AND CHANGES DURING EXERCISE
Authors: Michelini Lisete Compagno 
Published: August 2010

SUMMARY

The role of vasopressinergic and oxytocinergic (VPergic and OTergic, respectively) projections to the brain stem in the modulation of heart rate control is discussed on the basis of both changes in the peptide content of the dorsal brain stem (DBS) and functional effects following reflex‐ and exercise‐induced activation in the presence and/or absence of receptor blockade within the nucleus tractus solitarius (NTS) and/or peripheral autonomic block.
Experimental data showed a dual effect of NTS VPergic projections on reflex control: (i) to maintain tonically the reflex sensitivity; and (ii) to reset reflex bradycardia towards higher heart rate values when transiently activated. The VPergic drive causes less sympathetic inhibition during pressure increases, mainly by reducing peripheral information going to NTS second‐order neurons. Treadmill running increases the vasopressin content within the DBS. This activates NTS V1 receptors to cause a significant improvement of exercise tachycardia in both sedentary and trained rats.
The OTergic drive to DBS areas (NTS/dorsal motor nucleus of the vagus) is also tonic for baroreceptor reflex control: it improves reflex bradycardia by facilitating vagal outflow to the heart. An acute bout of exercise increases DBS oxytocin (OT) content in trained rats, causing a significant blunting of exercise tachycardia only in this group. In both sedentary and trained groups, basal heart rate varies inversely with DBS OT content, the resting bradycardia of trained rats being associated with higher OT content.
Specific coordinated activation of VPergic and OTergic suprabulbar pathways is essential to adjust heart rate and cardiac output to circulatory demand at rest and during exercise in both sedentary and trained individuals.
EXERCISE TRAINING AND SYMPATHETIC NERVOUS SYSTEM ACTIVITY: EVIDENCE FOR PHYSICAL ACTIVITY DEPENDENT NEURAL PLASTICITY
Authors: Mueller Patrick J 
Published: August 2010

SUMMARY

It has been generally accepted that regular physical activity is associated with beneficial effects on the cardiovascular system. In fact, the idea that exercise maintains cardiovascular health is evident by the direct links between a sedentary lifestyle and the risk of cardiovascular and other disease states.
Cardiovascular diseases, such as hypertension and heart failure, are often associated with sympathetic nervous system (SNS) overactivity. Conversely, exercise has been shown to reduce hypertension and decrease elevated SNS activity. In addition, there is evidence that exercise may reduce resting blood pressure and sympathetic outflow in normal individuals.
Although somewhat controversial in humans, evidence from animal studies also indicates that exercise training reduces baroreflex‐mediated and other forms of sympathoexcitation in normal individuals. Collectively, these data are consistent with the hypothesis that physical activity may decrease, and physical inactivity may increase, the incidence of cardiovascular disease via alterations in SNS activity. Despite the important clinical implications of this possibility, the mechanisms by which exercise alters control of SNS activity remain to be fully elucidated.
Recent evidence suggests that central nervous system (CNS) plasticity occurs under a variety of conditions, including varying levels of physical activity. The purpose of the present brief review is to provide evidence that changes within the CNS contribute importantly to altered regulation of the SNS observed following exercise training. The primary hypothesis is that physical activity versus inactivity produces plasticity within neural networks that regulate SNS activity. This hypothesis is supported by published and preliminary data that suggest that exercise training may reduce sympathoexcitation by reducing activation of neurons within cardiovascular regions of the brain. These mechanisms are likely to be important in disease states of sympathetic overactivity and in normal healthy individuals whose risk of cardiovascular disease is reduced by leading an active versus sedentary lifestyle.
SHRIMP U–Pb zircon chronology of ultrahigh‐temperature spinel–orthopyroxene–garnet granulite from South Altay orogenic belt, northwestern China
Authors: Li Zilong , Li Yinqi , Chen Hanlin , Santosh M. , Xiao Wenjiao , Wang Huihui 
Published: August 2010

AbstractDiagnostic mineral assemblages, mineral compositions and zircon SHRIMP U–Pb ages are reported from an ultrahigh‐temperature (UHT) spinel–orthopyroxene–garnet granulite (UHT rock) from the South Altay orogenic belt of northwestern China. This Altay orogenic belt defines an accretionary belt between the Siberian and Kazakhstan–Junggar Plates that formed during the Paleozoic. The UHT rock examined in this study preserves both peak and retrograde metamorphic assemblages and microstructures including equilibrium spinel + quartz, and intergrowth of orthopyroxene, spinel, sillimanite, and cordierite formed during decompression. Mineral chemistry shows that the spinel coexisting with quartz has low ZnO contents, and the orthopyroxene is of high alumina type with Al2O3 contents up to 9.3 wt%. The peak temperatures of metamorphism were >950°C, consistent with UHT conditions, and the rocks were exhumed along a clockwise P–T path. The zircons in this UHT rock display a zonal structure with a relict core and metamorphic rim. The cores yield bimodal ages of 499 ± 8 Ma (7 spots), and 855 Ma (2 spots), with the rounded clastic zircons having ages with 490–500 Ma. Since the granulite was metamorphosed at temperatures >900°C, exceeding the closure temperature of U–Pb system in zircon, a possible interpretation is that the 499 ± 8 Ma age obtained from the largest population of zircons in the rock marks the timing of formation of the protolith of the rock, with the zircons sourced from a ∼500 Ma magmatic provenance, in a continental margin setting. We correlate the UHT metamorphism with the northward subduction of the Paleo‐Asian Ocean and associated accretion‐collision tectonics of the Siberian and Kazakhstan–Junggar Plates followed by rapid exhumation leading to decompression.
Total knee replacement in the morbidly obese: a literature review
Authors: Samson Anthony J. , Mercer Graham E. , Campbell David G. 
Published: August 2010

AbstractBackground:  The ‘obesity epidemic’ is expected to result in an increased incidence of knee osteoarthritis and hence total knee replacements (TKRs). Reviews have demonstrated the conflicting results of TKR for all obese (body mass index (BMI) >30). The aim of this literature review was to specifically evaluate outcomes of TKR in patients with morbid obesity (MO; BMI >40).Methods:  A systematic review of medical databases (PubMed, Medline, Cochrane Library, ScienceDirect) by use of keywords from January 1990 to September 2009 was undertaken.Results:  Clinical and functional Knee Society Scores (KSS) improve after TKR for patients with MO. The post‐operative functional KSS was, in general, less than in controls. Radiographic analysis was inconclusive because of small study populations and short duration of follow‐up. All studies reporting complications noted a greater prevalence in MO patients (10–30%). Of concern was the significantly higher prevalence of deep prosthetic infection (3–9‐times that of controls). The morbidly obese also had a significantly higher incidence of wound complications. TKR did not result in weight loss for MO patients, and therefore has no benefit on weight‐related medical conditions. Bariatric surgery in MO under 65 years of age has been shown to be a cost‐effective and clinically effective method of weight reduction. This surgery also results in significant improvement in weight‐related medical conditions, the KSS and knee pain.Conclusions:  Given the increase in complications for MO patients after TKR, these patients should be advised to lose weight before surgery and, if suitable, would probably benefit from bariatric surgery.
Pancreatic solid pseudopapillary tumours – EUS FNA is the ideal tool for diagnosis
Authors: Stoita Alina , Earls Peter , Williams David 
Published: August 2010

AbstractBackground:  Solid pseudopapillary tumour (SPT) is a rare tumour of the pancreas with low malignant potential affecting mainly young women difficult to diagnose preoperatively. The aim of this study is to describe the endoscopic ultrasound (EUS) features and utility of EUS‐guided fine needle aspiration (FNA) in diagnosing these tumours.Methods:  A retrospective analysis of SPTs identified in a tertiary institution EUS database between April 2002 and April 2009 was performed. Medical records, imaging, EUS features, cytology and histology specimens were reviewed. Patients were followed up until April 2009.Results:  Seven cases of SPTs were indentified out of 2400 EUS performed. All patients were females with a mean age of 41 years (range 22–69). The tumours were solitary with a mean diameter of 2.9 cm (range 2–4.3 cm). Five tumours were located in the body and tail of the pancreas and two in the neck. All lesions were hypoechoic, heterogenous and well circumscribed, with five having a cystic component and two having a calcified rim. FNA using a 22‐gauge needle was performed in six cases with no complications. A preoperative diagnosis of SPT based on cytology was obtained in 5/6 cases (83%). Surgical resection was done in six cases with confirmation of SPT and no metastatic disease.Conclusion:  EUS‐guided FNA is a minimally invasive, safe and reliable way of diagnosing SPT by providing characteristic cytological specimens. Definitive preoperative diagnosis leads to targeted and minimally invasive surgical resection.
Outcomes of the overlay graft technique in tympanoplasty
Authors: Ryan Jennifer E. , Briggs Robert J. S. 
Published: August 2010

AbstractBackground:  This audit was undertaken to review the outcomes achieved with the overlay graft technique of tympanic membrane repair in tympanoplasty surgery.Methods:  The charts of all patients who underwent tympanoplasty, in whom an overlay graft technique of temporalis fascia tympanic membrane repair was used, between 1994 and 2007 were reviewed. Information with respect to patient demographics, presence of cholesteatoma or active infection and perforation size was documented. Details of the surgical procedure and clinical outcomes and pre‐ and post‐operative hearing thresholds were recorded in a computer database.Results:  A total of 147 overlay graft procedures were performed in 130 patients. Graft failure with reperforation occurred following five procedures, for an overall success rate of 96.6%. Eighty Type 1 tympanoplasty procedures were performed in which one failure occurred for a 98.75% success rate. Overlay grafting was combined with intact canal wall mastoidectomy (ICW) in 38 cases and with modified radical mastoidectomy (MRM) in 17 cases for a success rate of 93.8 and 95%, respectively. Delayed graft healing as a result of infection, problems such as epithelial pearl, blunting and myringitis occurred in 39 cases (26.5%). Thirty‐one cases underwent procedures for ossicular chain reconstruction, 21 of which were 2nd stage procedures. Hearing outcomes were significantly better with Type 1 tympanoplasty compared with ICW or MRM procedures.Conclusion:  This review demonstrates the overlay graft technique of tympanoplasty to be highly successful for tympanic membrane repair, particularly for the more difficult cases such as revision surgery, subtotal perforations and mesotympanic cholesteatoma.
Are there anatomical barriers to laparoscopic donor nephrectomy?
Authors: Crane Catherine , Lam Vincent W. T. , Alsakran Abdulrahman , Vasilaras Arthur , Lau Howard , Ryan Brendan , Pleass Henry C. C. , Allen Richard D. M. 
Published: August 2010

AbstractBackground:  The aim of this study was to analyse the effect of the right donor kidney and multiple arteries, on donor and recipient outcomes in the era of laparoscopic live donor nephrectomy (LLDN).Methods:  We retrospectively analysed the 200 donors and recipients who underwent a planned laparoscopic nephrectomy at two hospitals between September 1998 and December 2006. The impact of donor right kidney and multiple donor renal arteries on operative time, hospital stay, graft function, and donor and recipient complications were analysed.Results:  Of the total cohort (n = 200), 140 (70%) were classified as Simple LLDN (left live donor kidney with single renal artery). The Complex LLDN group (n = 60) contained all right‐sided kidney (n = 28) and left‐sided kidneys with multiple renal arteries (n = 32). Baseline characteristics, extraction time, conversion to open, length of admission, overall graft function and complication rates were similar between the simple and complex groups. The second warm ischaemic time in the Simple LLDN group was slightly shorter than the Complex LLDN group (32 versus 36 min P = 0.016). The 1‐month post‐operative recipient serum creatinine level was lower in the Simple LLDN group when compared with the Complex LLDN group (117 versus 125 µmol/L P = 0.025). There was no difference in post op dialysis, acute rejection within 3 months or graft survival between the Simple and Complex LLDN groups.Conclusion:  Laparoscopic procurements of right kidneys and kidneys with multiple arteries were safe and yielded kidneys with excellent function comparable with those of laparoscopic left donor nephrectomy with single artery.