bluuebunny/crossref_metadata_2025_split huggingface dataset:
Angiotensin Peptides As Neurotransmitters/ Neuromodulators In The Dorsomedial Medulla
Authors: Diz Debra I , Jessup Jewell A , Westwood Brian M , Bosch Susan M , Vinsant Sherry , Gallagher Patricia E , Averill David B 
Published: March 2003

SUMMARY1. The present review provides an update on evidence of the neurotransmitter pathways and location of receptors within the nucleus tractus solitarii (NTS) mediating the baroreflex and other haemodynamic actions of angiotensin (Ang) II.2. A series of studies suggests a significant role for substance P in the acute cardiovascular and carotid sinus chemoreceptor facilitatory actions of AngII in the NTS. The use of antisense oligonucleotides to AT1 receptors indicates both pre‐ and post‐synaptic AngII receptors are likely to be involved in these actions.3. With respect to baroreceptor reflex actions, it is clear that endogenous AngII impairs the gain for operation of the baroreceptor reflex, because AT1 receptor antagonists facilitate reflex function. This effect is either independent of substance P or involves inhibition of release. Moreover, initial data obtained using antisense oligonucleotides to AT1 receptors suggest that, in the NTS, the effect of endogenous AngII on the baroreceptor reflex is mainly due to presynaptic actions on vagal or carotid sinus afferent fibres. In contrast, the level of endogenous AngII within the NTS appears to have variable effects on activation of cardiopulmonary vagal afferent fibres by phenylbiguanide. These results indicate a divergence of effects of AngII on reflexes evoked by these two different types of sensory input.4. Use of transgenic rats with alterations in brain angiotensin peptides allowed us to assess the effect of long‐term alterations in brain Ang peptides on reflex function. We studied (mRen2)27 transgenic rats (TGR(mRen2)) with high brain medulla AngII levels and transgenic rats with angiotensinogen (Aogen) antisense linked to glial fibrillary acidic protein promoter (TGR(ASrAogen)) with greatly reduced brain Aogen. The reflex evoked by activation of cardiac vagal chemosensitive afferent fibres was enhanced in TGR(ASrAogen), whereas the baroreceptor reflex control of heart rate was attenuated in TGR(mRen2), further confirming a divergence of effects of AngII on these two sensory modalities.5. The overall results are consistent with a sustained inhibitory effect of AngII on the baroreceptor reflexes, with dose‐dependent or activation‐dependent effects on cardiac vagal afferent fibre activation. Moreover, alterations in substance P pathways may contribute to the actions of AngII on reflex function.
The Baroreflex And Beyond: Control Of Sympathetic Vasomotor Tone By Gabaergic Neurons In The Ventrolateral Medulla
Authors: Schreihofer Ann M , Guyenet Patrice G 
Published: March 2003

SUMMARY1. Barosensitive, bulbospinal neurons in the rostral ventrolateral medulla (RVLM), which provide the major tonic excitatory drive to sympathetic vasomotor neurons, are prominently inhibited by GABA.2. A major source of the GABAergic inhibition to presympathetic RVLM neurons arises from an area immediately caudal to the RVLM, known as the caudal ventrolateral medulla (CVLM).3. Arterial baroreceptor afferents projecting to the nucleus tractus solitarius (NTS) provide a major tonic excitatory input to GABAergic CVLM neurons. These CVLM cells are a critical component for baroreflex‐mediated changes in presympathetic RVLM neuronal activity, sympathetic nerve activity (SNA) and arterial pressure (AP).4. Some GABAergic CVLM neurons are tonically activated by inputs independent of arterial baroreceptors or the NTS, providing a GABAergic‐mediated inhibition of the presympathetic RVLM neurons that is autonomous of baroreceptor inputs.5. GABAergic CVLM neurons appear to play two distinct, yet important, roles in the regulation of sympathetic vasomotor tone and AP. They dampen immediate changes in AP via the baroreflex and tonically inhibit the activity of the presympathetic RVLM neurons by baroreceptor‐independent mechanisms. This baroreceptor‐independent, GABAergic inhibition of presympathetic RVLM neurons may play an important role in determining the long‐term level of sympathetic vasomotor tone and AP.
Involvement Of Oxidative Stress In Bee Venom‐Induced Inhibition Of Na+/Glucose Cotransporter In Renal Proximal Tubule Cells
Authors: Han Ho Jan , Park Soo Hyun , Lee Jang Hern , Yoon Byeong Cheol , Park Kwon Moo , Mar Woong Chon , Lee Hye Jung , Kang Sung Keel 
Published: March 2003

SUMMARY1. The present study was conducted to examine the involvement of oxidative stress in bee venom‐induced inhibition of the Na+/glucose cotransporter (α‐methyl‐d‐glucopyranoside (α‐MG) uptake), a typical functional marker of proximal tubules, in primary cultured rabbit renal proximal tubule cells (PTC).2. Bee venom (≥ 1μg/mL) increased lipid peroxide (LPO) formation over 30 min. The increase in [3H]‐arachidonic acid (AA) release and LPO formation and the inhibition ofα‐MG uptake induced by bee venom (1μg/mL) and melittin (a major component of bee venom; 0.5μg/mL) were blocked byN‐acetyl‐l‐cysteine, vitamin C and vitamin E, anti‐oxidants.3. Bee venom‐ and melittin‐induced increases in LPO formation and inhibition ofα‐MG uptake were significantly prevented by mepacrine and AACOCF3, phospholipase A2inhibitors. In addition, nordihydroguaiareic acid (a lipoxygenase inhibitor) and econazole (a cytochrome P‐450 epoxygenase inhibitor), but not indomethacin (a cyclo‐oxygenase inhibitor), prevented bee venom‐ and melittin‐induced increases in LPO formation and inhibition ofα‐MG uptake.4. Nordihydroguaiareic acid prevented bee venom‐ and melittin‐induced increases in Ca2+uptake. Moreover, anti‐ oxidants significantly prevented bee venom‐ and melittin‐induced increases in Ca2+uptake.5. In conclusion, bee venom inhibitsα‐MG uptake via the phospholipase A2–oxidative stress–Ca2+signalling cascade in primary cultured rabbit renal proximal tubule cells.
Statistical Techniques For Comparing Measurers And Methods Of Measurement: A Critical Review
Authors: Ludbrook John 
Published: March 2003

SUMMARY1. Clinical and experimental pharmacologists and physiologists often wish to compare two methods of measurement, or two measurers.2. Biostatisticians insist that what should be sought is not agreement between methods or measurers, but disagreement or bias.3. If measurements have been made on a continuous scale, the main choice is between the Altman–Bland method of differences and least products regression analysis. It is argued that although the former is relatively simple to execute, it does not distinguish adequately between fixed and proportional bias. Least products regression analysis, although more difficult to execute, does achieve this goal. There is almost universal agreement among biostatisticians that the Pearson product–moment correlation coefficient (r) is valueless as a test for bias.4. If measurements have been made on a categorical scale, unordered or ordered, the most popular method of analysis is to use the kappa statistic. If the categories are unordered, the unweighted kappa statistic (K) is appropriate. If the categories are ordered, as they are in most rating scales in clinical, psychological and epidemiological research, the weighted kappa statistic (Kw) is preferable. But Kw
corresponds to the intraclass correlation coefficient, which, like r for continuous variables, is incapable of detecting bias. Simple techniques for detecting bias in the case of ordered categorical variables are described and commended to investigators.
Caffeine Decreases The Expression of Na+/K+‐Atpase and the Type 3 Na+/H+ Exchanger In Rat Kidney
Authors: Lee JongUn , Ha Jeong Hoon , Kim Sunmi , Oh YoonWha , Kim Soo Wan 
Published: March 2003

SUMMARY1. The aim of the present study was to explore the mechanisms underlying the renal effects of caffeine.2. Male Sprague‐Dawley rats were treated with caffeine, consisting of a single oral bolus (0.2%, 20 mL/kg) followed by supplementation in drinking water (0.2%) for 1 day. Rats treated the same but given water without caffeine served as controls.3. The expression of α1‐ and β1‐subunits of Na+/K+‐ATPase,
the type 3 Na+/H+ exchanger (NHE3) and aquaporin‐1 was determined in the kidney by western blot analysis.4. To explore possible involvement of local humoral mediators, the tissue expression of nitric oxide synthase (NOS) proteins was determined by western blot analysis and the expression of atrial natriuretic peptide (ANP) mRNA was determined by semiquantitative reverse transcription–polymerase chain reaction.5. Following treatment with caffeine, the expression of α1‐ and β1‐subunits
of Na+/K+‐ATPase, as well as that of NHE3, was decreased. Accordingly,
the catalytic activity of Na+/K+‐ATPase was decreased. In contrast, the expression of aquaporin‐1 was not altered significantly.6. The expression of the endothelial isoform of NOS was increased, along with tissue nitrite/nitrate levels. The expression of ANP mRNA was increased.7. It is suggested that caffeine decreases Na+/K+‐ATPase and NHE3 activities and increases nitric oxide and ANP activities in the kidney.
Cellular Signalling In Arteriolar Myogenic Constriction: Involvement Of Tyrosine Phosphorylation Pathways
Authors: Murphy Timothy V , Spurrell Brian E , Hill Michael A 
Published: March 2003

SUMMARY1. An increase in transmural pressure in arterioles results in a shortening of vascular smooth muscle cells, with subsequent constriction of the vessel. The mechanisms underlying this myogenic contraction are not fully understood; however, the obligatory role of increases in intracellular [Ca2+] and myosin light chain phosphorylation have been demonstrated.2. The myogenic response shows a relationship with smooth muscle cell membrane potential and influx of extracellular Ca2+ through voltage‐operated
Ca2+ channels (VOCC). Mechanically sensitive channels and possibly
release of Ca2+ from intracellular stores may play a role. However,
there are other components of myogenic contraction that cannot be explained by a
Ca2+–MLCK mechanism, for example the initial sensing of
alterations in transmural pressure, whether sustained myogenic constriction involves
myofilament Ca2+ sensitization or remodelling of the vessel wall in response to a maintained increase in transmural pressure.3. In an attempt to investigate these areas, recent studies have examined a role for tyrosine phosphorylation pathways in pressure‐induced contraction of arterioles. In rat pressurized cremaster arterioles, tyrosine kinase inhibitors dilated vessels showing spontaneous myogenic tone and tyrosine phosphatase inhibitors caused vasoconstriction. However, pressure‐induced myogenic constriction of vessels persisted in the presence of these agents. Biochemical studies revealed that phosphotyrosine formed at a relatively slow rate (significant after 5 min, with maximal increase after approximately 15 min) in response to increased vessel transmural pressure, in contrast with myosin light chain phosphorylation or the time‐course of myogenic constriction itself (maximum within 1 min).4. Taken together, these observations support the idea of a role for tyrosine phosphorylation pathways in longer‐term responses to increased transmural pressure rather than acute myogenic constriction. Phosphotyrosine formation was also more closely correlated to vessel wall tension (pressure × diameter) than the diameter of the arterioles alone. The identity of the tyrosine‐phosphorylated proteins requires further investigation; however, there is some evidence supporting roles for cSrc‐type tyrosine kinases and p44 mitogen‐activated protein kinase. The longer‐term responses of blood vessels to increased transmural pressure that may involve tyrosine phosphorylation pathways include maintenance of myogenic constriction and vessel wall remodelling.
Effect of calcium on the vascular contraction induced by cobra venom cardiotoxin
Authors: Kwan CY , Kwan TK , Huang SJ 
Published: March 2003

Summary1. The cytotoxic effects of cardiotoxin (CTX) purified from Cobra venom were tested in endothelium‐denuded rat aortic ring preparations in tissue organ baths and the effect of extracellular Ca2+ on the cytotoxic effect of CTX was investigated using a digital dynamic calcium imaging technique.2. At 10 µmol/L, CTX induced a slowly developing and sustained contraction that amounted to approximately 50% of the maximal contraction induced by 80 mmol/L KCl. At high concentrations (> 15 µmol/L), CTX caused irreversible damage to the smooth muscle contractile function. However, washout of CTX at its peak contraction did not affect the subsequent contraction to either KCl or phenylephrine.3. Contraction induced by CTX was dependent on the Ca2+concentration in the external solution. A maximal contractile response to CTX was obtained in medium containing 1–2.5 mmol/L Ca2+. This contractile response induced by CTX decreased with higher Ca2+ concentrations and was completely diminished when 7 mmol/L Ca2+, 3 mmol/L Ni2+ or 30 µmol/L tetrandrine (a non‐selective calcium channel blocker) was present in the external solution before addition of CTX to the bath.4. The above observations were supported by the calcium imaging work performed with cultured aortic smooth muscle cells from Wistar‐Kyoto rats, in which CTX was shown to induce the elevation of cytosolic Ca2+ in the presence, but not in the absence, of 2.5 mmol/L extracellular Ca2+. Increasing the extracellular Ca2+ concentration to 7 mmol/L, the addition of 3 mmol/L Ni2+ or inclusion of 30 µmol/L tetrandrine inhibited the elevation of cytosolic Ca2+ induced by CTX.5. These results suggest that: (i) a CTX‐sensitive internal calcium store does not exist in rat aortic smooth muscle; (ii) the contractile effect CTX is associated with a Ca2+ influx process; and (iii) CTX interacts extracellularly with the plasma membrane at the level of the calcium channels, as well as anionic sites to which Ca2+ and other inorganic cations bind.
Regulation of K+ channels underlying the slow afterhyperpolarization in enteric afterhyperpolarization‐generating myenteric neurons: Role of calcium and phosphorylation
Authors: Vogalis Fivos , Harvey John R , Neylon Craig B , Furness John B 
Published: March 2003

Summary1. Myenteric afterhyperpolarization‐generating myenteric (AH) neurons serve as intrinsic primary afferent neurons of the enteric nervous system and generate prolonged or slow afterhyperpolarizing potentials (slow AHP). The slow AHP is generated by an increase in a Ca2+‐activated K+ conductance (gK‐Ca) and is inhibited by enteric neurotransmitters leading to increased excitability.2. Using cell‐attached patch‐clamp recordings from AH neurons, we have shown that K+ channels with an intermediate unitary conductance (IK channels) open following action potential firing.3. In excised patches from AH neurons, we have identified an IK‐like channel that can be activated by submicromolar levels of cytoplasmic Ca2+ and is not voltage dependent.4. Application of the catalytic subunit of cAMP‐dependent protein kinase to the cytoplasmic surface of inside‐out patches inhibits the opening of IK‐like channels previously activated by Ca2+.5. The IK‐like channels are resistant to external tetraethylammonium (5 mmol/L) and apamin (0.3–1 µmol/L), but are inhibited by clotrimazole (10 µmol/L).6. Our present data support the idea that an increase in the open probability of IK‐like channels in AH neurons following an increase in cytoplasmic [Ca2+] is responsible for the slow AHP and their opening is modulated by kinases.
Restoration of arterial baroreflex function contributes to organ protection in spontaneously hypertensive rats treated with long‐term hydrochlorothiazide mixture
Authors: Lu Ze‐An , Xie He‐Hui , Xu Li‐Ping , Yin An‐Fan , Miao Chao‐Yu , Su Ding‐Feng 
Published: March 2003

Summary1. Hydrochlorothiazide mixture (HCTM) is widely used in China for the treatment of hypertension. This mixture consists of hydrochlorothiazide, triamterene, reserpine, hydralazine and chlordiazpoxide, with small (one‐third to one‐fifth of normal) doses of each drug. The present study was designed to investigate the effects of this mixture on blood pressure, blood pressure variability (BPV), baroreflex sensitivity (BRS) and end‐organ damage in spontaneously hypertensive rats (SHR).2. The HCTM was mixed in the rat chow and rats were treated for 4 months. After treatment, rats were catheterized and their blood pressure, BPV and BRS were measured in the conscious state. Organ damage was examined after these measurements had been completed.3. It was found that HCTM not only decreased blood pressure and BPV, but also ameliorated impaired BRS in SHR. The HCTM had an obvious effect on organ protection in SHR.4. The HCTM prevented left ventricular hypertrophy and this effect was mainly related to a decrease in systolic blood pressure. The effects of HCTM on preventing renal atrophy were mainly determined by BRS. Baroreflex sensitivity was the most important determinant for predicting organ damage in HCTM‐treated SHR.5. In conclusion, long‐term treatment of rats with HCTM prevented hypertensive organ damage. Restoration of arterial baroreflex function contributes to organ protection in SHR treated in the long term with HCTM.
Synergism between β2‐adrenoceptor agonists and subtype‐selective α1A‐adrenoceptor antagonists in the tocolytic effect on pregnant rat uterus in vitro
Authors: Mihályi A , Gáspár R , Csonka D , Falkay G 
Published: March 2003

Summary1. Despite great efforts in recent decades, premature birth is still a leading cause of perinatal morbidity and mortality. β2‐Adrenoceptor agonists are frequently used as tocolytics, although their use is rather controversial. Previous animal studies have revealed that blockade of α1A‐adrenoceptors results in relaxation of the pregnant rat myometrium.2. The aim of the present study was to investigate the uterus relaxant effect of the β2‐adrenoceptor agonists (terbutaline, ritodrin) applied together with the subtype‐selective α1A‐adrenoceptor antagonists (WB 4101, 5‐methylurapidil) in an in vitro rat model. The main objective of the experiments was to clarify whether there was an additive or a potentiating synergism between the two drug classes.3. Myometrial rings were taken from female, 22‐day pregnant (end‐term) Sprague‐Dawley rats. Electrical field stimulation (EFS) was used to elicit rhythmical contractions. Non‐cumulative concentration–response curves were constructed to the β2‐adrenoceptor agonists and the α1A‐adrenoceptor antagonists alone and to β2‐adrenoceptor agonists co‐administered with the α1A‐adrenoceptor antagonists.4. Both groups of drugs inhibited EFS‐induced contractions in a dose‐dependent way. Administering the β2‐adrenoceptor agonists in combination with the α1A‐adrenoceptor antagonists resulted in a significant decrease in the EC50 and an increase in the maximal contraction inhibiting effect.5. The potentiating synergism that has been revealed between β2‐adrenoceptor agonists and α1A‐adrenoceptor antagonists in the uterus relaxant effect may be of great clinical importance because it could improve the efficacy of therapy of preterm delivery.
Prevalence of overweight and hypertension in Tanzania: Special emphasis on resting energy expenditure and leptin
Authors: Kuga Sachiko , Njelekela Marina , Noguchi Takanori , Kanda Tomo , Yamori Masashi , Sato Toshiaki , Miki Tomohiro , Ikeda Katsumi , Nara Yasuo , Mtabaji Jacob 
Published: March 2003

Summary1. In the present study we investigated the difference in the distribution of selected cardiovascular disease risk factors among three middle‐aged Tanzanian populations with different lifestyles.2. The prevalence of hypertension and overweight was higher in urban areas than in rural areas. Plasma leptin concentration was also highest in urban areas. Based on these results, we speculated that overweight in the urban population may be partly due to adiposity.3. Resting energy expenditure was lower in urban areas than in other areas for both genders. These findings suggest that the high prevalence of overweight in the urban population may be partly due to low physical activity levels.
Austro‐oriental genus Parabaliothrips Priesner (Thysanoptera: Thripidae), with a new Australian species forming male aggregations
Authors: Gillespie Peter S , Mound Laurence A , Wang Chin‐Ling 
Published: March 2003

AbstractA second Australian species of Parabaliothrips Priesner is described, P.
newmani, forming male aggregations on the leaf buds of Moreton Bay fig, Ficus
macrophylla (Moraceae). The genus, predominantly south‐east Asian, is redefined
and a key provided to the five described species. Members of this genus feed on leaves
across a wide range of plant families, although each species is host specific. The
host plant of the previously known Australian species, P. setifer Karny, is
newly recognised as Leucopogon lanceolatus (Epacridaceae), and different south‐east Asian species are associated with species of Betulaceae, Hamamelidaceae and Fagaceae.
Intravenous regional anaesthesia in the treatment of paediatric forearm fractures in the emergency department
Authors: Ojala Rob , Kelly Anne‐Maree 
Published: March 2003

Abstract Objective: To describe our experience using local anaesthetic‐assisted manipulation and plaster with prilocaine as a method of facilitating fracture reduction in paediatric patients; in particular, issues of efficacy and safety. Methods: Retrospective explicit chart review was performed on all paediatric patients presenting with distal forearm fractures for a 6 month period between 1 January and 31 July 1996. Data collected included: (i) the success of the procedure (defined by clinical and radiological parameters); (ii) age and gender of the patient; (iii) use of adjuvant medications; and (iv) occurrence of complications. Results: In the study period, 156 paediatric patients presented with distal forearm fractures. Of these, 78 patients required manipulation. Fifty‐three patients were treated with a local anaesthetic‐assisted manipulation and plaster, while 25 patients were admitted for a reduction under general anaesthesia. Successful fracture reduction using local anaesthetic‐assisted manipulation and plaster was achieved in 96.3% of the cases in which this method was used. With respect to safety, no adverse respiratory/haemodynamic sequelae or problems with prilocaine toxicity were found. Adjuvant medication was used frequently (49%); however, the reasons for use could not be determined in this study. Conclusions: This study suggests that local anaesthetic‐assisted manipulation and plaster using prilocaine has a high success rate and a good safety record. This should be confirmed by study of a larger population. Factors to be taken into account when considering the use of this procedure are: (i) patient and parental preference; (ii) age of the patient; (iii) experience of the available staff; (iv) availability of personnel resources; (v) impact on patient flow in the emergency department; and (vi) anticipated delay in therapy if admission for treatment under general anaesthesia is chosen.