bluuebunny/crossref_metadata_2025 huggingface dataset:
Non‐Invasive Single Cell pH Measurements In The Isolated Perfused Pancreas
Authors: Mooren Frank C , Domschke Wolfram , Kinne Rolf Kh , Gronczewski Jacek , Lerch Markus M
Published: March 2003

1. A new method was developed for non‐invasive investigations of intracellular pH (pHi) regulation in different cell types of the isolated perfused pancreas using a confocal laser scanning technique.

2. After removal of the rat pancreas the coeliac artery was cannulated and the splenic segment of the pancreas was perfused with dextran (5%)–Ringer solution at a constant flow rate of 2 mL/min. In a temperature‐controlled (37°C) chamber, pH regulation was studied using the pH‐sensitive fluorescent dye 2′,7′‐bis‐(2‐carboxyethyl)‐5‐(‐6)‐carboxyfluorescein (BCECF) with a confocal microscope (MRC‐600; Bio‐Rad, Hercules, CA, USA).

3. Image analysis permitted the identification and comparison of different cell types with a pHi of 7.26±0.1 in acinar cells and of 7.02±0.1 in endothelial cells. Increasing PCO2 from 5 to 20% resulted in a rapid decrease in pHi. Omission of sodium from the perfusate resulted in a smooth decline in pHi. Both decreases were found to be fully reversible. Increasing PCO2 under sodium‐free conditions also resulted in a drop of pHi that was, however, not fully reversible, suggesting involvement of the Na+/H+ exchanger in the regulation of pHi in the intact organ.

4. The above method completely preserves tissue integrity and, therefore, allows the study of pH regulation in different cell types of the pancreas simultaneously and without interference with their functional arrangement. The technique should be of specific value to investigate experimental disease states of the pancreas.
Fibroblast Growth Factors In The Developing Central Nervous System
Authors: Ford‐Perriss Miriam , Abud Helen , Murphy Mark
Published: March 2003

1. It is now clear that members of the fibroblast growth factor (FGF) family have multiple roles during the formation of the central nervous system (CNS).

2. There are at least 23 members of the FGF family and, of these, 10 are expressed in the developing CNS, along with four FGF receptors (FGFR‐1–4).

3. The present review discusses the roles of these FGFs, with emphasis on FGF‐2, FGF‐8, FGF‐15 and FGF‐17. Fibroblast growth factors‐2 and ‐15 are generally expressed throughout the developing CNS, whereas FGF‐8 and FGF‐17 are tightly localized to specific regions of the developing brain and are only expressed in the embryo during the early phases of proliferation and neurogenesis.

4. Expression studies on FGFRs in the chick and mouse indicate that FGFR‐1 is most generally expressed, whereas FGFR‐2 and FGFR‐3 show highly localized but changing patterns of expression throughout CNS development. The FGFR‐4 has been localized to the developing CNS in fish but not at a detailed level, as yet, in chick or mouse.

5. A picture is emerging from these studies that particular FGFs signal through specific receptors in a highly localized manner to regulate the development of different regions of the brain.

6. This picture has been demonstrated so far for the developing cortex (FGF‐2–/– mice), the forebrain and midbrain (FGF‐8 hypomorphs) and the cerebellum (FGF‐17/FGF‐8 mutant mice). In addition, generation of mutant animals deleted for FGFR‐1 and FGFR‐2b IIIb demonstrate their importance in FGF signalling.

7. However, there are significant gaps in our knowledge of the localization of members of the FGF family and their receptors. More detailed information on the spatio‐temporal mapping of FGFs and FGFR isoforms is required in order to understand the molecular mechanisms through which FGFs signal.
Airway Protection Following Simulated Gastro‐Oesophageal Reflux In Sedated And Sleeping Neonatal Piglets During Active Sleep
Authors: McKelvey George M , Post Elizabeth J , Wood Andrew Kw , Jeffery Heather E
Published: March 2003

1. In infants, promethazine has been implicated in the pathogenesis of sleep apnoea, apparent life threatening events (ALTE) and the Sudden Infant Death syndrome (SIDS). The aim of the present study was to investigate, in a neonatal animal, the effects of a commonly used promethazine‐containing medication on airway protective mechanisms and cardiorespiratory reflexes following simulated gastro‐oesophageal reflux (GER) to different levels in the oesophagus and pharynx.

2. Physiological and radiographic recordings were made in 21 naturally sleeping (controls) and 21 sedated (1.5 mg/kg, p.o., promethazine) piglets. On 3 consecutive days physiological recordings were made in all piglets during active sleep. Gastro‐oesophageal reflux was simulated by the injection of boluses of 0.5 mL HCl, pH 2 or 3, or NaCl (0.9%) at 37°C into the pharynx, upper or lower oesophagus.

3. In healthy neonatal piglets, minimal sedation with promethazine, which did not affect behaviour during wakefulness, revealed previously unreported findings during active sleep.

4. The most significant effects were observed following simulated GER to the pharynx, with no effect observed in the lower oesophagus. In sedated piglets, compared with naturally sleeping piglets, there was a significant reduction in swallowing (P < 0.01), delayed radiological clearance of fluid (P < 0.05), a reduction in breathing rate, oxygen saturation and heart rate and an increase in apnoea.

5. These findings are consistent with a low dose of promethazine producing a significant attenuation of airway protective mechanisms and, thus, stimulation of the laryngeal chemoreflex. The results suggest a mechanism for the association observed between promethazine use and the occurrence of ALTE and SIDS. The results support continued caution and suggest the need for greater regulation of promethazine‐containing medications in infants.
Circumventricular Organs: Gateways to the BrainMultisynaptic Neuronal Pathways From The Submandibular And Sublingual Glands To The Lamina Terminalis In The Rat: A Model For The Role Of The Lamina Terminalis In The Control Of Osmo‐ And Thermoregulatory Behaviour
Authors: Hübschle Thomas , Mathai Michael L , McKinley Michael J , Oldfield Brian J
Published: March 2003

1. The putative regulatory role of the lamina terminalis in the central control of salivation was investigated in the rat using the viral‐tracing technique and Fos‐immunohistochemistry.

2. Neurons situated in the lamina terminalis, such as the vascular organ of the lamina terminalis (OVLT), median preoptic nucleus (MnPO) and subfornical organ (SFO), were retrogradely labelled after pseudorabies virus injections into the submandibular or sublingual gland.

3. Viral tracing combined with glandular denervation showed that lamina terminalis structures sent efferents, in particular, to the parasympathetic side of submandibular gland innervation.

4. Saliva lost under heat stress has severe implications for the body fluid economy of rats and a key to the understanding of the central regulation of heat‐induced salivation may be the integrative role of the lamina terminalis processing thermoregulatory and osmoregulatory information.
Effects of adenosine administration on spike‐wave discharge frequency in genetically epileptic rats
Authors: Ilbay Gul , Sahin Deniz , Karson Ayse , Ates Nurbay
Published: March 2003

1. In the present study, the effects of the administration of adenosine on absence seizures were investigated in the Wistar Albino Glaxo/Rijswijk (WAG/Rij) strain of rats, which are an adequate model for human absence epilepsy.

2. After baseline electroencephalogram (EEG) recording, adenosine was injected intraperitonealy (i.p.) at doses of 6, 30 and 120 mg/kg and EEG recordings were continued for 1 h postinjection. In addition, to enable evaluation of the contribution of peripheral factors to the occurrence of spike‐wave discharges (SWD) after adenosine injection, arterial blood pressure and rectal temperature were also recorded.

3. Injection of adenosine induced a dose‐dependent increase in the appearance of SWD. The number and total duration of SWD were found to be significantly increased after 30 and 120 mg/kg adenosine (P < 0.05). Adenosine also induced a fall in both blood pressure and body temperature in all experimental groups.

4. These results show that peripheral administration of adenosine promotes absence seizures. It is likely that the lowering of blood pressure and body temperature and the activation of sensory afferents after adenosine injection may contribute to the facilitation of SWD observed in the present study.
Protein Kinase C and Changes In Manganese Superoxide Dismutase Gene Expression In Cultured Glial Cells
Authors: Huang Wei‐Chien , Chen Pei‐Chi , Jou Shou‐Bin , Cheng Juei‐Tang
Published: March 2003

1. To study the role of protein kinase C (PKC) in the increase in manganese superoxide dismutase (Mn‐SOD) gene expression following transient hypoxia in glial cells, we examined the mRNA levels of Mn‐SOD using northern blot analysis.

2. The Mn‐SOD mRNA levels were markedly increased after exposure to nitrogen gas for 5 min.

3. Pretreatment with chelerythrine or GF109203x, inhibitors of PKC, attenuated the increase in Mn‐SOD mRNA following hypoxia in a concentration‐dependent manner.

4. Incubation with phorbol 12‐myristate 13‐acetate, the PKC activator, enhanced the increase in Mn‐SOD gene expression in response to transient hypoxia.

5. The results suggest that hypoxia increases Mn‐SOD gene expression in cultured glial cells mainly through activation of a PKC pathway.
Role Of Protein Kinase C In Myogenic Calcium– Contraction Coupling Of Rat Cannulated Mesenteric Small Arteries
Authors: Wesselman Jos Pm , Spaan Jos AE , Meulen Esther T van der , VanBavel Ed
Published: March 2003

1. The present study was designed to determine the role of protein kinase C (PKC) in the myogenic response of small arteries. In particular, we tested whether inhibition of PKC reverses the previously found pressure‐induced elevation of contractile element calcium sensitivity.

2. Rat mesenteric small arteries were cannulated and pressurized. The internal diameter was continuously monitored with a video camera and intracellular calcium levels were measured by means of fura‐2. Myogenic responses were observed when the pressure was raised stepwise from 20 to 60 and then to 100 mmHg in physiological saline solution and during application of phenylephrine (0.1 or 1 μmol/L) or potassium (36 mmol/L).

3. The PKC inhibitors H‐7 (20 μmol/L), staurosporine (100 nmol/L) and calphostin C (10 nmol/L) all completely abolished the myogenic response. Whereas staurosporine caused an ongoing reduction in intracellular calcium, pressure‐induced calcium transients were not affected by either H‐7 or calphostin C. In particular, the slope of the wall tension–calcium relationship remained similar in the presence of both H‐7 and calphostin C, despite an upward shift of this relationship to higher calcium levels in the case of calphostin C.

4. These results show that activity of PKC isoform(s) is essential for myogenic calcium–contraction coupling.
Cerebrovascular Dysfunction After Subarachnoid Haemorrhage: Novel Mechanisms And Directions For Therapy
Authors: Sobey Christopher G
Published: March 2003

1. When a cerebral aneurysm ruptures, bleeding and clot formation occur around the surface of the brain, including several major blood vessels. The resulting condition, known as subarachnoid haemorrhage (SAH), often results in death or severe disability and is a significant cause of stroke. Delayed cerebral vasospasm and impaired vasodilatation are critical clinical complications that occur after SAH. Mechanisms contributing to the development of vasospasm and abnormal reactivity of cerebral arteries after SAH have been intensively investigated in recent years. The present short review briefly decribes recent advances in our knowledge of two relatively novel aspects of the mechanism(s) underlying the vascular abnormalities following SAH.

2. Cerebral arteries are depolarized after SAH, possibly due to decreased activity of potassium channels in vascular muscle. Decreased basal activation of potassium channels may be due to several mechanisms, including impaired activity of nitric oxide (NO). Vasodilator drugs that produce hyperpolarization, such as potassium channel openers, appear to be particularly effective for dilating cerebral arteries after experimental SAH.

3. Subarachnoid haemorrhage often involves decreased responsiveness of cerebral arteries to NO. This could be due to impaired activity of soluble guanylate cyclase, resulting in reduced basal levels of cGMP in cerebral vessels. However, an alternative explanation is that there may be an increased rate of cGMP hydrolysis by phosphodiesterase (PDE)‐V in the cerebral vascular wall and that this abnormality contributes substantially to the impairment of NO‐mediated cerebral vasodilatation after SAH. In support of this proposal, vasodilator responses to NO are reported to be normalized when coadministered with a PDE‐V inhibitor following experimental SAH.

4. Thus, in cerebral vascular muscle after SAH, abnormalities of vasodilator mechanisms involving potassium channel function and also NO/cGMP activity may contribute to cerebral vascular dysfunction. These mechanisms may also represent useful and novel therapeutic targets for the treatment of vasospasm.
A Hypothesis About A Mechanism For The Programming Of Blood Pressure And Vascular Disease In Early Life
Authors: Martyn Cn , Greenwald Se
Published: March 2003

1. There is now a great deal of evidence that people whose weight at birth was low tend to have higher blood pressure and increased risk of death from cardiovascular disease as adults.

2. We argue that, in fetuses whose growth is impaired, synthesis of elastin in the walls of the aorta and large arteries is deficient and that this deficiency leads to permanent changes in the mechanical properties of these vessels.

3. Over a lifetime, such changes could predispose an individual to higher blood pressure and cardiovascular disease.
Sympathetic Nerve Biology In Essential Hypertension
Authors: Esler Murray , Rumantir Magdalena , Kaye David , Jennings Garry , Hastings Jacqui , Socratous Flora , Lambert Gavin
Published: March 2003

1. Although the importance of sympathetic nervous activation in the pathogenesis of essential hypertension is well documented, the exact pathophysiology of the sympathetic nervous dysfunction present remains to be delineated. There are several possible explanations for the increased spillover of noradrenaline from the kidneys and heart to plasma, a key piece of evidence supporting the neurogenic basis of essential hypertension, in addition to the obvious one of an increased rate of sympathetic nerve firing.

2. The possibility that there may be an increase in the density of sympathetic innervation in human hypertension, well documented in the spontaneously hypertensive rat, is currently under investigation by us.

3. Adrenaline cotransmission is present in the cardiac sympathetic nerves of patients with essential hypertension, presumptive evidence of their exposure to high levels of stress and a possible basis for the observed increase in cardiac noradrenaline spillover, through presynaptic augmentation of noradrenaline release.

4. Phenotypic evidence exists also of faulty noradrenaline reuptake into the sympathetic nerves of the heart in essential hypertension, an abnormality that would amplify the sympathetic neural signal by impairing removal of noradrenaline from the synaptic cleft.
New Elements In Human Renin Promoter Involved In Cell‐Specific Expression
Authors: Germain Stéphane , Fuchs Sébastien , Philippe Josette , Corvol Pierre , Pinet Florence
Published: March 2003

1. The renin–angiotensin system plays a major role in blood pressure regulation and electrolyte homeostasis through the action of angiotensin (Ang) II. The first and rate‐limiting step in the production of AngII is the conversion of angiotensinogen into AngI, which is catalysed by the aspartyl protease renin (EC 3.4.23.15). Circulating active renin is mainly synthesized, processed and secreted by the juxtaglomerular cells within the kidney.

2. To determine the renin 5′‐flanking sequences involved in cell and tissue specificity, ex vivo and in vivo studies were performed. Several constructs of various lengths of renin promoter linked to the luciferase gene were first tested ex vivo by transfection in primary cultures of human chorionic cells. The constructs giving a high and specific expression in renin‐producing cells were then tested in vivo in a transgenic mice model.

3. The reporter gene chosen to generate transgenic mice was LacZ and the screening was performed in embryos at the embryonic day (E) 15 stage, at which mouse renin is expressed in the developping vessels of the kidney.

4. Only constructs containing more than 5.7 kb of the human renin promoter lead to specific expression of β‐galactosidase in the kidney.

5. Our results demonstrate that the human renin distal promoter region allows a more restricted expression of LacZ in the renin‐expressing cells in transgenic mice.
Paring Down On Descartes: A Review Of Brain Noradrenaline And Sympathetic Nervous Function
Authors: Lambert Gavin W
Published: March 2003

1. The conceptual framework of mind–body interaction can be traced back to the seminal observations of the French philosopher and mathematician René Descartes (1596–1650). Descartes succeeded in eliminating the soul’s apparent physiological role and established the brain as the body’s control centre.

2. While the pivotal role played by the central nervous system (CNS) in the maintenance of physiological and psychological health has long been recognized, the development of methods designed for the direct examination of human CNS processes has only recently come to fruition.

3. There exists a substantial body of evidence derived from clinical and experimental studies indicating that CNS monoaminergic cell groups, in particular those using noradrenaline as their neurotransmitter, participate in the excitatory regulation of the sympathetic nervous system and the development and maintenance of the hypertensive state.

4. In essential hypertension, particularly in younger patients, there occurs an activation of sympathetic nervous outflows to the kidneys, heart and skeletal muscle. The existence of a correlation between subcortical brain noradrenaline turnover and total body noradrenaline spillover to plasma, resting blood pressure and heart rate provides further support for the observation that elevated subcortical noradrenergic activity subserves a sympathoexcitatory role in the regulation of sympathetic preganglionic neurons of the thorocolumbar cord.
‘Slow Pressor’ Hypertension From Low‐Dose Chronic Angiotensin II Infusion
Authors: Edgley AJ , Kett MM , Anderson WP
Published: March 2003

1. Angiotensin (Ang) II causes growth‐related effects on vascular smooth muscle cells in vitro and in vivo.

2. Chronic infusions of AngII systemically, at doses that are initially subpressor, result in slowly progressive increases in arterial pressure (‘slow‐pressor’ hypertension). It has been suggested that the hypertension is due to induced growth in systemic resistance vessel walls by the AngII infusions.

3. We report the results of several studies investigating whether there are also induced structural changes in renal resistance vessels during chronic AngII infusions. We have developed models in Sprague‐Dawley rats in which low‐dose AngII infusions, either into the renal artery (thus restricting the effects to the kidney) or systemically, result in hypertension.

5. In both models, we have evidence suggesting that chronic AngII infusions have resulted in apparent structurally induced reductions in renal vasculature lumen upstream to the glomerulus.

6. The role of these renal changes in the development of the hypertension remain to be determined.
Exercise And Skeletal Muscle Gene Expression
Authors: Cameron‐Smith David
Published: March 2003

1. Skeletal muscle is a complex and heterogenous tissue capable of remarkable adaptation in response to exercise training. The role of gene transcription, as an initial target to control protein synthesis, is poorly understood.

2. Mature myofibres contain several hundred nuclei, all of which maintain transcriptional competency, although the localized responsiveness of nuclei is not well known. Myofibres are capable of hypertrophy. These processes require the activation and myogenic differentiation of mononuclear satellite cells that fuse with the enlarging or repairing myofibre.

3. A single bout of exercise in human subjects is capable of activating the expression of many diverse groups of genes.

4. The impact of repeated exercise bouts, typical of exercise training, on gene expression has yet to receive systematic investigation.

5. The molecular programme elicited by resistance exercise and endurance exercise differs markedly. Muscular hypertrophy following resistance exercise is dependent on the activation of satellite cells and their subsequent myogenic maturation. Endurance exercise requires the simultaneous activation of mitochondrial and nuclear genes to enable mitochondrial biogenesis.

6. Future analysis of the regulation of genes by exercise may combine high‐throughput technologies, such as gene‐chips, enabling the rapid detection and analysis of changes in the expression of many thousands of genes.
Mitochondrial Proteins In Hypertrophy And Atrophy: A Transcript Analysis In Rat Heart
Authors: Taegtmeyer Heinrich , Razeghi Peter , Young Martin E
Published: March 2003

1. Metabolic processes are acutely and chronically regulated in response to changes in the workload of the heart. Acute changes in cardiac work result in activation and inactivation of existing enzymes and in altered fluxes through existing metabolic pathways. Sustained or chronic changes in cardiac work result in both trophic and transcriptional alterations.

2. The metabolic consequences of a sustained increase or decrease in the workload of the heart are surprisingly uniform and consist of a switch from the predominant oxidation of fatty acids to oxidation of glucose.

3. This switch is reflected in the changes of the transcript levels of three key regulators of mitochondrial function: pyruvate dehydrogenase kinase 4 (PDK4), which phosphorylates and inactivates the pyruvate dehydrogenase complex, malonyl‐CoA decarboxylase (MCD), which regulates malonyl‐CoA levels and, therefore, rates of β‐oxidation of long‐chain fatty acids, and uncoupling protein 3 (UCP‐3), which uncouples the oxidative phosphorylation of ADP.

4. The transcript levels of all three proteins are downregulated in hypertrophy as well as in atrophy of rat heart. All three transcripts are transcriptionally regulated by the nuclear receptor peroxisome proliferator‐activated receptor α
(PPARα).

5. Diminished expression of PPARα and PPARα‐regulated
genes constitutes an adaptive mechanism in response to altered workload, because
reactivation of PPARα in hypertrophied heart results in severe contractile dysfunction.
Glutamate Circuits In Selected Medullo‐Spinal Areas Regulating Cardiovascular Function
Authors: Sapru HN
Published: March 2003

1. The importance of the medullo‐spinal neuronal pools in the regulation of cardiovascular function has been known for a long time. However, important groups of these neurons, interconnections between them and the neurotransmitters released at their projections have been identified with certainty only during the past two decades.

2. Some of the medullo‐spinal neuronal pools mediating cardiovascular function include the nucleus tractus solitarius, caudal ventrolateral medullary depressor area, rostral ventrolateral medullary pressor area, nucleus ambiguus and intermediolateral cell column of the thoracolumbar spinal cord. Interactions between these selected neuronal groups and neurotransmitters in the pathways connecting them are discussed in the present short review.
Role Of Excitatory Amino Acid Inputs To The Rostral Ventrolateral Medulla In Cardiovascular Regulation
Authors: Sved Alan F , Ito Satoru , Yajima Yoshiharu
Published: March 2003

1. Excitatory amino acid (EAA)‐mediated neural transmission in the rostral ventrolateral medulla (RVLM) is important for many cardiovascular reflexes, although the receptor subtypes involved vary depending on the specific response.

2. Although injection of the EAA ionotropic receptor antagonist kynurenic acid into the RVLM has no effect on baseline arterial pressure, this lack of effect appears to result from EAA inputs to RVLM exciting both excitatory and inhibitory mechanisms within the RVLM.

3. The balance between EAA‐mediated excitation and inhibition of RVLM neurons may be shifted to excitation in experimental models of hypertension.

4. The excitatory influence that EAA inputs to the RVLM have on vasomotor neurons in the RVLM may involve a sarthran‐sensitive intermediary in the RVLM.
Beneficial Effect Of T‐1095, A Selective Inhibitor Of Renal Na+–Glucose Cotransporters, On Metabolic Index And Insulin Secretion In Spontaneously Diabetic Gk Rats
Authors: Nunoi Kumiko , Yasuda Koichiro , Adachi Tetsuya , Okamoto Yoshimasa , Shihara Nobuyuki , Uno Mika , Tamon Akiko , Suzuki Naoko , Oku Akira , Tsuda Kinsuke
Published: March 2003

1. To investigate the pharmacological effects of T‐1095, this novel derivative of phlorizin was administered to GK rats for 8 weeks. T‐1095 treatment significantly lowered plasma glucose and glycosylated haemoglobin (HbA1c) levels, but did not significantly affect bodyweight.

2. T‐1095 treatment did not affect 3.3 mmol/L glucose‐induced insulin secretion in the isolated perfused pancreas of GK rats.

3. The peak insulin release in T‐1095‐treated GK rats was significantly higher during the first phase than in untreated GK rats (3–4 min after beginning 16.7 mmol/L glucose perfusion). The total amount of insulin secreted during the first phase in T‐1095‐treated GK rats was significantly higher than in untreated GK rats (35.3 ± 1.4 vs 27.3 ± 2.5 ng in T‐1095‐treated compared with untreated rats, respectively).

4. During the second phase, insulin release in T‐1095‐treated GK rats was somewhat higher than in untreated GK rats (7–30 min after beginning 16.7 mmol/L glucose perfusion). The total amount of insulin secreted during the second phase in T‐1095‐treated GK rats was significantly higher than in untreated GK rats (88.2 ± 6.1 vs 68.1 ± 5.7 ng, respectively).

5. The total amount of insulin secreted during perfusion in T‐1095‐treated GK rats was significantly higher than in untreated GK rats (123.5 ± 7.3 vs 95.4 ± 7.7 ng, respectively).

6. These data show that the metabolic indices, plasma glucose and HbA1c levels and insulin secretion are significantly improved by T‐1095 treatment in GK rats, which are spontaneously diabetic rats, suggesting its usefulness as a novel oral therapeutic antidiabetic agent.
Endothelial Function In Mesenteric Resistance Arteries From The Genetically Hypertensive Rat
Authors: Liu Hanzhong , Ledingham Janet M , Mullaney Ian , Laverty Richard
Published: March 2003

1. Endothelial function in mesenteric resistance arteries (MRA) from male 12‐week‐old New Zealand genetically hypertensive (GH) rats and their normotensive control strain (N) was compared in vessels mounted on a wire myograph and by the production of intracellular cGMP. In parallel experiments, MRA from the spontaneously hypertensive (SHR) rat strain, in which there is an endothelial defect, and from GH rats, in which an endothelial defect was induced by chronic nitric oxide synthase (NOS) inhibition with Nω‐nitro‐L‐arginine methyl ester (L‐NAME), were studied.

2. Contractile responses to potassium (124 mmol/L) depolarization and to NA (10–8 to 10–4 mol/L) were similar in GH and N rats; however, in SHR, enhanced contractile responses were found (P < 0.05). The endothelium‐dependent relaxation induced by acetylcholine (ACh; 10–9 to 10–4 mol/L) and endothelium‐ independent relaxation induced by sodium nitroprusside (SNP; 10–9 to 10–4 mol/L) were identical in preparations from GH and N. A significantly attenuated (P < 0.01) vasodilator response to ACh was observed in preparations from SHR.

3. Levels of intracellular cGMP were similar in untreated small mesenteric arterial trees from GH, N and SHR rats. Acetylcholine (10–5 mol/L) significantly (P < 0.001) increased the cGMP content in both GH and N rats. A non‐significant increase occurred in cGMP content in preparations from SHR.

4. In GH rats given L‐NAME (10 mg/kg per day for up to 5 weeks), an attenuated (P < 0.01) endothelium‐dependent relaxation to ACh and an enhanced (P < 0.01) endothelium‐ independent relaxation to SNP were observed. Lower basal cGMP levels were found in preparations from L‐NAME‐treated GH rats and ACh (10–5 mol/L) failed to significantly elevate the cGMP content in these preparations.

5. These experiments failed to show evidence of reduced endothelial function in GH rats, although an endothelial defect in SHR rats and after NOS inhibition in GH rats could be demonstrated.
Smooth Muscle And Endothelial Function Of Arterial Grafts For Coronary Artery Bypass Surgery
Authors: He Guo‐Wei , Yang Qin , Yang Cheng‐Qin
Published: March 2003

1. Various small/mid‐sized conductance arteries have been used for coronary artery bypass grafting as arterial grafts, but unanimous opinion to the best use of these grafts has not been formed.

2. Arterial grafts are not uniform in their biological characteristics.

3. The differences among the arteries may involve the contractility of the vessel. Based on studies of the contractility of arterial grafts, a clinical classification was formed to describe the tendency of vasospasm in the arterial grafts.

4. The differences among arterial grafts also involve endothelial function. This refers to both nitric oxide release from the endothelium, as well as endothelium‐derived hyperpolarizing factor‐mediated hyperpolarization and relaxation.

5. The difference in the peri‐operative behaviour of the grafts and in their long‐term patency may be related to different characteristics. These should be taken into account in the use of arterial grafts, some of which are subject to more active pharmacological intervention during and after operation to obtain satisfactory results. The clinical choice of grafts must be based on the general condition of the patient, the biological characteristics of the graft, the anatomy of the coronary artery, the match between the coronary artery and the graft and the technical considerations, including antispastic management.
Contractile properties of the diaphragm in creatine‐fed rats
Authors: McGuire M , Bradford A , MacDermott M
Published: March 2003

1. Creatine feeding increases the oxidative capacity of type 1 skeletal muscle fibres and, in soleus muscles, consisting mainly of type 1 fibres, increases fatigue resistance. The diaphragm contains a relatively large content of type 1 fibres and respiratory muscle fatigue is a cause of respiratory failure. The aim of the present study was to determine whether creatine supplements increase fatigue resistance in the diaphragm.

2. Rats were given creatine monohydrate (2.55 g/L) in the drinking water. After 5–6 days, isometric contractile properties were measured in strips of costal diaphragm in Krebs' solution at 30°C. Measurements were also made in soleus muscle strips. Values for strips from creatine‐fed rats were compared with those from control rats.

3. Creatine feeding did not increase fatigue resistance and had no effect on twitch or tetanic tension or twitch kinetics in the diaphragm. Creatine increased fatigue resistance in soleus muscles, as reported previously.
Old and new risk factors for atherosclerosis and development of treatment recommendations
Authors: Frohlich Jiri , Lear Scott A
Published: March 2003

1. The development of atherosclerosis, including the role of the classical and new risk factors, is briefly reviewed an emphasis on the links between some of these risk factors and atherogenesis.

2. While genetic factors are doubtlessly important, they contribute (from the population point of view) little to the overall burden of atherosclerosis.

3. Our studies on the relationship between abdominal obesity and metabolic risk factors in two ethnic groups, namely individuals of Cantonese and European background, suggest that different ranges for at least some of the risk factors should be established for specific ethnic groups (e.g. waist circumference for individuals of Chinese and European background).

4. Using the example of differences between Cantonese heterozygotes for familial hypercholesterolaemia living in Vancouver, Canada, and Canton, China, we demonstrate how the environment can modify a genetic predisposition for atherosclerosis.

5. Gender differences are illustrated by a study of serum lipoprotein (a) as a risk factor in men and women.

6. The principles of current Canadian recommendations for the assessment and treatment of atherosclerosis are outlined; they are based on knowledge gained from both basic and clinical research of atherosclerosis.
Is hypertension a leading cause of heart failure in Chinese?
Authors: Nicholls M Gary , Richards A Mark
Published: March 2003

1. There is considerable uncertainty regarding the importance of various risk factors in the development of heart failure. Most data are from Caucasian populations, where hypertension and coronary artery disease appear dominant.

2. Because it cannot be presumed that risk factor profiles will be identical for all races, we reviewed the literature on the aetiology of heart failure in Chinese.

3. There are, apparently, no long‐term prospective studies defining the risk factors for heart failure in Chinese. Studies from Hong Kong in the 1990s point to an overlap of risk factors (especially hypertension, ischaemic heart disease and diabetes) and a high prevalence of diastolic heart failure (66%). Antihypertensive drug treatment appears likely to protect against the development of heart failure but end‐points from formal trials are too small to be certain.

4. Available data, short of being definitive, point to hypertension being the most important identifiable risk factor in Chinese with heart failure. This may change with diabetes mellitus becoming more prevalent in the Chinese population.
Ion channel formation and membrane‐linked pathologies of misfolded hydrophobic proteins: The role of dangerous unchaperoned molecules
Authors: Kourie Joseph I , Henry Christine L
Published: March 2003

1. Protein–membrane interaction includes the interaction of proteins with intrinsic receptors and ion transport pathways and with membrane lipids. Several hypothetical interaction models have been reported for peptide‐induced membrane destabilization, including hydrophobic clustering, electrostatic interaction, electrostatic followed by hydrophobic interaction, wedge × type incorporation and hydrophobic mismatch.

2. The present review focuses on the hypothesis of protein interaction with lipid membranes of those unchaperoned positively charged and misfolded proteins that have hydrophobic regions. We advance the hypothesis that protein misfolding that leads to the exposure of hydrophobic regions of proteins renders them potentially cytotoxic. Such proteins include prion, amyloid β protein (AβP), amylin, calcitonin, serum amyloid and C‐type natriuretic peptides. These proteins have the ability to interact with lipid membranes, thereby inducing membrane damage and cell malfunction.

3. We propose that the most significant mechanism of membrane damage induced by hydrophobic misfolded proteins is mediated via the formation of ion channels. The hydrophobicity based toxicity of several proteins linked to neurodegenerative pathologies is similar to those observed for antibacterial toxins and viral proteins.

4. It is hypothesized that the membrane damage induced by amyloids, antibacterial toxins and viral proteins represents a common mechanism for cell malfunction, which underlies the associated pathologies and cytotoxicity of such proteins.
Spiders of medical importance in the Asia–Pacific: Atracotoxin, latrotoxin and related spider neurotoxins
Authors: Nicholson Graham M , Graudins Andis
Published: March 2003

1. The spiders of medical importance in the Asia–Pacific region include widow (family Theridiidae) and Australian funnel‐web spiders (subfamily Atracinae). In addition, cupboard (family Theridiidae) and Australian mouse spiders (family Actinopodidae) may contain neurotoxins responsible for serious systemic envenomation. Fortunately, there appears to be extensive cross‐reactivity of species‐specific widow spider antivenom within the family Theridiidae. Moreover, Sydney funnel‐web antivenom has been shown to be effective in the treatment of mouse spider envenomation.

2. α‐Latrotoxin (α‐LTx) appears to be the main neurotoxin responsible for the envenomation syndrome known as ‘latrodectism’ following bites from widow spiders. This 120 kDa protein binds to distinct receptors (latrophilin 1 and neurexins) to induce neurotransmitter vesicle exocytosis via both Ca2+‐dependent and ‐independent mechanisms, resulting in vesicle depletion. This appears to involve disruption to a process that normally inhibits vesicle fusion in the absence of Ca2+. Precise elucidation of the mechanism of action of α‐LTx will lead to a major advancement in our understanding of vesicle exocytosis.

3. δ‐Atracotoxins (δ‐ACTX) are responsible for the primate‐specific envenomation syndrome seen following funnel‐web spider envenomation. These peptides induce spontaneous repetitive firing and prolongation of action potentials in excitable cells. This results from a hyperpolarizing shift of the voltage‐dependence of activation and a slowing of voltage‐gated Na+ channel inactivation. This action is due to voltage‐dependent binding to neurotoxin receptor site‐3 on insect and mammalian voltage‐gated Na+ channels in a manner similar, but not identical, to scorpion α‐toxins and sea anemone toxins. δ‐Atracotoxins provide us with highly specific tools to study Na+ channel structure and function

4. ω‐ and Janus‐faced ACTX, from funnel‐web spider venom, are novel neurotoxins that show selective toxicity to insects. In particular ω‐ACTX define a new insecticide target due to a specific action to block insect voltage‐gated Ca2+ channels. Both these ACTX show promise for the development of baculoviral recombinant biopesticides expressing these toxins for the control of insecticide‐resistant agricultural pests. In addition, they should provide valuable tools for the pharmacological and structural characterization of insecticide targets.
Pirfenidone attenuates ischaemia–reperfusion injury in the rat small intestine
Authors: Arumugam Thiruma V , Shiels Ian A , Margolin Solomon B , Taylor Stephen M , Brown Lindsay
Published: March 2003

1. Pirfenidone, an antifibrotic compound with anti‐inflammatory effects, has been investigated in a rat model of acute experimental ischaemia–reperfusion injury of the small intestine.

2. Occlusion of the superior mesenteric artery in young adult female rats for 30 min followed by reperfusion for 120 min induced significant local and systemic effects, including tissue haemorrhage with oedema, elevated serum concentrations of tumour necrosis factor (TNF)‐α, neutropenia, hypotension and bradycardia.

3. Administration of pirfenidone (200 mg/kg, p.o., i.v. or i.p.) 30 min before occlusion completely inhibited the increase in serum TNF‐α concentrations. Pirfenidone inhibited, but did not completely prevent, tissue damage in the small intestine, as well as hypotension and oedema, but neutropenia and bradycardia were not significantly changed by treatment.

4. Thus, pirfenidone effectively moderates both local and some systemic effects of ischaemia–reperfusion injury in the rat small intestine model.
Survival, haemodynamics and cardiac remodelling follow up in mice after myocardial infarction
Authors: Pons S , Fornes P , Hagege AA , Heudes D , Giudicelli J‐F , Richer C
Published: March 2003

1. In the present study, the time‐course, over a 1 year period, of postischaemic dilated cardiomyopathy and/or development of congestive heart failure was investigated in mice in terms of survival and cardiac functional and structural characteristics.

2. C57BL/6 mice with myocardial infarction (MI mice; coronary ligation n = 78) or sham‐operated animals (n = 45) were used and echocardiographic, haemodynamic and histomorphometric parameters were assessed at 3, 6 and 12 months post‐MI.

3. At 12 months, the survival rate was 70% in MI mice. Left ventricular dysfunction was evidenced by a strong decrease in ejection fraction (EF; −48 and −53% at 6 and 12 months, respectively; both P < 0.05) and an increase in left ventricular end‐diastolic pressure (+100% at both 6 and 12 months; both P < 0.05). There was no major worsening in cardiac function between 6 and 12 months, suggesting strong compensatory mechanisms. Cardiac remodelling was observed, characterized by strong left ventricular hypertrophy (+38 and +62% at 6 and 12 months, respectively; both P < 0.05) and dilatation (+53% at 6 months; P < 0.05), but collagen was not significantly increased. Significant correlations were found between EF (echocardiography) and dP/dtmax, between end‐diastolic volume (echocardiography) and left ventricular internal perimeter (histomorphometry) and between left ventricular mass (echocardiography) and weight.

4. In conclusion, despite a high survival rate, the MI mouse model displays most of the hallmarks of postischaemic dilated cardiomyopathy and/or congestive heart failure, thus affording the necessary background for the subsequent evaluation of gene manipulation and/or drug effects. In addition, two‐dimensional echocardiography appears to be a suitable tool for the long‐term follow up of cardiac function and remodelling in this model.
RNA interference may be more potent than antisense RNA in human cancer cell lines
Authors: Aoki Y , Cioca DP , Oidaira H , Kamiya J , Kiyosawa K
Published: March 2003

1. RNA interference (RNAi) is a newly discovered cellular pathway for the silencing of sequence‐specific genes at the mRNA level by the introduction of the cognate double‐stranded (ds) RNA . Because antisense (AS) mechanisms have similar effects, we compared these two effects in human cancer cell lines, considering a possible application of RNAi for cancer therapy.

2. We tested RNAi effects by transfecting human hepatoma and pancreatic cancer cell lines with AS and sense (S) RNA expression plasmids corresponding to the exogenous luciferase gene or the endogenous c‐raf gene in the form of complexes with a cationic lipopolyamine or a tumour‐targeting peptide vector we developed. In addition, we compared the effects of small interfering RNA and AS oligoDNA complexed with the peptide vector.

3. From the viewpoint of AS actions, the effect of the AS RNA may be cancelled by the S RNA, although, interestingly, we found that the combination of the AS and S RNA expression plasmids was more effective than the AS RNA expression plasmids alone in reducing target gene expression, whereas the S RNA expression plasmids had no effects. The combination of the luciferase AS and S RNA had no effects on the expression of either the β‐galactosidase gene or the c‐raf gene. In the presence of 2‐aminopurine (an inhibitor of dsRNA‐activated protein kinase), the inhibitory effect of the combination of AS and S RNA on gene expression did not change in the case of the endogenous c‐raf gene, but was reduced in the case of the exogenous luciferase gene. The effect of 22 nucleotide RNA duplexes corresponding to the luciferase gene was by one order stronger than that of the phosphorothioate AS DNA.

4. Thus, it is suggested that RNAi may be more potent than AS RNA in reducing target gene expression in human cancer cell lines, regardless of the length of dsRNA. With further studies on the RNAi phenomenon in cancer cells, RNAi could provide a novel approach for cancer gene therapy.
Disposition kinetics of ketotifen from liposomal dry powder for inhalation in rat lung
Authors: Joshi Mayank , Misra Ambikanandan
Published: March 2003

1. The aim of the present study was to understand the benefit of liposomal dry powder for inhalation (LDPI) of ketotifen fumarate (KF) over plain drug dry powder for inhalation as a pulmonary targetted drug‐delivery system.

2. The KF liposomes, composed of egg phosphatidyl choline and cholesterol, were prepared by the lipid film hydration technique. The liposomal dispersion was freeze dried and formulated to a dry powder for inhalation. Values of 89.0–65.3% drug entrapment of freeze‐dried liposomes were estimated in prepared batches.

3. Rehydrated KF liposomes formed by the hydration of LDPI or the plain KF solution was delivered to rat lungs by intratracheal instillation. Simultaneous monitoring of drug levels in the bronchoalveolar lavage and lung tissue enabled assessment of pulmonary drug disposition.

4. Cumulative drug levels in lung tissue after intratracheal administration revealed that with liposomes targetting factors were between 1.36 and 1.54. The maximal drug concentration in lung homogenate for LDPI was 42.0 µg compared with 73.6 µg for plain drug solution.

5. Similarly, the time to reach maximum drug concentration in the lung homogenate for liposomal dry powder was 9–12 h compared with 3 h for plain drug.

6. Hence, the use of LDPI of KF was found to provide desired drug levels in the lung for a long time and thereby increased pulmonary targetting

7. This is expected to enhance the therapeutic index of the drug and probably reduce the dose administered and the cost of therapy.
Involvement of Wnt‐5a in chondrogenic pattern formation in the chick limb bud
Authors: Kawakami Yasuhiko , Wada Naoyuki , Nishimatsu Shin‐ichiro , Ishikawa Tetsuya , Noji Sumihare , Nohno Tsutomu
Published: March 2003

Members of the Wnt family are known to play diverse roles in the organogenesis of vertebrates. The full‐coding sequences of chicken Wnt‐5a were identified and the role it plays in limb development was examined by comparing its expression pattern with that of two other Wnt members, Wnt‐4 and Wnt‐11, and by misexpressing it with a retrovirus vector in the limb bud. Wnt‐5a expression is detected in the limb‐forming region at stage 14, and in the apical ectodermal ridge and distal mesenchyme of the limb bud. The signal was graded along the proximal–distal axis at stages 20–28 and also along the anterior–posterior axis during early stages. It disappeared in the cartilage‐forming region after stage 26, and was restricted to the region surrounding the phalanges at stage 34. Wnt‐4 and Wnt‐11, other members of the Wnt‐5a‐subclass, were expressed with a distinct spatiotemporal pattern during the later phase. Wnt‐4 was expressed in the articular structure and Wnt‐11 was expressed in the dorsal and ventral mesenchyme adjacent to the ectoderm. Wnt‐5a expression was partially reduced after apical ectodermal ridge removal, whereas Wnt‐11 expression was down‐regulated by dorsal ectoderm removal. Therefore, expression of these Wnt was differentially regulated by the ectodermal signal. Misexpression of Wnt‐5a in the limb bud with the retrovirus resulted in truncation of long bones predominantly in the zeugopod because of retarded chondrogenic differentiation. Distal elements, such as the phalanges and metacarpals, were not significantly reduced in size. These results suggest that Wnt‐5a is involved in pattern formation along the proximal–distal axis by regulation of chondrogenic differentiation.