bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cardiac hypertrophy: A matter of translation
Authors: Hannan RD , Jenkins A , Jenkins AK , Brandenburger Y 
Published: July 2003

Summary1. Left ventricular hypertrophy (LVH) of the heart is an adaptive response to sustained increases in blood pressure and hormone imbalances. Left ventricular hypertrophy is associated with programmed responses at the molecular and biochemical level in different subsets of cardiac cells, including the cardiac muscle cells (cardiomyocytes), fibroblasts, conductive tissue and coronary vasculature.2. Regardless of the initiating cause, the actual increase in chamber enlargement is, in each case, due to an increase in size of a pre‐existing cardiomyocyte population, with little or no change in their number; a process referred to as cellular hypertrophy.3. An accelerated rate of global protein synthesis is the primary mechanism by which protein accumulation increases during cardiomyocyte hypertrophy. In turn, increased rates of synthesis are a result of increased translational rates of existing ribosomes (translational efficiency) and/or synthesis and recruitment of additional ribosomes (translational capacity).4. The present review examines the relative importance of translational capacity and translational efficiency in the response of myocytes to acute and chronic demands for increased protein synthesis and the role of these mechanisms in the development of LVH.
Effects of chronic hypobaric hypoxia on contractile properties of rat sternohyoid and diaphragm muscles
Authors: El‐Khoury R , O'Halloran KD , Bradford A 
Published: July 2003

Summary1. Chronic hypoxia occurs in a variety of circumstances, including respiratory disease and exposure to altitude, and is known to affect respiratory muscle structure. However, little is known about its effects on respiratory muscle contractile properties.2. Rats were exposed to normoxia (n = 16) or hypobaric hypoxia (n = 16; barometric pressure 450 mmHg) for 6 weeks. Contractile properties were measured in isolated sternohyoid and diaphragm muscles in warmed, oxygenated Krebs' solution. Isometric twitch and tetanic tension, contraction time, half‐relaxation time and tension–frequency relationship were determined using field stimulation with platinum electrodes. Fatigue was induced by stimulation at 40 Hz with 300 msec trains of 0.5 Hz for 5 min.3. Chronic hypoxia had no effect on bodyweight, but did increase haematocrit. Chronic hypoxia increased specific force development in both muscles and increased sternohyoid fatigue. Chronic hypoxia had no effect on contractile kinetics in either muscle, but shifted the tension–frequency relationship to the left in the diaphragm.4. Therefore, chronic hypoxia alters rat respiratory muscle force and fatigue, either due to the direct effects of hypoxia or to increased muscle activation.
Effect of nitroglycerine in popliteal preparations from patients with peripheral occlusive arteriopathy precontracted with KCl or 5‐hydroxytryptamine
Authors: Ortega Ana , Avellanal Martin , España Gabriel , Flores Angel , Aleixandre Amaya 
Published: July 2003

Summary1. At the present time, there are no studies in isolated arteries from patients suffering from peripheral occlusive arteriopathy (POA). In the present study, we attempt to characterize the effect of nitroglycerine (GTN) in isolated popliteal preparations obtained after leg amputation in 60–90‐year‐old men and women suffering from POA.2. After surgical operation, arterial samples were stored in a refrigerator at 4°C and, after 12–36 h, they were cut into rings and mounted in organ baths containing Krebs'–Henseleit solution at 37°C and gassed constantly with 95% CO2 and 5% O2. Because noradrenaline elicited very poor contractile responses in these preparations, in the present study we evaluated the concentration‐dependent contractions induced by KCl (15–90 mmol/L) and 5‐hydroxytryptamine (5‐HT; 10−7 to 10−4 mol/L) in arteriopathic popliteal rings and, when the corresponding maximum contractile effect had been obtained, we also evaluated the concentration‐dependent relaxing effect produced by GTN (10−10 to 10−5 mol/L) in all precontracted preparations. As a reference, similar experiments were performed in popliteal preparations obtained following surgery on non‐arteriopathic vascular tissue where it was necessary to resect a certain percentage of healthy vessel.3. The responses to KCl and 5‐HT were greater in healthy vessel than in arteriopathic rings. The relaxing effect of GTN was greater in preparations precontracted with 5‐HT than in those preparations precontracted with KCl. In addition, preparations precontracted with KCl relaxed even less when they were obtained from patients with POA.4. The present data indicate that GTN is a vasodilator with little effect on depolarized arteries. The results also indicate that the effect of this drug is even less in depolarized arteries from patients with POA.
ON BEING THE RIGHT SIZE: HEART DESIGN, MITOCHONDRIAL EFFICIENCY and LIFESPAN POTENTIAL
Authors: Dobson Geoffrey P 
Published: July 2003

Summary1. From the smallest shrew or bumble‐bee bat to the largest blue whale, heart size varies by over seven orders of magnitude (from 12 mg to 600 kg). This study reviews the scaling relationships between heart design, cellular bioenergetics and mitochondrial efficiencies in mammals of different body sizes.2. The [31P]‐nuclear magnetic resonance‐derived [phosphocreatine]/[ATP] ratio in hearts of smaller mammals is significantly higher (2.7 ± 0.3 for mouse;n = 22) than in larger mammals (1.6 ± 0.3 for humans;n = 13).3. The inverse of the free myocardial cytosolic [ADP] concentration and the cytosolic phosphorylation ratio ([ATP]/[ADP][Pi]) scales with heart size and with absolute mitochondrial and myofibrillar volumes, close to a quarter‐power (from −0.22 to −0.28;r = 0.99).4. Assuming a similar mitochondrial P/O ratio and the same maximal amount of work required to convert 1 mol NADH to 0.5 mol O2(i.e. 212.25 kJ/mol), the higher [ATP]/[ADP][Pi] ratios or cellular driving forces (ΔG′ATP) in hearts of smaller mammals imply greater mitochondrial efficiencies in coupling ATP production to electron transport as body size decreases. For a P/O ratio of 2.5, the mitochondrial efficiency in the heart of a shrew, mouse, human and whale is 84, 82, 71 and 65%, respectively.5. Higher cytosolic ATP]/[ADP][Pi] ratios and ΔG′ATPvalues imply that the hearts of smaller mammals operate further from equilibrium than hearts of larger mammals.6. As a consequence of scaling relationships, a number of remarkable invariants emerge when comparing heart function from the smallest shrew to the largest whale; the total volume of blood pumped by each heart in a lifetime is approximately 200 million L/kg heart and the total number of heart beats is approximately 1.1 billion per lifetime.7. Similarly, the metabolic potential (total O2consumed during adult lifespan per g bodyweight) for a 2 g shrew or a 100 000 kg blue whale is approximately 38 L O2consumed or 8.5 mol ATP/g body mass per lifetime.8. The importance of quarter‐power scaling relationships linking structural, metabolic and bioenergetic design to the natural ageing process and maximum lifespan potential is discussed.
SPECIES‐INDEPENDENT METABOLIC RESPONSE TO AN INCREASE OF [Ca2+]i IN QUIESCENT CARDIAC MUSCLE
Authors: Ward Marie‐Louise , Cooper Patricia J , Hanley Peter J , Loiselle Denis S 
Published: July 2003

Summary1. The aim of the present investigation was to contrast the Ca2+ dependence of cardiac energy metabolism in two species with differential reliance on extracellular Ca2+ for excitation–contraction coupling.2. We measured energy expenditure as the rate of oxygen consumption (V̇o2) of isolated, Langendorff‐perfused hearts of rats and guinea‐pigs during KCl arrest. In parallel experiments, we indexed intracellular Ca2+ concentration ([Ca2+]i) of isolated right‐ventricular trabeculae, using the Ca2+ fluorophore fura‐2 and ratiometric spectrofluorometry. By varying extracellular Na+ concentration ([Na+]o), V̇o2–[Na+]o and [Ca2+]i–[Na+]o relationships were constructed for each species.3. Reduction of [Na+]o during K+ arrest caused pronounced species‐dependent elevations of both V̇o2 and [Ca2+]i. Despite the species dependence of both V̇o2 and [Ca2+]i on [Na+]o, a single species‐independent V̇o2–[Ca2+]i relationship obtained.4. We infer that elevation of the metabolic rate of the arrested heart above its basal value is determined primarily by [Ca2+]i and is not species dependent.
Cardiac energetics: Sense and nonsense
Authors: Gibbs Colin L 
Published: July 2003

Summary1. The background to current ideas in cardiac energetics is outlined and, in the genomic era, the need is stressed for detailed knowledge of mouse heart mechanics and energetics.2. The mouse heart is clearly different to the rat in terms of its excitation–contraction (EC) coupling and the common assumption that heart rate difference between mice and humans will account for the eightfold difference in myocardial oxygen consumption is wrong, because the energy per beat of the mouse heart is approximately one‐third that of the human heart.3. In vivo evidence suggests that there may well be an eightfold species difference in the non‐beating metabolism of mice and human hearts. It is speculated that the magnitude of basal metabolism in the heart is regulatable and that, in the absence of perfusion, it falls to approximately one‐quarter of its in vivo rate and that in clinical conditions, such as hibernation, it probably decreases; its magnitude may be controlled by the endothelium.4. The active energy balance sheet is briefly discussed and it is suggested that the activation heat accounts for 20–25% of the active energy per beat and cross‐bridge turnover accounts for the balance. It is argued that force, not shortening, is the major determinant of cardiac energy usage.5. The outcome of recent cardiac modelling with variants of the Huxley and Hill/Eisenberg models is described. It has been necessary to invoke ‘loose coupling’ to replicate the low cardiac energy flux measured at low afterloads (medium to high velocities of shortening).6. Lastly, some of the unexplained or ‘nonsense’ energetic data are outlined and eight unsolved problems in cardiac energetics are discussed.
CARDIAC ENERGETICS: FROM EMAX TO PRESSURE–VOLUME AREA
Authors: Suga Hiroyuki 
Published: July 2003

Summary1. To celebrate this Festschrift for Professor Colin Gibbs, as an invited speaker, I would like to review briefly my 35 year research career in cardiac physiology.2. My career started in the late 1960s in Tokyo with my serendipitous discovery of Emax (ventricular end‐systolic maximum elastance) as a load‐independent contractility index based on the time‐varying elastance (E(t)) model of the ventricle. Professor K Sagawa at the Johns Hopkins University, USA, whom I joined in 1971, encouraged me to go further.3. The next serendipitous event in my career was the discovery of ventricular pressure–volume area (PVA) as a measure of total mechanical energy of ventricular contraction in the late 1970s. The PVA concept was theoretically deducible from the E(t) and Emax concept and correlated surprisingly well with ventricular O2 consumption (Vo2).4. Professor Gibbs' intuitive recognition of the significance of PVA in myocardial energetics in the 1980–1990s greatly encouraged me thereafter. The third serendipitous event in my career occurred in the mid 1990s and was my discovery of a novel integrative analysis method to assess the total amount of Ca2+ recruited in each excitation–contraction coupling from the decay rate of postextrasystolic potentiation, taking advantage of the Emax–PVA–Vo2 framework.5. I am now hoping to experience one more serendipitous experience by developing an integrative analysis method of cross‐bridge cycling in a beating heart using the Emax and PVA concepts.
Force‐matching errors after eccentric exercise attributed to muscle soreness
Authors: Proske U , Weerakkody NS , Percival P , Morgan DL , Gregory JE , Canny BJ 
Published: July 2003

Summary1. Experiments were performed to test the ability of human subjects to match forces in their elbow flexor muscles following eccentric exercise of one arm and, in a second series, after biceps brachii of one arm had been made sore by injection of hypertonic saline.2. In the force‐matching task, the elbow flexors of one arm, the reference arm, generated 30% of maximum voluntary contraction (MVC) under visual control. Subjects matched that level with their other arm, the indicator arm, without visual feedback.3. After eccentric exercise of elbow flexors of the indicator arm, subjects felt they had achieved a satisfactory match while indicating forces that were significantly lower, by approximately 5%, than the reference level. Errors were in the opposite direction (i.e. forces were overestimated) when the reference arm was exercised.4. Errors were reduced when matching forces were expressed as fractions of the sessional MVC rather than the pre‐exercise MVC. Residual errors from 24 h postexercise onwards were attributed to muscle soreness from the exercise.5. In support of this view, a similar pattern of matching errors was observed when an unexercised arm was made sore by injection of hypertonic saline into the biceps.6. It is concluded that muscle soreness can interfere with a subject's ability to match forces, perhaps as a result of a reduced excitability of motor cortex. It implies that muscle soreness may contribute to the weakness experienced after a period of unaccustomed eccentric exercise.
Relationship between isometric force and myofibrillar MgATPase at short sarcomere length in skeletal and cardiac muscle and its relevance to the concept of activation heat
Authors: Stephenson D George 
Published: July 2003

Summary1. This paper has been written in recognition of the seminal contributions to cardiac and skeletal muscle energetics made by Professor Colin Gibbs during his distinguished academic career.2. The paper focuses on what is now known about the relationship between Ca2+‐activated isometric force production and myofibrillar MgATPase in intact and skinned (surface membrane rendered permeable) skeletal and cardiac muscle preparations at short sarcomere lengths.3. The relevance of this relationship to understanding the interactions between the actin and myosin filaments at the cross‐bridge level in the region of double actin filament overlap and the cellular basis of ‘activation heat’ measurements in intact striated muscles is discussed.
Energy cost of contraction in rat urinary bladder smooth muscle during anoxia
Authors: Wendt Igor R , Paul Richard J 
Published: July 2003

Summary1. The aim of the present study was to investigate the effects of hypoxia on energy metabolism and contraction of rat urinary bladder smooth muscle, thereby gaining insight into the capacity of this smooth muscle to maintain contractile function when rendered hypoxic.2. Isometric force, oxygen consumption, lactate production, heat production and unloaded shortening velocity were measured in isolated muscle strips under both aerobic and anaerobic conditions. Muscle strips were bathed in physiological saline solution with the anaerobic condition being created by replacing the oxygen bubbling the solution with nitrogen.3. During contraction under anaerobic conditions, the rate of lactate production was increased 2.5‐fold above that observed under aerobic conditions. This, however, only provided for a rate of ATP production of approximately 30% of that measured under aerobic conditions. Despite this, force maintenance was only slightly depressed, indicating that the metabolic cost of contraction was reduced in hypoxia. In support of this, the rate of heat production during contractions in anoxia was only approximately half of that under aerobic conditions, whereas, again, force was only slightly lower. Unloaded shortening velocity was significantly lower in anoxia, suggesting a slower cross‐bridge turnover rate.4. The results indicate that the economy of force maintenance is increased in bladder smooth muscle under hypoxic conditions and that this is due, at least in part, to a reduced rate of cross‐bridge cycling. This may help to preserve bladder contractile function during periods of ischaemia that may be associated with bladder filling and emptying.
Membranes as metabolic pacemakers
Authors: Else Paul L , Hulbert Anthony J 
Published: July 2003

Summary1. In the present review, we suggest that a few common processes linked to membranes consume the majority of energy used by most organisms.2. Membranes may act as metabolic pacemakers through changes in lipid composition, altering membrane characteristics and the working environment of membrane proteins.3. Experiments involving membrane exchanges show predictable changes in protein activities (sodium pump) that are dependent upon the type of membrane used.4. Potential mechanisms discussed include fluidity, electrical fields, surface area requirements of lipids and peptide–lipid interactions.
The accuracy of external blood loss estimation by ambulance and hospital personnel
Authors: Tall Gary , Wise David , Grove Peter , Wilkinson Chris 
Published: July 2003

AbstractObjective: To determine if emergency personnel, either ambulance or hospital based, can estimate the volume of external blood loss accurately enough to be of potential clinical use in guiding fluid resuscitation.Methods: A total of 61 ambulance and 35 hospital personnel viewed nine scenarios consisting of volumes of blood (100 mL, 400 mL and 700 mL) spilt onto three surfaces — carpet, vinyl and a clothed manikin. They were asked to estimate the blood loss in each case.Results: Estimates of volumes of blood loss on all surfaces were generally inaccurate. Both ambulance and hospital groups were comparable in this regard. Hospital personnel had higher mean estimates than those of ambulance personnel. Of particular clinical relevance were the findings that blood loss on carpet was underestimated and small volumes on a clothed manikin were overestimated.Conclusion: External blood loss estimation by ambulance and hospital personnel is generally too inaccurate to be of clinical use.
The heaviest repeat users of an inner city emergency department are not general practice patients
Authors: Dent Andrew Wesley , Phillips Georgina A , Chenhall Antony J , McGregor Lachlan Robert 
Published: July 2003

AbstractObjective: To test the hypothesis that frequent attenders to the ED are suitable for diversion to general practice.Methods: A retrospective review of a computerized database for the top 500 frequent presenters to an inner city adult teaching hospital ED.Results: Five hundred patients presented 12 940 times, an average of 26 times per patient, accounting for (8.4%[8.3, 8.6]) of total ED presentations over 64 months. There were 7699 (59.5%[58.7, 60.4]) presentations deemed appropriate for ED. Of the remaining 5241 presentations, 1553 (29.6%[28.4, 30.9]) were between 22.00 and 07.00 hours, outside the hours of most actual or proposed primary care clinics. This left 3688 (28.5%[27.7, 29.3]) presentations by the heaviest users of the ED as potentially appropriate for general practice. Of these presentations 1507 (40.9%[39.3, 42.5]) were by people who were homeless. A total of 2574 (69.8%[68.3, 71.3]) had pre‐existing case management, either by the hospital or another service. Nine hundred and seventy‐eight (26.5%[25.1, 28.0]) had primary psychiatric or altered conscious states due to drugs and alcohol as the presenting problem. At least 90 of these 500 frequently presenting patients died during the study period.Conclusion: The majority of the presentations by the heaviest users of an ED in a city teaching hospital are not suitable for general practice. Attempting diversion of the heaviest repeat ED users to a general practice in this setting may not be successful due to the severity, acuity and nature of casemix of the presentations and would have minimal impact on crowding in similar emergency departments.
Inpatient mortality as related to triage category in three New South Wales regional base hospitals
Authors: Doherty Steven R , Hore Craig T , Curran Shane W 
Published: July 2003

AbstractObjective: To establish the incidence of death after admission via the ED for each of the five categories of the Australasian Triage Scale in three New South Wales base hospitals, and to compare this with published data from an adult tertiary referral hospital in Victoria. To examine the causes of death in each category.Methods: Information was collected from databases established as part of quality assurance projects at three New South Wales rural base hospitals from 1 January 2000 to 31 December 2000.Results: Overall mortality rates per ED presentation and per ED admission were significantly lower than for similar data from an adult tertiary referral hospital. There were significant differences in mortality per ED presentation for categories 2, 3 and 4 and significant differences in mortality per admission for Australasian Triage Scale categories 2 and 3. The commonest causes of death were acute cardiac/respiratory and malignancy related conditions. Triage category 3 had both the highest number of total admissions and the highest number of deaths post admission. This finding differs from published data from an adult tertiary referral hospital where category 4 represented the largest number of admissions and of in‐hospital deaths following admission.Conclusion: This study has established the mortality rates per ED presentation and admission for each of the five categories of the Australasian Triage Scale in three New South Wales rural base hospitals. Significant differences were found between these rates and the published rates for an adult tertiary referral hospital.
Spectrum of acute allergic diseases in an emergency department: An evaluation of one years’ experience
Authors: Bellou Abdelouahab , Manel Jacques , Samman‐Kaakaji Hassan , De Korwin Jean Dominique , Moneret‐Vautrin Denise Anne , Bollaert Pierre‐Edouard , Lambert Henri 
Published: July 2003

AbstractObjective: There is limited available literature on the incidence of allergic diseases in ED. The objective of this study was to investigate the clinical records of patients admitted to the ED with a suspected allergic reaction.Methods: A 1 year retrospective study was carried out and data were collected from the patients’ computerized medical reports.Results: A total of 324 patients were admitted for an allergic event. Of those, 165 patients (50.9%) were female and their mean age was 55 ± 18.5 years. Diagnoses included: asthma in 100 patients (30.9%); hymenoptera allergy in 78 patients (24.1%); food allergy in 31 patients (9.5%); drug allergy in 25 patients (7.7%); and allergic conjunctivitis in 12 patients (3.7%). No diagnosis was found in the medical records of 78 patients (24.1%). Anaphylactic shock was observed in 12 patients (3.7%) with a diagnosis of food allergy (six cases), drug allergy (three cases) and hymenoptera allergy (three cases). Ninety patients (27.7%) were hospitalized in the following units: 38 in allergy unit (42.2%); 20 in intensive care unit (22.2%); 10 in pulmonary unit (11.1%); eight in the dermatology unit (8.9%); six in the internal medicine unit (6.7%); and eight in other units (8.9%). Overall, 42 patients (12.9%) were evaluated by an allergologist after ED discharge with positive allergy results in 28 cases (66.6%).Conclusions: Acute allergic diseases are not rare in ED, representing 1% of the annual visits in our series. A low rate of allergologist referral was observed. Emergency physicians must work closely with allergologists to ensure a better evaluation, long‐term care and preventive management of patients with allergic diseases admitted to the ED.