bluuebunny/crossref_metadata_2025 huggingface dataset:
The gut as a potential trigger of exercise-induced inflammatory responses
Authors: Marshall John C
Published: April 2011

Multiple lines of evidence support the hypothesis that ischemia-induced impairment of normal gut barrier function, with loss of the normal tonic counterinflammatory influence of the gut immune system, contributes to the expression of uncontrolled inflammation in critically ill victims of trauma and overwhelming infection. The clinical syndrome known as the systemic inflammatory response syndrome (SIRS), which embodies uncontrolled inflammation in trauma and sepsis, is reproduced in its entirety by vigourous exercise, raising the possibility that the gut may also play a role in exercise-induced inflammation. Both strenuous exercise and systemic sepsis result in impairment of the normal gut barrier to luminal microorganisms, and result in elevated circulating levels of bacterial endotoxin. Under normal circumstances, the immune tissues of the gut-liver axis inhibit the expression of a host response to foodstuffs in the gut lumen, or to the indigenous microbial flora of the gut wall. This influence is an active, energy-requiring process. Both strenuous exercise and critical illness are associated with gut ischemia, providing a common biologic basis for the initiation of a dysregulated inflammatory response. Although direct evidence supporting or refuting the hypothesis that the gut can serve as a trigger for systemic inflammation following strenuous exercise is sparse, the similarities in the clinical manifestations of SIRS and exercise, and the promising results of prophylactic or therapeutic gut-directed strategies in critical illness, suggest that similar approaches may provide benefit for individuals engaged in extreme physical exercise.Key words: sepsis, exercise, endotoxin, gastrointestinal immunity, inflammation.
Cellular responses to moderate and heavy exercise
Authors: Nehlsen-Cannarella Sandra L
Published: April 2011

Moderate and heavy exercise induce a multitude of changes in the neuroendocrine immune system, the net effects of which depend on various other factors including the host's physical condition, and the intensity and duration of the exercise bout. Most investigators report that the risk of upper respiratory infection is increased following heavy exertion, but is decreased after moderate exercise. Many heavy exercise-induced changes in the host's immune defenses are consistent with the alterations reported in classical stress studies; some consensus has been achieved in this area that heavy exertion may indeed elicit responses common to psychological forms of stress. The immunomodulation consists, most notably, of shifts in the number and function of circulating innate and adaptive immune cell populations apparently in response to the release of classical stress hormones and cytokines, and expression of selectin and adhesin molecules. Rapid trafficking of cells in and out of the blood compartment in response to exertion probably mirrors the demand for certain cell types in specific tissues, a hypothesis requiring verification in animal models and ultimately the human. Also needed are studies correlating the functional status of the circulating cells with those in the tissues.Key words: neuroendocrine immune system, exercise-induced stress, upper respiratory tract infections, immunomodulation, immune defenses.
Exercise and resistance to infection
Authors: Nieman David C
Published: April 2011

Epidemiological data suggest that endurance athletes are at increased risk for upper respiratory tract infection (URTI) during periods of heavy training and the 1- to 2-week period following race events. Moderate exercise training has been associated with a reduction in incidence of URTI. There is growing evidence that for several hours subsequent to heavy exertion, several components of both the innate (e.g., natural killer cell activity and neutrophil oxidative burst activity) and adaptive (e.g., T and B cell function) immune system exhibit suppressed function. The immune response to heavy exertion is transient, and further research on the mechanisms underlying the immune response to prolonged and intensive endurance exercise is necessary before meaningful clinical applications can be drawn. Some attempts have been made through chemical or nutritional means (e.g., indomethacin, glutamine, vitamin C, and carbohydrate supplementation) to attenuate immune changes following intensive exercise to lower the risk of infection.Key words: upper respiratory tract infection, immunity, running, lymphocyte, neutrophil.
Novel attributes of an androgenic steroid-mediated increase in cardiac end diastolic stiffness in rats
Authors: Trifunovic Boris , Woodiwiss Angela J , Duffield Marc , Norton Gavin R
Published: April 2011

Although cardiac early and mid-diastolic stiffness constants are well accepted as being modulated by alterations in myocyte active processes, increments in left ventricular end diastolic (LVED) stiffness (LVED k; g·cm-2) in classical pathological models of a reduced LVED k (e.g., diabetes mellitus (DM) and hypertension) are determined largely by the properties of the myocardial extracellular matrix (ECM). As such, increases in LVED k in the latter cardiac pathologies are insensitive to acute changes in cardiac load, heart rate, and contractility. We examined whether the same attributes that apply to changes in LVED k in DM and in spontaneously hypertensive rats (SHRs) also apply to an androgenic steroid (nandrolone decanoate; 5 mg·kg-1 biweekly) induced increase in LVED k. Myocardial collagen (ECM) characteristics and the capacity of acute verapamil-mediated changes in cardiac dynamics to impact on LVED k were evaluated after 3 months of steroid treatment to rats, 4 months of DM in rats, and in 45-week-old SHRs. Chronic steroid administration increased LVED k (steroid = 42 ± 4, control = 25 ± 2; p < 0.01). An acute infusion of verapamil to steroid-treated rats decreased LVED k to values not different from controls (29 ± 3; p < 0.05 as compared with LVED k at baseline). Measures of myocardial collagen concentrations, phenotype ratios, and cross-linking were unchanged following steroid administration. Verapamil failed to alter the increased LVED k that occurs in either rats with DM or in SHRs, despite similar effects on cardiac dynamics as those noted in steroid-treated rats. The increased LVED k in the former animal models was associated with alterations in the ECM. In conclusion, the unique lack of association of the androgenic steroid-induced increase in LVED k with alterations in the myocardial ECM and the novel sensitivity of the steroid-mediated increment in LVED k to acute alterations in cardiac dynamics further supports the notion that changes in LVED k should not be considered to be a reflection of ECM characteristics in all cardiac conditions.Key words: anabolic steroids, diastole, collagen.
Adhesion molecules during immune response to exercise
Authors: Gabriel Holger HW , Kindermann Wilfried
Published: April 2011

Cell-cell and cell-matrix contacts are dependent on cell surface density, localization, and avidity state of adhesion molecules. These adhesion molecules are involved in all steps of the leukocyte's adhesion process. Selectins, molecules of the immunoglobulin superfamily, and integrins are necessary for an initial tethering, triggering, firm attachment, and transendothelial migration of leukocytes. Hormones, cytokines, other pro-inflammatory agents, and shedded receptors like the LPS-receptor significantly alter the adhesion process. Infectious and noninfectious inflammatory processes are capable of inducing an altered adhesion of leukocytes to endothelial cells. The result is a preferential homing of leukocytes to sites of inflammation. Acute bouts of exercise may induce a release or secretion of many of the aforementioned substances involved in the adhesion process. The acute immune response to exercise is strongly influenced by the activation of the sympathetic nervous system and the hypothalamo-pituitary-adrenal axis. During the first 10-30 min of exercise an almost maximal increase of T and B lymphocytes, monocytes, and NK cells from the marginal pool into the blood circulation is induced. This demargination of cells is likely an effect mediated by beta2 adrenergic receptors and probably due to a change of the avidity state of adhesion molecules. Strenuous exercise is associated with an increase of serum cortisol resulting in a delayed neutrocytosis and lymphocytopenia. Both phenomena are due to altered circulation patterns. It will be discussed how far adhesion molecules might contribute to this effect. Furthermore an evaluation of contradicting experimental results about surface expression of selectins and integrins will be provided.Key words: CD11a/CD18, CD11b/CD18, LFA-1, inflammation, infections, exercise, monocytes, neutrophils, lymphocytes.
Conduction block in Purkinje fibers by homogeneous versus localized decrease of the gap junction conductance
Authors: Daleau Pascal , Délèze Jean
Published: April 2011

Gap junction channels provide the pathway for the cell-to-cell propagation of cardiac action potential.Impairment of junctional conductance decreases conduction velocity and can cause block, two conditions that favorventricular arrhythmias and fibrillation by re-entrant excitation. These experiments were designed to examine theeffects of homogeneous versus localized decrease of the gap junction conductance on propagation of action potential inPurkinje fibers from sheep hearts. The fibers were mounted in a three-compartment chamber, and cell-to-cellconductance was progressively reduced by applying heptanol either over a central 2-mm segment or over the wholefiber length. The internal resistivities (Ri ) at which conduction of the action potential became blocked were determinedin both cases. With 3.5 mM heptanol in the central compartment, conduction failed when Ri was increased by only34.6 times the control values. In contrast, when the same concentration of heptanol was added simultaneously to allthree compartments, Ri had to rise by a factor of 7.59.4 before conduction became decremental and was blocked. Inboth situations, dV/dtmax at the time of conduction block was similarly decreased to about 50% of the control values.Other parameters being equal, a moderate decrease of the gap junction conductance and of the fast sodium current,insufficient to block propagation of the action potential when they are homogeneously distributed, become sufficient tointerrupt conduction if the action potential merges abruptly into a portion of fiber with normal internal conductivity atthe outlet of the area of increased resistance. This greater sensitivity to block is accounted for by the increase inelectrical load at the discontinuity in the core conductor between the region of increased internal resistance and thenormal part of fiber that follows. Areas of steep transition from high to low input resistances of the core conductor,such as may develop in localized ischemia, therefore appear particularly susceptible to conduction failure.Key words: electrical uncoupling, internal resistivity measurement, discontinuous internal resistance, arrhythmia, sheep heart.
Positive inotropy due to lowering cyclic GMP is also mediated by increases in cyclic AMP in control and hypertrophic hearts
Authors: Naim Karen L , Rabindranauth Prem , Weiss Harvey R , Tse James , Leone, Jr. Richard J , Scholz Peter M
Published: April 2011

The aim of the current study was to determine if lowering myocardial cyclic GMP by guanylate cyclase inhibition would add independently to the positive inotropic effects caused by raising cyclic AMP and if these effects are modified in left ventricular hypertrophy (LVH) produced by aortic valve plication. Isoproterenol (ISO) (0.1 mg·kg-1·min-1) was infused into a branch of the left anterior descending coronary artery of seven control and eight hypertrophy open-chest anesthetized dogs. After 10 min, simultaneous infusion of methylene blue (MB) (2 mg·kg-1·min-1) was initiated at the same site. Hypertrophy increased heart weight and heart weight / body weight ratio. While both drugs increased left ventricular dP/dtmax, no additional global effects were observed in either group. Changes in regional variables followed the same pattern in both groups, i.e., ISO produced an increase that was enhanced by the addition of MB. ISO increased segment shortening, with a significant change in the control group. ISO increased regional force in both groups. The addition of MB increased force above ISO levels, with a significant change in the LVH group. ISO increased regional minute work (g·mm·min-1) (control, 1779 ± 428 to 2541 ± 500; LVH, 1157 ± 253 to 1839 ± 404) and O2 consumption. MB further increased regional work (control, 2993 ± 952; LVH, 2416 ± 853) and O2 consumption. ISO raised cyclic AMP (pmoles·g-1) (control, 468 ± 41 to 580 ± 84; LVH, 445 ± 43 to 562 ± 71) and had no effect on cyclic GMP (pmoles·g-1) (control, baseline 3.27 ± 0.22, ISO 2.87 ± 0.23; LVH, baseline 6.84 ± 1.12, ISO 5.66 ± 0.54). The addition of MB lowered cyclic GMP (control, 2.41 ± 0.26; LVH, 3.68 ± 0.35), but also increased cyclic AMP (control, 1021 ± 121; LVH, 1107 ± 134). Similar results were observed in control hearts using a specific soluble guanylate cyclase inhibitor (ODQ) in terms of changes in local work, O2 consumption, and cyclic nucleotides. Thus, at least part of the positive inotropic response to lowering cyclic GMP was mediated by changes in cyclic AMP in the current model. This was true in both control and LVH animals, although baseline cyclic GMP levels were higher, and a larger reduction in cyclic GMP was observed with MB in the LVH group.Key words: guanylate cyclase, coronary blood flow, myocardial shortening, myocardial work, myocardial O2 consumption, dog.
The effect of sinus node depression on heart rate variability in humans using zatebradine, a selective bradycardic agent
Authors: Khaykin Yaariv , Dorian Paul , Tang Anthony , Green M , Mitchell Jan , Wulffhart Zaev , Newman David
Published: April 2011

Zatebradine is a bradycardic agent with a selective effect on the pacemaker current in the sinus node. The effect of such drugs on heart rate variability is not known. Thirty-six patients without structural heart disease were randomly assigned to receive 10 mg of zatebradine i.v. (n = 24) or isotonic saline (n = 12). Heart rate variability (HRV) was recorded as power in the very low frequency (VLF, 0.003-0.040 Hz), low frequency (LF, 0.040-0.150 Hz), and high frequency (HF, 0.150-0.400 Hz) spectral bands as well as total power (TP, 0.003-0.400 Hz) during 5-min ECG acquisitions at baseline, 30, and 60 min following the start of the infusion. No change in heart rate variability was detected in the control group. Zatebradine significantly reduced heart rate variability at 60 min in all frequency bands: VLF (-12 ± 4%, p < 0.001), LF (-19 ± 4%, p < 0.001), and HF (-26 ± 5%, p < 0.001). The reduction in HRV following zatebradine is due to depression of sinus node response to all external stimuli and underscores the need for documentation of normal sinus node function in HRV research.Key words: zatebradine, sinus node, heart rate variability, HRV, autonomic nervous system.
The biochemical and pharmacological properties of a newly synthesized H+-K+ ATPase inhibitor, 2-dimethylamino-4,5-dihydrothiazolo[4,5:3,4]pyridol-[1,2-a]benzimidazole
Authors: Chung Young-Kuk , Chang Man-Sik , Kim Kyu-Bong , Sohn Sang-Kwon , Woo Tae-Wook , Lee Seok-Bong , Choi Wahn-Soo
Published: April 2011

This study was designed to determine the effect of a newly synthesized proton pump inhibitor, 2-dimethylamino-4,5-dihydrothiazolo[4,5:3,4]pyridol[1,2-a]benzimidazole (YJA20379-2), on gastric H+-K+ ATPase activity, acid secretion, and experimental gastroduodenal lesions or ulcers in rats. YJA20379-2 inhibited in a concentration-dependent manner the proton pump (H+-K+ ATPase) activity in isolated hog gastric mucosal microsomes, therefore, confirming its classification as a proton pump inhibitor. The inhibitory efficacy of YJA20379-2 on the proton pump was about eight times higher than that of omeprazole at pH 7.4. The activity of the inhibited enzyme was not restored by dilution and washout method, so this implied that the inhibition of YJA20379-2 is not reversible. YJA20379-2, given intraduodenally or orally, potently suppressed acid secretion in pylorus-ligated rats, with ED50 values of 3.6 and 7.7 mg·kg-1, respectively. Pretreatment with YJA20379-2 dose dependently protected the gastric mucosa from damage induced by absolute ethanol, water-immersion stress, indomethacin, and the duodenal mucosa from damage induced by mepirizole in rats, with ED50 values of 11.0, 21.0, 0.5, and 18.7 mg·kg-1, respectively. Repeated administration of YJA20379-2 also dose dependently accelerated spontaneous healing of acetic acid induced gastric ulcers. These results suggest that YJA20379-2 has potent antisecretory and antiulcer effects, which are exerted by suppression of H+-K+ ATPase activity in gastric parietal cells, such that YJA20379-2 may be useful for the clinical treatment of peptic ulcer diseases.Key words: antisecretion, cytoprotection, H+-K+ ATPase, YJA20379-2.
Influence of gender on post-tetanic potentiation in human dorsiflexors
Authors: O'Leary Deborah D , Hope Karen , Sale Digby G
Published: April 2011

Twitch contractions of the ankle dorsiflexors were evoked before and after 7 s of tetanic stimulation at 100 Hz in young women and men. Torque decreased more in men (18%) than in women (12%) during the tetanus. There was no gender difference in twitch peak torque potentiation over the 5-min post-tetanus. Potentiation was 42% (women) and 45% (men) at 5 s post-tetanus, and still present at 5 min (women 24%, men 25%). The immediate (5 s) shortening of twitch rise time was similar in women (14%) and men (13%), but during the 5-min men's rise time came to exceed whereas women's only approached pretetanus values (e.g., +9% vs. -1% at 5 min). The immediate decrease in half-relaxation time was also similar in women (24%) and men (22%); however, women's but not men's values remained less than pretetanus values for most of the 5-min period. Twitch rate of torque development increased similarly (75%) in women and men at 5 s, with no gender difference over 5 min. In contrast, rate of torque relaxation increased significantly only in men. Rate of torque development normalized to peak torque was similar in women and men pretetanus and increased similarly 5 s post-tetanus, but women had greater values through most of the 5-min post-tetanus. Normalized rate of torque relaxation was similar in women and men and not affected by tetanus. In the dorsiflexor muscles, young women and men show a similar amount and pattern of twitch force potentiation, but there are gender differences in time-related twitch contractile properties in the first 5 min after tetanus.Key words: contraction, muscle, twitch.
Estrogen administration, postexercise tissue oxidative stress and vitamin C status in male rats
Authors: Tiidus Peter M , Bombardier Eric , Hidiroglou Nick , Madere Rene
Published: April 2011

Estrogen can putatively act as an antioxidant and protect tissues from exercise-induced oxidative stress. To test the in vivo efficacy of estrogen, the effects of 2 weeks of daily estrogen (40 µg·kg-1 body weight beta-estradiol 3-benzoate) injection on indices of immediate postexercise oxidative stress and antioxidant status were determined in adult male rats, with and without 8 weeks of prior dietary vitamin E deprivation. The treadmill running protocol (60 min at 21 m·min-1, 12% grade) induced significant oxidative stress as indicated by muscle glutathione status. Estrogen administration had little effect on postexercise tissue glutathione status, superoxide dismutase and glutathione peroxidase activity, and vitamin E levels. Estrogen administration induced significant reductions in muscle, liver, and heart vitamin C concentrations following exercise, as well as in unexercised male rats. Tissue vitamin C loss was not directly mediated through liver glycogen or glutathione status. Thus, estrogen administration generally did not appear to influence postexercise tissue indices of oxidative stress or antioxidant status and may have contributed to a decline in overall antioxidant protection by inducing losses in tissue vitamin C content.Key words: glutathione, vitamin E, muscle, superoxide dismutase, glutathione peroxidase.
In situ study of the sarcoplasmic reticulum function in control and mdx mouse diaphragm muscle
Authors: Khammari A , Péréon Y , Baudet S , Noireaud J
Published: April 2011

Sarcoplasmic reticulum (SR) calcium handling in diaphragm was compared between mdx mice (7-8 weeks old) and age-matched controls. The total SR Ca2+ load was released from the SR by rapidly cooling muscle bundles from 22 to -1°C. The plateau amplitude of the rapid cooling contracture (RCC) was considered as an index of the SR Ca2+ content. The steady-state RCC amplitude was significantly lower by 50% in mdx bundles mainly because of a decreased capacity of the dystrophic diaphragm to generate maximal tension. There was no significant difference between either RCC time to peak or the time to half-relaxation of the transient, spike-like, contractile response induced by muscle rewarming. The recovery process of RCC was studied by using a paired RCC protocol. In both groups, at the shortest interval (10 s) between two RCCs, the amplitude of the second RCC was decreased by 25% compared with the first RCC. Increasing the time interval led to progressive monoexponential recovery of the second RCC with similar time constants in control and mdx diaphragm. These results indicate that the dystrophic process does not significantly alter SR Ca2+ uptake nor Ca2+ redistribution within the muscular cell.Key words: diaphragm, mdx, rapid cooling contracture, sarcoplasmic reticulum.
Endurance training alters antioxidant enzyme gene expression in rat skeletal muscle
Authors: Gore M , Fiebig R , Hollander J , Leeuwenburgh C , Ohno H , Ji L L
Published: April 2011

The effects of endurance training on gene expression of superoxide dismutase (SOD) and glutathione peroxidase (GPX) were investigated in type 2a and 2b skeletal muscles, as well as heart and liver, in the rat. Female Sprague-Dawley rats (4 months old, 300-320 g) were randomly divided into a trained (T, n = 11) and a control (C, n = 10) group and were pair fed a diet consisting of 66% cornstarch and 34% basal diet that contained all essential nutrients. Training was conducted on a treadmill at 25 m·min-1, 10% grade for 2 h per day, 5 days per week for 10 weeks, resulting in a 79% (p < 0.01) increase in citrate synthase activity in the deep portion of vastus lateralis muscle (DVL, type 2a). Cu-Zn SOD activity was 35% higher (p < 0.01) in DVL of T versus C rats, and Cu-Zn SOD mRNA abundance showed a 125% increase with training (p < 0.05). Cu-Zn SOD protein content was not altered in DVL, but increased significantly (p < 0.05) in the superficial portion of vastus lateralis (type 2b) with training. Trained rats showed a 66% higher (p < 0.05) Mn SOD protein content in DVL, but Mn SOD activity and mRNA abundance were not affected. Training also significantly increased GPX activity by 62% (p < 0.05), without changing its mRNA abundance, in the DVL. Heart and liver showed a 112 and 58% increase (p < 0.01) in Cu-Zn SOD mRNA abundance with training, respectively, but no other training adaptation was detected. These data indicate that endurance training can promote gene expression of muscle antioxidant enzymes in a fiber-specific manner. Training appears to upregulate Cu-Zn SOD mRNA abundance in a number of aerobic tissues, whereas Mn SOD and GPX induction observed in DVL may occur at the post-transcriptional levels.Key words: glutathione peroxidase, mRNA, skeletal muscle superoxide dismutase, training.
Bulbospinal serotonergic activity during changes in thyroid status
Authors: Henley William N , Bellush Linda L , Tressler Marc
Published: April 2011

A three-part study explored the basis for an interaction between changes in thyroid status and bulbospinal serotonin (5HT) metabolism. In experiment 1, three well-characterized models of primary hypothyroidism were all accompanied by significant increases in 5HT metabolism. In experiment 2, circulating thyroid hormone levels were experimentally varied from very low methimazole (Meth) treatment to very high (T3 implants: 2.5, 5.0, or 7.5 mg triiodothyronine). As in experiment 1, Meth led to elevated 5HT. Hyperthyroidism was accompanied by significant reductions in 5HT, while urinary norepinephrine excretion paralleled 5HT. In experiment 3, rats were subjected to Meth either 2 weeks before or after induction of diabetes with streptozotocin (Stz). Meth prevented Stz-associated reductions in 5HT and attenuated development of hyperphagia. Meth could not reverse established Stz-associated reduction in 5HT or hyperphagia, although both were slightly attenuated. Thus, although the first two experiments argue for a simple inverse relationship between circulating thyroid hormone levels and 5HT in the brain, experiment 3 demonstrated that Stz-associated decrements in 5HT could not be reversed by subsequent lowering of circulating thyroid hormone. Nor did accompanying measurements indicate that glycemic status or circulating levels of leptin were important predictors of 5HT. Thus the interaction between thyroid hormones and 5HT is both more subtle and more complex than previously thought.Key words: hypothyroidism, hyperthyroidism, serotonin, diabetes mellitus.
Role of insulin preincubation in the contractile reactivity of rat aortic rings
Authors: Rebolledo Alejandro , Milesi Verónica , Alvis Alicia Gomez , Rinaldi Gustavo J , Grassi de Gende Angela O
Published: April 2011

Preincubation with physiological concentrations of insulin affects contractile reactivity of isolated smooth muscle cells. We studied the effects of insulin on intact aortic rings of Wistar rats preincubated 1-2 h with 240 pM (I1) and 960 pM (I2) insulin with and without NO synthesis inhibition by Nomega-nitro-L-arginine methyl ester (L-NAME). Resting force was tripled by 0.1 mM L-NAME in control (C) and I1 groups, but not in I2 groups. I1 treatment decreased the tachyphylaxis to two successive 1 µM arginine vasopressin (AVP) stimulations. Single contractions elicited by 1 µM AVP, 1 µM angiotensin II (AngII), or 0.01 µM endothelin (ET1) were not affected by insulin preincubation in either maximal force (Fmax) or relaxation times. L-NAME enhanced Fmax of AngII contractions by about 75% in C, 120% in I1, and 74% in I2 groups; accordingly, it augmented the final steady-state force in C and I1 but not in I2. Similarly, L-NAME increased Fmax (30-40%) of AVP and ET1 contractions in C and I1 groups but failed to do so in contractions of I2 group. Results obtained with 10 µM indomethacin suggest that this is due to insulin stimulation of prostacyclin effects.Key words: insulin, rat aorta, NO inhibition, arginine vasopressin, angiotensin II, endothelin 1, prostacyclin.
Exercise promotes a subcellular redistribution of calcium-stimulated protease activity in striated muscle
Authors: Arthur Gavin D , Booker Timothy S , Belcastro Angelo N
Published: April 2011

The aims of this study were (i) to investigate whether the contractile activity associated with running increases calcium-stimulated, calpastatin-inhibited protease activity (calpain-like) in a time-dependent manner and (ii) to determine whether the changes, if any, are proportionately distributed between soluble (cytosolic) and particulate (bound) fractions of striated muscle in vivo. Calcium-dependent, calpastatin-inhibited caseinolysis (i.e., calpain-like activity) was measured in control and exercised rats (25 m/min, 0% grade) at 2, 5, 15, 30, and 60 min. Total calpain-like activity in skeletal muscle increased by 26% (13.2 ± 1.3 vs. 17.9 ± 2.2 U/g wet wt.) (p < 0.05) after running (60 min), accompanied by an increased activity in the particulate fraction. In cardiac muscle, exercise (60 min) increased total calpain-like activity by 33% (p < 0.05), which was attributable to increases in both the cytosolic and particulate fractions. Both tissues responded with an early (2-5 min) activation of total calpain-like activity (p < 0.05), supported by early increases for particulate fractions from skeletal muscle; whereas for cardiac muscle, a noticeable early drop (p < 0.05) occurred in the particulate fraction. Minimal changes were observed for total, cytosolic, and particulate fractions of noncontracting tissue (i.e., liver). The results of this study support the hypothesis that the total calpain-like activity increases associated with level running occur early on with exercise and that the increases are accompanied by changes in the redistribution of soluble to particulate fractions. The changes would set the stage for enhanced rates of protein degradation known to occur in striated muscle with exercise.Key words: nonlysosomal proteases, calcium-dependent proteolysis, muscle damage.
Photoperiodic control of the maintenance and termination of larval diapause in Wyeomyia smithii (Coq.) (Diptera: Culicidae) with notes on oogenesis in the adult female
Authors: Smith Stephen M. , Brust Reinhart A.
Published: April 2011

Some aspects of overwintering and oogenesis in the pitcher-plant mosquito, Wyeomyia smithii (Coq.), were examined. The species was shown to overwinter in a diapause state as a third-instar larva. The diapausing larvae overwinter within the frozen ice cores of the host plant but they were nevertheless shown to be intolerant of prolonged periods of freezing at temperatures only a few degrees below 0 °C. The winter survival of the species probably depends almost entirely on the insulating benefits of a snow cover. Larval diapause was stable under short-day conditions but was very rapidly broken when the larvae were exposed to long-day photoperiods. The critical photoperiod required to break larval diapause in a population from the Kenora region of Ontario was between [Formula: see text] and 15 h of light per diem. This critical photoperiod did not change during a prolonged period of overwintering. Larvae which experienced 5 or fewer long-day cycles remained in diapause when they were returned to short-day conditions but diapause was irreversibly broken in larvae exposed to 8 or more long-day cycles in succession. Data on growth rates of larvae as a function of temperature and photoperiod were used to predict the seasonal cycle of W. smithii in northwestern Ontario where the species is probably restricted to a maximum of two generations per year. All females of W. smithii were autogenous for the first ovarian cycle and adult diets of carbohydrate did not affect fecundity. Unlike other mosquitoes, the female of W. smithii was found to be precocious, emerging with the ovarian follicles already initiated with development of the follicles up to stage IIIa of Christophers.
Seal milk. Π. Harp seal (Pagophilus groenlandicus) milk: effects of stage of lactation on the composition of the milk
Authors: Horn D. R. Van , Baker β. Ε.
Published: April 2011

A harp seal and her pup were caught on the ice floes in the Gulf of St. Lawrence and were kept in captivity for 16 days. Milk was collected from the seal 2, 3, 5, 6, and 16 days postpartum. The gross composition and the fatty acid and mineral constitution of the milk were determined. Both the fat and the protein contents were minimal on the 16th day postpartum. The fatty acid composition of the fat did not follow a definite pattern of change during the lactation period.
A new species from Mexico of the Nearctic genus Percymoorensis, and remarks on the family Haemopidae (Hirudinoidea)
Authors: Richardson Laurence R.
Published: April 2011

P. caballeroi sp. nov. has bimyomeric megamorphic median regions on the reproductive systems, both extended in the paramedian chambers of the body cavity. It differs from P. marmoratis in having pale maculae forming a simple somital pattern, unequal annuli on the midnephric somites, and a postanal chamber. The genera Philobdella and Semiscolex are excluded from the Haemopidae, and subfamilies Haemopinae and Mollibdellinae are proposed.
Axenic production of ova by Enchytraeus fragmentosus (Bell)
Authors: Hamilton Mary , Hess Roberta T.
Published: April 2011

The microannelid Enchytraeus fragmentosus was found to be capable of sexual reproduction under axenic culture methods described. Axenic clones of this annelid reproducing by sexual and asexual methods are now available.
Scale effects in the kinematics and dynamics of swimming leeches
Authors: Jordan Christopher E
Published: April 2011

Slender-bodied organisms swimming with whole-body undulations exhibit what appears to be a high degree of kinematic parameter conservation, which is independent of body size. However, organisms of very different sizes swim in fundamentally different physical realms, owing to the relative scaling of viscous and inertial fluid stresses as a function of size and speed. In light of the size-dependent fluid forces, the kinematic constancy suggests three hypotheses: (1) swimming organisms adopt a single "ideal" swimming mode requiring the modification of muscle forces or motor patterns through ontogeny, (2) swimming kinematics are determined predominantly by the passive mechanical interaction of the body and the fluid, resulting in a single swimming mode independent of absolute body size, or (3) while undulatory swimming kinematics may be similar between organisms, there are important size-dependent kinematic differences. In this study, I address this issue by examining the swimming kinematics and dynamics of the medicinal leech Hirudo medicinalis L. as a function of body size. Over a 5-fold increase in body length, the relative amplitude of body undulations during swimming did not change; however, swimming speed, propulsive wave speed, and propulsive wave frequency all decreased, while propulsive wave number increased slightly, strongly supporting hypothesis 2. To determine the source of the observed size-dependent swimming kinematics, I manipulated the dynamic viscosity of the organism's fluid environment to alter the constraints placed on swimming behavior by the physical surroundings. In the elevated-viscosity treatment, all kinematic parameters changed in the opposite direction to that predicted by hypothesis 2, rejecting both the idea that swimming kinematics are simply determined by passive mechanical interactions and that leeches have a target swimming mode under active control.
Differential effects of claudin-3 and claudin-4 on alveolar epithelial barrier function
Authors: Mitchell Leslie A. , Overgaard Christian E. , Ward Christina , Margulies Susan S. , Koval Michael
Published: April 2011

Alveolar barrier function depends critically on the claudin family tight junction proteins. Of the major claudins expressed by alveolar epithelial cells, claudin (Cldn)-3 and Cldn-4 are the most closely related by amino acid homology, yet they differ dramatically in the pattern of expression. Previously published reports have shown that Cldn-3 is predominantly expressed by type II alveolar epithelial cells; Cldn-4 is expressed throughout the alveolar epithelium and is specifically upregulated in response to acute lung injury. Using primary rat alveolar epithelial cells transduced with yellow fluorescent protein-tagged claudin constructs, we have identified roles for Cldn-3 and Cldn-4 in alveolar epithelial barrier function. Surprisingly, increasing expression of Cldn-3 decreased alveolar epithelial barrier function, as assessed by transepithelial resistance and dye flux measurements. Conversely, increasing Cldn-4 expression improved alveolar epithelial transepithelial resistance compared with control cells. Other alveolar epithelial tight junction proteins were largely unaffected by increased expression of Cldn-3 and Cldn-4. Taken together, these results demonstrate that, in the context of the alveolar epithelium, Cldn-3 and Cldn-4 have different effects on paracellular permeability, despite significant homology in their extracellular loop domains.
Reliability of Prehospital Real-Time Cellular Video Phone in Assessing the Simplified National Institutes of Health Stroke Scale in Patients With Acute Stroke
Authors: Gonzalez Manuel A. , Hanna Nicholas , Rodrigo Maria E. , Satler Lowell F. , Waksman Ron
Published: April 2011

Background and Purpose—

The National Institutes of Health Stroke Scale (NIHSS) is the gold standard to assess patients with acute stroke. We aimed to examine the feasibility and reliability of prehospital real-time cellular video phone (VP) in performing the NIHSS.

Methods—

Forty physicians prospectively performed a simplified NIHSS (sNIHSS) on a standardized patient remotely using VP with the assistance of a bedside emergency medical technician and later performed a bedside examination. We tested the hypothesis that there is high reliability between these 2 methods. Physicians were timed and sNIHSS scores were recorded. Finally, physicians were asked to rate the VP technology.

Results—

A total of 480 pair comparisons of the sNIHSS scores between the VP and bedside examination were generated. After adjusting for the physician's specialty, level of training, and certification status, there was a strong positive linear correlation (
r
=0.97,
P
<0.01) between the 2 methods with high average physician reliability (0.99; 95% CI, 0.992 to 0.995). The mean sNIHSS scores using VP and bedside examination were not different (6.82±1.06 versus 6.63±0.98;
P
=0.08). The mean time to perform the sNIHSS using VP was approximately 38 seconds longer than the bedside examination (3.38±0.77 versus 2.93±0.83 minutes;
P
=0.006).

Conclusions—

The VP is a feasible, reliable, and timely tool with the potential for remotely assessing the sNIHSS for patients presenting with acute stroke and may expedite the initial evaluation and treatment strategies.
Using Recombinant Tissue Plasminogen Activator to Treat Acute Ischemic Stroke in China
Authors: Wang Yilong , Liao Xiaoling , Zhao Xingquan , Wang David Z. , Wang Chunxue , Nguyen-Huynh Mai N. , Zhou Yong , Liu Liping , Wang Xianwei , Liu Gaifen , Li Hao , Wang Yongjun
Published: April 2011

Background and Purpose—

Little is known about intravenous recombinant tissue plasminogen activator (rtPA) use in China. By accessing the Chinese National Stroke Registry (CNSR), the rate of intravenous rtPA use was reviewed. We specifically examined the issues of prehospital and in-emergency department delay and compared them with the published data from developed countries.

Methods—

Funded by Chinese government, CNSR is the only nationwide stroke registry that includes 132 urban hospitals. All patients eligible for intravenous rtPA were included for analysis. We then compared the onset-to-needle time and door-to-needle time in the emergency department in China with those in developed countries.

Results—

From September 2007 to August 2008, 14 702 patients with ischemic stroke were entered into CNSR. Among 11 675 patients with known time of stroke onset, 2514 (21.5%) presented to the emergency department within 3 hours, 1469 (12.6%) were eligible for thrombolytic treatment, and 284 (2.4%) were finally treated, 181 (1.6%) of them with intravenous rtPA. The median onset-to-needle time was 180 (interquartile range, 150 to 228) minutes; the median door-to-needle time was 116 (interquartile range, 70 to 150) minutes; the median imaging-to-needle time was 90 (interquartile range, 60 to 129) minutes. Patients who were younger, presented to the emergency department quicker, with higher National Institutes of Health Stroke Scale scores, having higher income, and better education had a better chance of receiving intravenous rtPA.

Conclusions—

Approximately 1 in 5 patients with stroke presenting within 3 hours received thrombolytic therapy. The onset-to-needle time, door-to-needle time, and especially imaging-to-needle time were significantly longer than those in developed countries. Reducing prehospital and in-emergency department response time would help increase intravenous rtPA use in China.
Modeling the Predictive Validity of SAT Mathematics Items Using Item Characteristics
Authors: Kobrin Jennifer L. , Kim YoungKoung , Sackett Paul R.
Published: April 2011

There is much debate on the merits and pitfalls of standardized tests for college admission, with questions regarding the format (multiple-choice vs. constructed response), cognitive complexity, and content of these assessments (achievement vs. aptitude) at the forefront of the discussion. This study addressed these questions by investigating the relationship between SAT Mathematics (SAT-M) item characteristics and the item’s ability to predict college outcomes. Using multiple regression, SAT-M item characteristics (content area, format, cognitive complexity, and abstract/concrete classification) were used to predict three outcome measures: the correlation of item score with first-year college grade point average, the correlation of item score with mathematics course grades, and the percentage of students who answered the item correctly and chose to major in a mathematics or science field. Separate models were run including and excluding item difficulty and discrimination as covariates. The results revealed that many of the item characteristics were related to the outcome measures and that item difficulty and discrimination had a mediating effect on several of the predictor variables, particularly on the effects of nonroutine/insightful items and multiple-choice items.
The 1-in-X Effect on the Subjective Assessment of Medical Probabilities
Authors: Pighin Stefania , Savadori Lucia , Barilli Elisa , Cremonesi Laura , Ferrari Maurizio , Bonnefon Jean-François
Published: April 2011

Among numerical formats available to express probability, ratios are extensively used in risk communication, perhaps because of the health professional’s intuitive sense of their clarity and simplicity. Moreover, health professionals, in the attempt to make the data more meaningful, tend to prefer proportions with a numerator of 1 and shifting denominators (e.g., 1 in 200) rather than equivalent rates of disease per unit of population exposed to the threat (e.g., 5 in 1000). However, in a series of 7 experiments, it is shown that individual subjective assessments of the same probability presented through proportions rather than rates vary significantly. A 1-in- X format (e.g., 1 in 200) is subjectively perceived as bigger and more alarming than an N-in- X* N format (e.g., 5 in 1000). The 1-in- X effect generalizes to different populations, probabilities, and medical conditions. Further-more, the effect is not attenuated by a communicative intervention (verbal analogy), but it disappears with an icon array visual aid.
Importance of Independent Measurement of Width and Length of Lateral Meniscus During Preoperative Sizing for Meniscal Allograft Transplantation
Authors: Yoon Jung-Ro , Kim Taik-Sun , Wang Joon-Ho , Yun Ho-Hyun , Lim Hyungtae , Yang Jae-Hyuk
Published: April 2011

Background: Successful meniscus transplantation depends on an accurate sizing of the meniscal allograft. Although accurate sizing of the meniscal allograft is crucial during meniscus transplantation, the accuracy of meniscal measurement methods is still in debate.

Purpose: This study was undertaken to evaluate the relationship between the width and length of the lateral meniscus. These anatomic dimensions were also evaluated in the context of the patient’s height, weight, gender, and body mass index (BMI).

Study Design: Descriptive laboratory study.

Methods: Ninety-one samples of fresh lateral meniscus were obtained during total knee arthroplasty. The samples were obtained carefully without injuring the meniscus itself and the bony attachment sites. For each lateral meniscus, the anatomic dimensions (width [LMW] and length [LML]) were recorded. The height, weight, gender, and BMI of the patients were also recorded. The Pearson correlation and multivariate and linear regression analysis were applied for each variable. The accuracy was defined as those measures that fell within 10% of the original size. A P value ≤ .05 was considered significant.

Results: The mean LMW was 30.7 mm (standard deviation [SD] = 3.5) and 27.0 mm (SD = 2.6) for men and women, respectively. The mean LML was 33.7 mm (SD = 4.3) and 30.8 mm (SD = 2.6) for men and women, respectively. Thirty-nine samples (42.5%) showed LMW measurements within a 10% difference of LML, whereas 50 samples (55%) showed an LMW greater than a 10% difference of LML. Although there were correlations between LML with LMW in men and correlations between weight and LMW with LML in women, the accuracy for the derived linear regression formulas was 3%, 9%, and 12%, respectively.

Conclusion: The length cannot be predicted accurately from the width of the lateral meniscus. The height, weight, gender, and BMI failed to estimate the dimensions of the lateral meniscus. Therefore, it is essential to measure the width and length separately and match it with the allograft with other size measuring methods.

Clinical Relevance: This study emphasizes the importance of measuring the width and length of the lateral meniscus independently during preoperative sizing for a meniscal allograft transplantation procedure. The height, weight, gender, and body mass index may not be reliable parameters for estimating the size of the meniscus.
Winners Love Winning and Losers Love Money
Authors: Kassam Karim S. , Morewedge Carey K. , Gilbert Daniel T. , Wilson Timothy D.
Published: April 2011

Salience and satisfaction are important factors in determining the comparisons that people make. We hypothesized that people make salient comparisons first, and then make satisfying comparisons only if salient comparisons leave them unsatisfied. This hypothesis suggests an asymmetry between winning and losing. For winners, comparison with a salient alternative (i.e., losing) brings satisfaction. Therefore, winners should be sensitive only to the relative value of their outcomes. For losers, comparison with a salient alternative (i.e., winning) brings little satisfaction. Therefore, losers should be drawn to compare outcomes with additional standards, which should make them sensitive to both relative and absolute values of their outcomes. In Experiment 1, participants won one of two cash prizes on a scratch-off ticket. Winners were sensitive to the relative value of their prizes, whereas losers were sensitive to both the relative and the absolute values of their prizes. In Experiment 2, losers were sensitive to the absolute value of their prize only when they had sufficient cognitive resources to engage in effortful comparison.
In Praise of Vagueness
Authors: Mishra Himanshu , Mishra Arul , Shiv Baba
Published: April 2011

Is the eternal quest for precise information always worthwhile? Our research suggests that, at times, vagueness has its merits. Previous research has demonstrated that people prefer precise information over vague information because it gives them a sense of security and makes their environments more predictable. However, we show that the fuzzy boundaries afforded by vague information can actually help individuals perform better than can precise information. We document these findings across two laboratory studies and one quasi–field study that involved different performance-related contexts (mental acuity, physical strength, and weight loss). We argue that the malleability of vague information allows people to interpret it in the manner they desire, so that they can generate positive response expectancies and, thereby, perform better. The rigidity of precise information discourages desirable interpretations. Hence, on certain occasions, precise information is not as helpful as vague information in boosting performance.
Friendships
Authors: Scharbach Dan
Published: April 2011

A series of articles regarding management techniques.