bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biophysics of Underwater Hearing in Anuran Amphibians
Authors: Hetherington Thomas E. , Lombard R. Eric 
Published: April 2021

ABSTRACTA standing wave tube apparatus was used to determine the biophysical basis of underwater hearing sensitivity in 3 species of Rana and in Xenopus laevis. A speaker inside the base of a vertical, water-filled 3 m steel pipe produced standing waves. Pressure and particle motion were measured with a hydrophone and geophone respectively and were spatially 90° out of phase along the length of the tube. Microphonic responses were recorded from the inner ear of frogs lowered through pressure and particle motion maxima and minima. The air-filled lungs of whole frogs produced distortions of the sound field. Preparations of heads with only an air-filled middle ear produced little distortion and showed clear pressure tracking at sound intensities 10–20 dB above hearing thresholds from 200–3000 Hz. Filling the middle ear with water decreased or abolished microphonic responses. Severing the stapes reduced responses except at certain frequencies below about 1000 Hz which varied with body size and likely represent resonant frequencies of the middle ear cavity. We conclude that the frog species examined respond to underwater sound pressure from about 200–3000 Hz with the middle ear cavity responsible for pressure transduction.
Light Organ and Eyestalk Compensation to Body Tilt in the Luminescent Midwater Shrimp, Sergestes Similis
Authors: Latz Michael I. , Case James F. 
Published: April 2021

ABSTRACT
The posterior light organ and eyestalk of the midwater shrimp, Sergestes similis Hansen, are capable of 140° of angular movement within the body during pitch body tilt, maintaining the organs at near horizontal orientations. Counter-rotations compensate for 74–80% of body inclination.
These responses are statocyst mediated. Unilateral statolith ablation reduces compensation by 50%. There is no evidence for either homolateral or contralateral control by the single functioning statocyst. Bilateral lith ablation abolishes counter-rotation. Light organ and eyestalk orientations are unaffected by the direction of imposed body tilt.
Bioluminescence is emitted downward from horizontal animals with an angular distribution similar to the distribution of oceanic light. The amount of downward directed luminescence in tilted animals decreases at large angles of body inclination due to less than total compensation by the light organs.
Eye turning towards a light source is induced by upward-directed illumination. The resulting change in eyestalk orientations never amounts to more than 25°. The turning is abolished by bilateral statolith ablation. Downward directed illumination, comparable in intensity to oceanic light, generally does not generate significant eye turning.
Light organ orientations remain unaffected by directional illumination, both before and after bilateral statolith ablation.
The compensatory counter-rotations by the posterior light organ and eyestalk suggest that counter-illumination by S. similis remains effective in inclined animals.
Ion-dependent Viscosity of Holothurian Body Wall and its Implications for the Functional Morphology of Echinoderms
Authors: Eylers John P. 
Published: April 2021

ABSTRACT
Dermis from the holothurian Thyone inermis was subjected to constant load and its rate of plastic deformation (creep) was used to calculate tissue viscosity. During these tests the material was bathed in distilled water, sea water, or solutions of sodium, potassium, calcium, and magnesium salts in various combinations. Distilled water caused a threefold increase in viscosity which was reversed by sea water. Sodium and potassium decreased viscosity, while calcium and magnesium in combination with sodium increased it. Ionic cross-links shielded by monovalent ions but facilitated by divalent cations are proposed to explain this behaviour, and the relationship between this and other anomalies of echinoderm connective tissue physiology is discussed.
The acid-base responses of gills and kidneys to infused acid and base loads in the channel catfish,Ictalurus punctatus
Authors: Cameron J. N. , Kormanik G. A. 
Published: April 2021

ABSTRACTAcid and base loads infused into the dorsal aorta of the freshwater channel catfish (Ictalurus punctatus Rafinesque) were excreted by both gills and kidneys. The gills excreted 2–3 times as much as the kidneys.After a 2 mmol.kg−1 load of NaHCO3, the gills excreted 50% of the net OH- load in the first 5 h, while the kidneys excreted 18% in the first 6 h. After a 2 mmol.kg−1 load of NH4C1, the gills excreted 32% of the load in 6 h, and 16% was excreted renally in 20 h. There was no evidence of tissue damage after either NaHCO3 or NH4C1 infusions, whereas infusion of 2 mmol. kg−1 HC1 or 1 mmol. kg−1 of L( + )-lactic acid caused significant kidney damage and extensive tissue necrosis within 24 h.After both NaHCO3 and NH4C1 infusions, the majority of the load had been transferred to the intracellular compartment within 2 h. From there it was excreted slowly, presumably by transfer back through the extracellular compartment. Due to the relative compartment volumes and buffer values, the change in intracellular pH was less than 0·05 units, while the blood pH was changed by as much as 0·3 units.
The central nervous origin of the swimming motor pattern in embryos ofXenopus laevis
Authors: Kahn J. A. , Roberts A. 
Published: April 2021

ABSTRACTRhythmic motor nerve activity was recorded in stage 37/38 Xenopus embryos paralysed with curare. The activity was similar to the swimming motor pattern in the following ways: cycle period (40–125 ms), alternation of activity on either side of a segment, rostro-caudal phase lag. Episodes of rhythmic motor activity could be evoked by stimuli that evoke swimming and inhibited by stimuli that normally inhibit swimming. On this basis we conclude that the swimming motor pattern is generated by a central nervous mechanism and is not dependent on sensory feedback.In addition to the swimming pattern, another pattern of motor activity (‘synchrony’) was sometimes recorded in curarized embryos. In this, the rhythmic bursts on either side of a segment occurred in synchrony, and the rhythm period (20–50 ms) was half that in swimming. This was probably not an artifact of curarization as there were indications of a similar pattern in uncurarized embryos. Its function remains unclear.
Characterization of Lymnaea Neurones by determination of Action Potential Trajectories
Authors: Winlow W. , Holden A. V. , Haydon P. G. 
Published: April 2021

ABSTRACT
Phase plane techniques have been used to demonstrate that identifiable neurones of Lymnaea stagnalis may be characterized by their action potential trajectories. These trajectories are consistent from preparation to preparation, but may be altered by strong synaptic inputs or by injection of current into neurones. There is a pronounced hysteresis in the maximum rates of depolarization and the maximum rates of repolarization of many cells following a period of hyperpolarization. Curves relating and to injected current have been constructed for each neurone type investigated and may be used to identify the neurones. We conclude that phase plane portraits of action potentials together with measures of and are useful in identification of neurones when structural criteria are not available.
Regulation of Blood Oxygen Affinity in the Australian BlackfishGadopsis Marmoratus
Authors: Dobson G. P. , Baldwin J. 
Published: April 2021

ABSTRACTThe regulation of whole blood oxygen affinity in the freshwater black-fish Gadopsis marmoratus Richardson has been examined, and correlations made between oxygen-binding properties and the habitat and swimming behaviour of the fish. Blackfish whole blood has a low oxygen affinity relative to other fish bloods reported in the literature. This is not due to a low oxygen affinity of the stripped haemoglobins, but arises from interactions between haemoglobin and intraerythrocytic modulators. The presence of high concentrations of ATP, and to a lesser extent GTP, in the erythrocyte, together with the effect of these nucleoside triphosphates on the oxygen affinity of haemoglobin solutions at physiological NTP: Hb4 molar ratios, demonstrates that this class of compounds is a major regulator of oxygen affinity in blackfish blood. The oxygen affinities of whole blood and haemoglobin solutions are sensitive to pH, with haemoglobin solutions displaying a relatively large alkaline Bohr coefficient of-– 1·05 over the physiologically relevant pH range of 6·5–7·0. Although increasing lowers the oxygen affinity of whole blood, it does so only through the effect on pH, as pH-buffered haemoglobin solutions show no oxygen-linked CO2 binding. This lack of oxygen-linked CO 2 binding has not been reported for any other naturally occurring vertebrate haemoglobins. Muscle morphology and biochemistry, and behavioural observations, indicate that the blackfish uses anaerobic energy metabolism during rapid swimming and in recovery. It is concluded that the oxygen-binding properties of blackfish blood reflect adaptations for maintaining adequate tissue oxygenation for animals at rest and during slow sustained swimming in waters of high oxygen tensions.
Metabolic Support of Chloride-dependent Short-Circuit Current Across Locust Rectum*
Authors: Chamberlin M. , Phillips J. E. 
Published: April 2021

ABSTRACTRecta of desert locusts were short-circuited and depleted of endogenous substrates by exposing them to saline containing cyclic AMP but no metabolites. Individual substrates were then added to substrate-depleted recta and the change in short-circuit current (Isc) monitored. Proline or glucose (50 mm) caused by far the largest increase in Isc of all substrates tested. Stimulation of the /sc by proline was not dependent upon external sodium, but did require external chloride. Physiological levels of proline also caused a large increase in Isc, while physiological levels of glucose produced a much smaller stimulation. Over 90% of the proline-dependent Isc stimulation can be produced by adding 15 mm proline solely to the lumen side of the tissue. These results are discussed with regard to rectal oxidative metabolism and availability of metabolic substrates in vivo. High levels of proline in Malpighian tubule fluid are probably the major substrate source for rectal Cl- transport.
Do the Extraocular Muscles in the Carp Compensate for Eye Displacements Induced by Respiratory Movements?
Authors: Jüch P. J. W. 
Published: April 2021

ABSTRACTThe eyes in normally respiring carp are induced by elements of the respiratory pumping system to make small displacements in phase with the respiratory cycle. The ocular movements were studied by film analysis during the normal respiratory cycle and the cough. In the course of the movement, the optic axis remains nearly parallel to its starting position. This results in a smaller retinal image shift than would be produced by angular movements.Electromyography of the extraocular muscles showed that the external rectus and superior oblique muscles contribute to image stabilization during strong respiration, and the external rectus and the superior oblique muscles contribute during the cough.
Responses to Hypersaline Exposure in the Euryhaline CrayfishPacifastacus Leniusculus
Authors: Wheatly Michèle G. , McMahon B. R. 
Published: April 2021

ABSTRACTHaemolymph iono- and osmoregulation and acid-base balance were recorded after 48 h exposure at 15 °C to a range of increasing ambient salinities (0,25, 50 and 75% seawater) in the euryhaline crayfish Pacifastacus leniusculus (Dana). Except for K+, concentrations of all measured inorganic ions and osmolality were significantly elevated in 50 and 75 % SW. When compared with ambient changes there was evidence of a transition from hyper- to hypoionic regulation above 44 % SW. Ca2+ was regulated for a constant blood-medium difference. A progressive reduction in total CO2 was recorded ; pH was maintained except in 75% SW where a haemolymph acidosis developed. To permit calculation of CO2 tension carbon dioxide solubility coefficient and the apparent first dissociation constant of carbonic acid were experimentally determined in vitro. decreased progressively with acclimation salinity but was unaffected by circulating protein. decreased as a function both of physiological pH and increasing haemolymph ionic strength. calculated using these empirical constants, progressively decreased with high-salinity acclimation. The resulting ‘hypocapnic alkalosis’ was partially offset by a metabolic acidosis, whose correlation with extracellular anisosmotic and intracellular isosmotic regulation is discussed.
Datengetriebene Geschäftsmodelle: Konzeptuelles Rahmenwerk, Praxisbeispiele und Forschungsausblick
Authors: Strahringer Susanne , Wiener Martin 
Published: April 2021

ZusammenfassungDatengetriebene Geschäftsmodelle (DGGM) vereinen zwei zentrale Trends des digitalen Zeitalters: die steigende Bedeutung von („Big“-)Daten und den zunehmenden Fokus auf das Geschäftsmodell als zentrale Gestaltungsebene. Nichtsdestotrotz sind die konzeptuellen Grundlagen und spezifischen Eigenschaften entsprechender Geschäftsmodelle bislang nur unzureichend erforscht und systematisiert. Basierend auf relevanten Vorarbeiten stellen wir in diesem Grundlagenbeitrag drei wesentliche Typen von DGGM vor (Datennutzer, Datenlieferanten und Datenbefähiger) und geben einen Überblick über zentrale „datengetriebene“ Konzepte, die wir in ein konzeptuelles Rahmenwerk zur weiterführenden Charakterisierung von DGGM integrieren. Die Anwendbarkeit und Nützlichkeit der drei DGGM-Typen und des entwickelten Rahmenwerks illustrieren wir anhand von drei Praxisbeispielen (KAESER, Shell Telematics und Celonis). Der Beitrag schließt mit einer Diskussion von vielversprechenden, thematischen Ansatzpunkten für zukünftige Forschungsarbeiten zu DGGM.
Metaheuristic algorithms for one-dimensional bin-packing problems: A survey of recent advances and applications
Authors: Munien Chanaleä , Ezugwu Absalom E. 
Published: April 2021

AbstractThe bin-packing problem (BPP) is an age-old NP-hard combinatorial optimization problem, which is defined as the placement of a set of different-sized items into identical bins such that the number of containers used is optimally minimized. Besides, different variations of the problem do exist in practice depending on the bins dimension, placement constraints, and priority. More so, there are several important real-world applications of the BPP, especially in cutting industries, transportation, warehousing, and supply chain management. Due to the practical relevance of this problem, researchers are consistently investigating new and improved techniques to solve the problem optimally. Nature-inspired metaheuristics are powerful algorithms that have proven their incredible capability of solving challenging and complex optimization problems, including several variants of BPPs. However, no comprehensive literature review exists on the applications of the metaheuristic approaches to solve the BPPs. Therefore, to fill this gap, this article presents a survey of the recent advances achieved for the one-dimensional BPP, with specific emphasis on population-based metaheuristic algorithms. We believe that this article can serve as a reference guide for researchers to explore and develop more robust state-of-the-art metaheuristics algorithms for solving the emerging variants of the bin-parking problems.
Chromate and molybdate pigments
Authors: Pfaff Gerhard 
Published: April 2021

AbstractChromate and molybdate pigments are representatives of the inorganic yellow, orange and red pigments. They are characterized by excellent optical and application properties in particular regarding brightness of shade, hiding power, tinting strength, and weather fastness. The declining use of lead- and chromate-containing materials in the last decades is a result of the environmental discussion and the development of less problematic substitute products, especially of bismuth vanadate and high-value organic, temperature-stable yellow and red pigments.
Mitogen-Activated Protein Kinase Phosphorylation in Kidneys of βs Sickle Cell Mice
Authors: KIROYCHEVA MILITZA , AHMED FAYYAZ , ANTHONY GILLIAN M. , SZABO CSABA , SOUTHAN GARRY J. , BANK NORMAN 
Published: April 2021

Abstract.
Previous studies in βs sickle cell mice demonstrated renal immunostaining for nitrotyrosine, which is putative evidence of peroxynitrite (ONOO-) formation. ONOO- is known to nitrate tyrosine residues of various enzymes, thereby interfering with phosphorylation and inactivating them. The present study examined the state of phosphorylation of mitogen-activated protein (MAP) kinase signal transduction enzymes, i.e., p38, c-Jun NH2-terminal kinase (JNK), and extracellular signal-regulated kinase (ERK). Western blot performed with antibodies directed against specific phosphorylated threonine/tyrosine residues of these enzymes demonstrated reduced phosphorylation of renal p38 and a trend toward reduced phosphorylation of ERK. In contrast, phosphorylation of renal JNK was markedly increased compared with normal mice. The abundance of MAP kinase phosphatase-1 (MKP-1), a key upstream enzyme that modulates phosphorylation of MAP kinases, was not different in βs
versus normal mice. To determine whether nitration of tyrosine by ONOO- was responsible for reduced phosphorylation of p38 and ERK, mercaptoethylguanidine (MEG), a compound known to reduce inducible isoform of nitric oxide synthase activity and to scavenge ONOO-, was administered to βs mice for 5 d. MEG was found to restore phosphorylation of p38 and ERK toward normal levels. These observations provide evidence that ONOO- (or closely related reaction products of NO) contributes to dephosphorylation of p38 and ERK, and presumably reduces activity of these enzymes. The increased phosphorylation of JNK, which suggests activation of this signaling pathway by extracellular stress signals, may play a role in apoptosis in the kidneys of these mice. The changes in phosphorylation of MAP kinase pathways found in this study could have important consequences for regulation of nuclear transcription factors, and thus renal function and pathology in sickle cell kidneys.
C-Terminal Parathyroid Hormone-Related Protein Increases Vascular Endothelial Growth Factor in Human Osteoblastic Cells
Authors: ESBRIT PEDRO , ALVAREZ-ARROYO MARIA VICTORIA , DE MIGUEL FERNANDO , MARTIN OLGA , MARTINEZ MARIA EUGENIA , CARAMELO CARLOS 
Published: April 2021

Abstract.
The N-terminal region of parathyroid hormone (PTH) and PTH-related protein (PTHrP) interacts with a common PTH/PTHrP receptor in osteoblasts. These cells synthesize PTHrP, but its role in bone turnover is unclear. Intermittent treatment with N-terminal PTHrP or PTH stimulates bone growth in vivo, possibly by increasing local bone factors. In addition, C-terminal PTHrP (107-139), which does not bind to the PTH/PTHrP receptor, appears to affect bone resorption in vivo and in vitro, although its effect on bone formation in vivo remains controversial. Bone angiogenesis is an often overlooked but critical event in the process of bone remodeling. Recently, PTH (1-34) has been shown to induce gene expression of vascular endothelial growth factor (VEGF), a potent angiogenic factor, by osteoblastic cells. However, no data are available on the effect of PTHrP (107-139) on VEGF expression in these cells. Using semiquantitative reverse transcription followed by PCR, we found that PTHrP (107-139), between 10 nM and 1 pM, increased VEGF mRNA in human osteoblastic (hOB) cells from trabecular bone. This effect of this agonist, at 10 nM, was maximal (fivefold for VEGF165, and twofold for VEGF121, compared to control) within 1 to 4 h. This effect was similar to that induced by PTHrP (1-34) in these cells, as well as in human osteosarcoma MG-63 cells, using Northern blot analysis. Moreover, the effect of both peptides, added together at 100 pM, was not higher than that observed with each peptide alone in hOB cells. The effects of PTHrP (107-139) and that of PTHrP (1-34) were abolished by actinomycin D in hOB cells. In these cells, the protein kinase C inhibitor staurosporine, but not the protein kinase A inhibitor H89, inhibited the increase in VEGF mRNA induced by 10 nM PTHrP (107-139). PTHrP (107-139), at 10 nM, also stimulated cytosolic VEGF immunostaining in hOB cells, and VEGF secretion into the medium conditioned by hOB or MG-63 cells for 24 h, which was (ng/mg protein): 10 ± 1 or 5 ± 3 (control), respectively, and 21 ± 1 or 11 ± 2 (PTHrP [107-139]-stimulated), respectively. Furthermore, medium conditioned by these cells for 24 h in the presence of 10 nM PTHrP (107-139), with or without 10 nM PTHrP (1-34), increased about 30% bovine aortic endothelial cell (BAEC) growth at 48 h. This effect was inhibited by adding a specific anti-VEGF antibody to the BAEC incubation medium. These findings demonstrate that the C-terminal domain of PTHrP induces expression and secretion of VEGF, a main angiogenic factor, in hOB cells and MG-63 cells. This relationship between PTHrP and VEGF has potential implications for both bone vascularization and bone formation, and neoangiogenesis in PTHrP-producing tumors.
High Prevalence of Low Bone Turnover and Occurrence of Osteomalacia after Kidney Transplantation
Authors: MONIER-FAUGERE MARIE-CLAUDE , MAWAD HANNA , QI QUANLE , FRIEDLER ROBERT M. , MALLUCHE HARTMUT H. 
Published: April 2021

Abstract.
Kidney transplantation corrects most of the metabolic abnormalities that cause renal osteodystrophy. However, many transplanted patients develop osteoporosis and other bone lesions that are related, at least in part, to their immunosuppressive regimen. The precise histologic patterns of bone disease after transplantation are not well defined. In a study designed to investigate this issue, 57 adult posttransplant patients agreed to undergo bone biopsies and blood drawings. There were 32 men and 25 women, mean age 45 ± 2 yr, who had received a kidney transplantation 5.6 ± 0.8 yr before biopsy. History of bone pain, fractures, and avascular necrosis was found in 22, 12, and 7 patients, respectively. Serum creatinine was 1.68 ± 0.1 mg/dl, 21% of patients were hypercalcemic, 63.2% had elevated parathyroid hormone (PTH) (>65 pg/ml), and 91.2% had normal calcitriol levels. Cancellous bone volume/tissue volume was below normal compared to age- and gender-matched control subjects in 56.1% of patients. Bone turnover (activation frequency) was low in 45.6%, normal in 28.1%, and elevated in 26.3% of patients. Bone formation rate/bone surface was low in 59.7%, normal in 35%, and elevated in 5.3% of the patients. Erosion surface/bone surface was high in 21.1% of patients. Mineralization was prolonged in 87.5% of patients, including 9 patients with osteomalacia and 12 patients with focal osteomalacia. Cumulative and maintenance doses of prednisone and time elapsed since transplantation correlated negatively with bone volume and bone turnover (r = -0.32 to -0.59, P < 0.05 to 0.01), whereas cumulative doses of cyclosporine or azathioprine, age, gender, or serum PTH levels did not. Regression analysis identified prednisone as the main factor responsible for low bone volume and bone turnover (r = 0.54 and r = 0.43, P < 0.01). No factors were found to predict delayed mineralization. The present study shows that low bone volume, low bone turnover, and generalized or focal osteomalacia are frequent histologic features in transplanted patients. The effects of age, gender, PTH, and cyclosporine on bone volume and bone turnover are apparently overridden by the prominent effects of glucocorticoids. The prevalence of mineralization defect in the presence of normal serum levels of calcidiol and calcitriol suggests vitamin D resistance and deserves further study.