bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes in food quality of the green alga Scenedesmus induced by Daphnia infochemicals: biochemical composition and morphology
Authors: LÜRLING M. , DE LANGE H.J. , VAN DONK E. 
Published: November 2003

1. The effects of Daphnia infochemicals on the morphology and biochemical composition of Scenedesmus were studied and subsequently their influence on Daphnia life history. Three species of Scenedesmus (S. acutus, S. obliquus and S. subspicatus) were tested for Daphnia‐induced colony formation. Life history experiments were performed with Daphnia cucullata and D. magna feeding on unicellular or colonial S. acutus.2. Colony formation was promoted when S. acutus and S. obliquus were exposed to filtered water from a D. magna culture. S. subspicatus did not form colonies when exposed to culture water, but showed some colony formation when exposed to live D. magna.3. No clear differences were found in total lipid, protein or carbohydrate content between the unicellular and colonial ecomorphs of the three Scenedesmus species. However, fatty acid (FA) concentration and composition were changed. Total FA as a percentage of frozen dry weight (DW) were increased in colonies. The ratio of monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA) and the ratio of ω3 : ω6 fatty acids decreased in colonies.4. A short‐term grazing experiment with three size classes of Scenedesmus revealed lower clearance rates for small Daphnia when feeding on large colonial Scenedesmus.5. Life history parameters of both Daphnia species were influenced by food type. The intrinsic rate of population increase (r) was significantly lower for daphnids feeding on colonies.6. The negative influence of colonial Scenedesmus on population growth of Daphnia seems to be determined by algal morphology rather than biochemical composition.
Is the fatty acid composition of Daphnia galeata determined by the fatty acid composition of the ingested diet?
Authors: WEERS PAUL , SIEWERTSEN KLAAS , GULATI RAMESH 
Published: November 2003

1. The fatty acid (FA) composition of Daphnia galeata and their algal food was analysed and showed many similarities, however, some significant differences were also found in the relative abundance of the FA C16 : 4ω3 and docosahexaenoic acid (DHA). Their relative abundances were much lower in daphnids than in their algal diet.2. When daphnids were fed three distinct emulsion particles with DHA : eicosapentaenoic acid (EPA) ratios of c. 0.7, 2 and 4, the final DHA : EPA ratio in the daphnids always favoured EPA. The increase of the food DHA : EPA ratio resulted in a minor increase of DHA (to c. 2%). Feeding the animals on emulsion particles with increasing ratios of DHA : EPA, caused a minor (c. 2%) increase of DHA level but EPA levels remained high (c. 10%).3. When labelled with [14C]linoleic acid and [14C]linolenic acid daphnids showed low conversion of both essential FA into C20 polyunsaturated fatty acids (PUFAs). This low conversion activity might explain the importance of C20 PUFAs as dietary compounds in the food of Daphnia.4. The results indicate the insignificance of DHA and C16 : 4ω3 for daphnids. As EPA can be derived from C18 : 3ω3 it is not strictly essential, although it might be a significant factor in food quality for Daphnia.
Inter‐and intraspecific differences in fatty acid composition of freshwater crustacean zooplankton
Authors: SEKINO TATSUKI , NAKANISHI MASAMI , ISHIDA YASUYUKI , ISOMURA SHINICHI , TSUGE SHIN , OHTANI HAJIME , KIMOTO TAKASHI 
Published: November 2003

1. The composition of fatty acids (FA) from C14 to C18 was measured for edible seston and for individual Daphnia galeata, Diaphanosoma brachyurum and Eodiaptomus japonicus from Lake Biwa using a pyrolysis–gas chromatography (Py–GC) method. Based on the relative abundance of the FA, inter‐and intraspecific differences in composition were examined.2. Among the FA, C16 : 0 was the most abundant, both in the three zooplankton species and in edible seston smaller than 20 μm, suggesting that the composition of the zooplankton was roughly reflected by their diet. However, the abundance of C18 : 1 relative to C16 : 1 and C18 : 0 was much higher in each zooplankton species than in the diet.3. Comparison of the relative abundance of FA among the three zooplankton species revealed that intraspecific differences in FA composition are greater than interspecific differences. These results indicate that variability in FA composition is not necessarily species‐specific, and can be obscured by variation in composition between individuals.
Effects of cryoprotectant mixtures on physical properties of frozen and thawed puréed cooked potatoes: some introductory studies
Authors: Downey Gerard 
Published: November 2003

SummaryFreezing and thawing of cooked vegetables can have deleterious effects on the organoleptic and physical properties. In this study, the ability of mixtures of certain cryoprotectants to ameliorate these effects in cooked, frozen‐then‐thawed mashed potatoes was studied. Ingredients selected were hydrocolloids (xanthan, guar, carrageenan and pectin) and dairy proteins (sodium caseinate and whey protein concentrate). Ingredients were incorporated as mixtures of: (1) guar, pectin and whey protein concentrate; and (2) xanthan, carrageenan and sodium caseinate. Experimental design techniques were used to design the experiments and evaluate the results. Both ingredient mixtures significantly reduced maximum resistance to penetration and centrifugal drip loss. No practically significant effect of either treatment on purée colour was detected. Partial least squares regression models of changes in resistance to penetration with ingredient concentration produced goodness of fit (R2) and goodness of prediction (Q2) indices of 0.84 and 0.59 (mixture 1) and 0.76 and 0.51 (mixture 2), respectively. For drip loss, the corresponding values were 0.77 and 0.34 (mixture 1) and 0.77 and 0.44 (mixture 2), respectively. This approach may have potential for designing cooked potato purées with specified resistance to shear and drip loss values.
The Spo0A regulon of Bacillus subtilis
Authors: Molle Virginie , Fujita Masaya , Jensen Shane T. , Eichenberger Patrick , González‐Pastor José E. , Liu Jun S. , Losick Richard 
Published: November 2003

SummaryThe master regulator for entry into sporulation in Bacillus subtilis is the DNA‐binding protein Spo0A, which has been found to influence, directly or indirectly, the expression of over 500 genes during the early stages of development. To search on a genome‐wide basis for genes under the direct control of Spo0A, we used chromatin immunoprecipitation in combination with gene microarray analysis to identify regions of the chromosome at which an activated form of Spo0A binds in vivo. This information in combination with transcriptional profiling using gene microarrays, gel electrophoretic mobility shift assays, using the DNA‐binding domain of Spo0A, and bioinformatics enabled us to assign 103 genes to the Spo0A regulon in addition to 18 previously known members. Thus, in total, 121 genes, which are organized as 30 single‐gene units and 24 operons, are likely to be under the direct control of Spo0A. Forty of these genes are under the positive control of Spo0A, and 81 are under its negative control. Among newly identified members of the regulon with transcription that was stimulated by Spo0A are genes for metabolic enzymes and genes for efflux pumps. Among  members  with  transcription  that  was in‐hibited by Spo0A are genes encoding components of the DNA replication machinery and genes that govern flagellum biosynthesis and chemotaxis. Also in‐cluded in the regulon are many (25) genes with products that are direct or indirect regulators of gene transcription. Spo0A is a master regulator for sporulation, but many of its effects on the global pattern of gene transcription are likely to be mediated indirectly by regulatory genes under its control.
Lipoxygenase and cyclo‐oxygenase products in the control of regional kidney blood flow in rabbits
Authors: Oliver Jeremy J , Eppel Gabriela A , Rajapakse Niwanthi W , Evans Roger G 
Published: November 2003

Summary1. The aim of the present study was to examine the roles of cyclo‐oxygenase (COX)‐ and lipoxygenase (LOX)‐dependent arachidonate signalling cascades in the control of regional kidney blood flow.2. In pentobarbitone‐anaesthetized rabbits treated with NG‐nitro‐l‐arginine and glyceryl trinitrate to ‘clamp’ nitric oxide, we determined the effects of ibuprofen (a COX inhibitor) and esculetin (a LOX inhibitor) on resting systemic and renal haemodynamics and responses to renal arterial infusions of vasoconstrictors.3. Ibuprofen increased mean arterial pressure (14 ± 5%) and reduced medullary laser Doppler flux (MLDF; 26 ± 6%) when administered with esculetin. A similar pattern of responses was observed when ibuprofen was given alone, although the reduction in MLDF was not statistically significant. Esculetin tended to increase renal blood flow (RBF; 16 ± 7%) and MLDF (28 ± 13%) when given alone, but not when combined with ibuprofen.4. After vehicle, renal arterial infusions of noradrenaline, angiotensin II and endothelin‐1 reduced RBF and cortical laser Doppler flux (CLDF), but not MLDF. In contrast, renal arterial [Phe2,Ile3,Orn8]‐vasopressin reduced MLDF but not RBF or CLDF. Ibuprofen alone did not significantly affect these responses. Esculetin, when given alone, but not when combined with ibuprofen, enhanced noradrenaline‐induced renal vasoconstriction. In contrast, esculetin did not significantly affect responses to [Phe2,Ile3,Orn8]‐vasopressin, angiotensin II or endothelin‐1.5. We conclude that COX products contribute to the maintenance of arterial pressure and renal medullary perfusion under ‘nitric oxide clamp’ conditions, but not to renal haemodynamic responses to the vasoconstrictors we tested. Lipoxygenase products may blunt noradrenaline‐induced vasoconstriction, but our observations may, instead, reflect LOX‐independent effects of esculetin.
Effects of calcitriol on the immune system: new possibilities in the treatment of glomerulonephritis
Authors: Panichi Vincenzo , Migliori Massimiliano , Taccola Daniele , Consani Cristina , Giovannini Luca 
Published: November 2003

Summary1. 1,25‐Dihydroxyvitamin D3 (1,25(OH)2D3), the hormonal form of vitamin D, is widely appreciated to play a central role in calcium and phosphate homeostasis. However, it is becoming increasingly clear that the sterol also play an important role in the regulation of cellular growth, haematopoietic tissues and the immune system, as well as in the modulation of hormone secretion by several endocrine glands.2. In the present review, some of the mechanisms by which 1,25(OH)2D3 regulates immune function are highlighted. Moreover, a number of studies on the effects of calcitriol in several experimental animal models of renal disease are reported, suggesting new possibilities in the therapy of glomerulonephritis.
Oxidative metabolism of tamoxifen to Z‐4‐hydroxy‐tamoxifen by cytochrome P450 isoforms: An appraisal of in vitro studies
Authors: Coller JK 
Published: November 2003

Summary1. Tamoxifen is used for the prevention and treatment of oestrogen receptor‐positive breast cancer.2. Tamoxifen is metabolized extensively and the formation of Z‐4‐hydroxy‐tamoxifen (Z‐4‐OH‐tam), a potent anti‐oestrogen with high affinity for the oestrogen receptor, is believed to be strongly related to the therapeutic benefit achieved following tamoxifen treatment.3. In vitro studies using human liver microsome preparations have shown considerable interindividual variability in the formation rates of Z‐4‐OH‐tam.4. Cytochrome P450 (CYP) isoform‐specific chemical and monoclonal antibody inhibition studies have demonstrated that CYP2B6, CYP2C9, CYP2D6 and CYP3A4 all mediate the formation of Z‐4‐OH‐tam.5. Significant associations between the percentage inhibition of Z‐4‐OH‐tam by CYP isoform‐specific inhibitors and the rate of metabolism of CYP isoform‐specific index reactions and between individual expression of CYP2B6, CYP2C9 and CYP2D6 and Z‐4‐OH‐tam formation rates indicate predominant roles for these isoforms in this pathway.6. Genotyping of patients with regards to CYP2B6, CYP2C9 and CYP2D6 may play a role in prediction of Z‐4‐OH‐tam formation and, consequently, ultimate therapeutic benefit of tamoxifen treatment.
Clarithromycin reduces Isus and Ito currents in human atrial myocytes with minor repercussions on action potential duration
Authors: Gluais Pascale , Bastide Michèle , Grandmougin Daniel , Fayad Georges , Adamantidis Monique 
Published: November 2003

AbstractThe macrolide antibacterial agent clarithromycin has been shown to cause QT interval prolongation on the electrocardiogram. In rabbit heart preparations clarithromycin (concentration dependently) lengthened the action potential duration and blocked the delayed rectifier current. The aim of the present study was to investigate the clarithromycin effects: (i) on the Ca2+ L‐type and the main K+ repolarizing currents on human atrial myocytes, using whole‐cell patch clamp recordings and (ii) on action potentials recorded from human atrial and ventricular myocardium using conventional microelectrodes. It has been found that (i) 10–30 μm clarithromycin reduced the sustained current Isus significantly and that a 100 μm concentration was needed to cause a significant reduction in the transient outward current Ito, whereas clarithomycin did not affect the calcium current and (ii) clarithromycin (10–100 μm) prolonged the action potential duration in atrial preparations but did not alter the different parameters of the ventricular action potential. It is concluded that clarithromycin exerts direct cardiac electrophysiological effects that may contribute to pro‐arrythmic potential.
Reliability of Pharmacodynamic Analysis by Logistic Regression
Authors: Lu Wei , Ramsay James G. , Bailey James M. 
Published: November 2003

Background
Many pharmacologic studies record data as binary, yes-or-no, variables with analysis using logistic regression. In a previous study, it was shown that estimates of C50, the drug concentration associated with a 50% probability of drug effect, were unbiased, whereas estimates of gamma, the term describing the steepness of the concentration-effect relationship, were biased when sparse data were naively pooled for analysis. In this study, it was determined whether mixed-effects analysis improved the accuracy of parameter estimation.

Methods
Pharmacodynamic studies with binary, yes-or-no, responses were simulated and analyzed with NONMEM. The bias and coefficient of variation of C50 and gamma estimates were determined as a function of numbers of patients in the simulated study, the number of simulated data points per patient, and the "true" value of gamma. In addition, 100 sparse binary human data sets were generated from an evaluation of midazolam for postoperative sedation of adult patients undergoing cardiac surgery by random selection of a single data point (sedation score vs. midazolam plasma concentration) from each of the 30 patients in the study. C50 and gamma were estimated for each of these data sets by using NONMEM and were compared with the estimates from the complete data set of 656 observations.

Results
Estimates of C50 were unbiased, even for sparse data (one data point per patient) with coefficients of variation of 30-50%. Estimates of gamma were highly biased for sparse data for all values of gamma greater than 1, and the value of gamma was overestimated. Unbiased estimation of gamma required 10 data points per patient. The coefficient of variation of gamma estimates was greater than that of the C50 estimates. Clinical data for sedation with midazolam confirmed the simulation results, showing an overestimate of gamma with sparse data.

Conclusion
Although accurate estimations of C50 from sparse binary data are possible, estimates of gamma are biased. Data with 10 or more observations per patient is necessary for accurate estimations of gamma.
Mechanism of Pupillary Reflex Dilation in Awake Volunteers and in Organ Donors
Authors: Yang Laura L. , Niemann Claus U. , Larson Merlin D. 
Published: November 2003

Background
The mechanism of reflex pupillary dilation was investigated in eight patients who were declared brain dead after rupture of intracranial vascular malformations and in eight awake volunteers. The authors hypothesized that the reflex was primarily a spinal sympathetic reflex that would be blocked by topical application of the alpha1-adrenergic blocking agent dapiprazole and that it would be present in organ donors with intact spinal reflexes and no history of hypoxia.

Methods
In volunteers, pupil size was measured with an infrared pupillometer while brief painful electric stimuli were delivered to the finger. Pain was assessed with a visual analog scale and adjusted with each volunteer to equal 3 on a visual analog scale of 0-10. Subjects were studied before and after topical application of the alpha1-adrenergic antagonist dapiprazole. In organ donors, the authors measured pupil size after high-intensity tetanic electric stimulation and in dapiprazole-blocked and -unblocked pupils after surgically induced nociception.

Results
In volunteers, the pupil dilated 0.43 +/- 0.23 mm after nociceptive stimuli. Dapiprazole eyedrops blocked this dilation, confirming that the reflex in awake humans is primarily a sympathetic reflex. Baseline diameters were 5.7 +/- 0.5 mm before dapiprazole and 4.1 +/- 0.9 mm after dapiprazole. In organ donors, a tetanic electric current failed to dilate the pupil, whereas the skin incision dilated the pupil 0.4 +/- 0.4 mm, but this dilation was not blocked by dapiprazole.

Conclusion
The authors conclude that pupillary reflex dilation, as it is clinically performed in awake subjects by stimulating somatic nociceptors, is a sympathetic reflex. Because it is not present in organ donors, the neural pathway must require a supraspinal component for completion.
Halothane Enhances γ-Aminobutyric Acid Receptor Type A Function but Does Not Change Overall Inhibition in Inspiratory Premotor Neurons in a Decerebrate Dog Model
Authors: Stucke Astrid G. , Zuperku Edward J. , Tonkovic-Capin Viseslav , Krolo Mirko , Hopp Francis A. , Kampine John P. , Stuth Eckehard A. E. 
Published: November 2003

Background
Inspiratory premotor neurons in the caudal ventral medulla relay excitatory drive to phrenic and inspiratory intercostal motoneurons in the spinal cord. These neurons are subject to tonic gamma-aminobutyric acid type A (GABA(A))-mediated (GABA(A)ergic) inhibition. In a previous study, 1 minimum alveolar concentration (MAC) halothane depressed overall glutamatergic excitatory drive but did not change overall inhibitory drive to the neurons. This study investigated in further detail the effects of halothane on GABA(A)ergic inhibition by examining postsynaptic GABA(A) receptor activity in these neurons.

Methods
Studies were performed in decerebrate, vagotomized, paralyzed, and mechanically ventilated dogs during hypercapnic hyperoxia. The effect of 1 MAC halothane on extracellularly recorded neuronal activity was measured during localized picoejection of the GABA(A) receptor antagonist bicuculline and the GABA(A) agonist muscimol. Complete blockade of GABAergic inhibition by bicuculline allowed estimation of the prevailing overall inhibition of the neuron. The neuronal response to muscimol was used to assess the anesthetic effect on the postsynaptic GABA(A) receptor function.

Results
One minimum alveolar concentration halothane depressed the spontaneous activity of 19 inspiratory premotor neurons by 22.9 +/- 29.1% (mean +/- SD; P < 0.01). Overall excitatory drive was depressed 23.6 +/- 16.9% (P < 0.001). Overall GABAergic inhibition was not changed (+8.7 +/- 27.5%; P = 0.295), but the postsynaptic GABA(A) receptor function was increased by 110.3 +/- 97.5% (P < 0.001).

Conclusion
One minimum alveolar concentration halothane greatly enhanced GABA(A) receptor function on inspiratory premotor neurons but did not change overall synaptic inhibition, indicating that the presynaptic inhibitory input was reduced. Therefore, the anesthetic depression of spontaneous inspiratory premotor neuronal activity in the intact brainstem respiratory network is mainly due to a decrease in overall glutamatergic excitation.
Setting Mean Airway Pressure during High-frequency Oscillatory Ventilation According to the Static Pressure–Volume Curve in Surfactant-deficient Lung Injury
Authors: Luecke Thomas , Meinhardt Juergen P. , Herrmann Peter , Weisser Gerald , Pelosi Paolo , Quintel Michael 
Published: November 2003

Background
Numerous studies suggest setting positive end-expiratory pressure during conventional ventilation according to the static pressure-volume (P-V) curve, whereas data on how to adjust mean airway pressure (P(aw)) during high-frequency oscillatory ventilation (HFOV) are still scarce. The aims of the current study were to (1) examine the respiratory and hemodynamic effects of setting P(aw) during HFOV according to the static P-V curve, (2) assess the effect of increasing and decreasing P(aw) on slice volumes and aeration patterns at the lung apex and base using computed tomography, and (3) study the suitability of the P-V curve to set P(aw) by comparing computed tomography findings during HFOV with those obtained during recording of the static P-V curve at comparable pressures.

Methods
Saline lung lavage was performed in seven adult pigs. P-V curves were obtained with computed tomography scanning at each volume step at the lung apex and base. The lower inflection point (Pflex) was determined, and HFOV was started with P(aw) set at Pflex. The pigs were provided five 1-h cycles of HFOV. P(aw), first set at Pflex, was increased to 1.5 times Pflex (termed 1.5 Pflex(inc)) and 2 Pflex and decreased thereafter to 1.5 times Pflex and Pflex (termed 1.5 Pflex(dec) and Pflex(dec)). Hourly measurements of respiratory and hemodynamic variables as well as computed tomography scans at the apex and base were made.

Results
High-frequency oscillatory ventilation at a P(aw) of 1.5 Pflex(inc) reestablished preinjury arterial oxygen tension values. Further increase in P(aw) did not change oxygenation, but it decreased oxygen delivery as a result of decreased cardiac output. No differences in respiratory or hemodynamic variables were observed when comparing HFOV at corresponding P(aw) during increasing and decreasing P(aw). Variation in total slice lung volume (TLVs) was far less than expected from the static P-V curve. Overdistended lung volume was constant and less than 3% of TLVs. TLVs values during HFOV at Pflex, 1.5 Pflex(inc), and 2 Pflex were significantly greater than TLVs values at corresponding tracheal pressures on the inflation limb of the static P-V curve and located near the deflation limb. In contrast, TLVs values during HFOV at decreasing P(aw) (i.e., 1.5 Pflex(dec) and Pflex(dec)) were not significantly greater than corresponding TLV on the deflation limb of the static P-V curves. The marked hysteresis observed during static P-V curve recordings was absent during HFOV.

Conclusions
High-frequency oscillatory ventilation using P(aw) set according to a static P-V curve results in effective lung recruitment, and slice lung volumes during HFOV are equal to those from the deflation limb of the static P-V curve at equivalent pressures.