bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chronic Oral Gabapentin Reduces Elements of Central Sensitization in Human Experimental Hyperalgesia
Authors: Gottrup Hanne , Juhl Gitte , Kristensen Anders D. , Lai Robert , Chizh Boris A. , Brown John , Bach Flemming W. , Jensen Troels S. 
Published: November 2004

Background
In chronic pain, increased activity from intact or damaged peripheral nerve endings results in an enhanced response in central pain transmission systems, a mechanism known as central sensitization. Central sensitization can also be invoked in human experimental models. Therefore, these models may be useful to characterize novel analgesics in humans. The anticonvulsant gabapentin has demonstrated efficacy in patients with neuropathic pain, but its mode of action remains unclear. This study examined the effects of gabapentin on signs of central sensitization (brush and pinprick hyperalgesia) in a human model of capsaicin-evoked pain, using a gabapentin dosing regimen similar to that used in the clinic. The aims were to determine whether gabapentin, dosed in a manner similar to that used in the clinic, affected the various components of central sensitization and to assess the utility of this model for characterizing novel analgesics.

Methods
Intradermal capsaicin (100 microg/20 microl) was administered in the volar forearm of 41 male human volunteers to induce pain and clinical signs of central sensitization. Gabapentin (titrated to 2,400 mg daily) or placebo was given orally for 15 days in a randomized, double-blind, parallel-group design. The capsaicin test was conducted at baseline and after gabapentin or placebo. Endpoints were the size of areas of brush-evoked allodynia (with cotton gauze) and pinprick hyperalgesia (with von Frey filament), and the intensity of ongoing brush- and pinprick-evoked pain.

Results
Gabapentin significantly reduced the area of brush allodynia compared with placebo (P </= 0.05) and insignificantly attenuated the area of pinprick hyperalgesia. Gabapentin had no significant effect on spontaneous and evoked pain intensity.

Conclusion
Oral gabapentin, administered to healthy volunteers in a regimen similar to that used in treating chronic neuropathic pain, reduces measures of central sensitization evoked by intradermal capsaicin. This suggests that the pain-relieving effect in chronic neuropathic pain condition is linked to the effect of gabapentin on central sensitization. The ability of the capsaicin model to detect the efficacy of this standard treatment of neuropathic pain suggests that it may have a predictive value for detection of efficacy in human subjects.
Effect of Pain and Audiovisual Stimulation on the Depression of Acute Hypoxic Ventilatory Response by Low-dose Halothane in Humans
Authors: Pandit Jaideep J. , Moreau Ben , Donoghue Simon , Robbins Peter A. 
Published: November 2004

Background
The effects of different low-dose volatile agents in blunting the acute hypoxic ventilatory response (AHVR) are variable. Arousal (due to audiovisual stimulation) may prevent isoflurane-induced blunting of AHVR. The purpose of this study was to assess whether this was also the case for halothane. The authors also assessed the effects of pain on the interaction of halothane and AHVR.

Methods
Step decreases in end-tidal partial pressure of oxygen using dynamic end-tidal forcing were performed from normoxia to hypoxia (50 mmHg) in 10 healthy volunteers, with end-tidal partial pressure of carbon dioxide held 1-2 mmHg above normal, in six protocols: (1) control conditions (darkened, quiet room, eyes closed) without halothane and (2) with 0.1 minimum alveolar concentration (MAC) halothane; (3) audiovisual stimulation (bright room, loud television) without halothane and (4) with 0.1 MAC halothane; (5) pain (electrical stimulation of skin over the tibia to produce a visual analog pain score of 5-6 out of 10) without halothane and (6) with 0.1 MAC halothane. The Bispectral Index of the electroencephalogram was also monitored.

Results
Halothane did not affect normoxic minute ventilation in any arousal state but significantly reduced the magnitude of AHVR by 50% regardless of the background arousal state (P < 0.001). Bispectral Index values were reduced by halothane only in the absence of arousal (P < 0.003). Both pain and audiovisual stimulation modestly increased normoxic minute ventilation (P < 0.002) and AHVR (P < 0.003).

Conclusions
Audiovisual stimulation does not prevent the blunting of AHVR by low-dose halothane. This result with halothane differs from previous results with isoflurane. Therefore, different anesthetics interact in different ways with arousal states. This finding raises the possibility that different anesthetics might differentially affect the hypoxic chemoreflex loop or that they might act in the brain at sites separate from the chemoreflex loop, differently to influence the wakefulness drive to ventilation.
DIATOM MINERALIZATION OF SILICIC ACID. VI. THE EFFECTS OF MICROTUBULE INHIBITORS ON SILICIC ACID METABOLISM IN NAVICULA SAPROPHILA1
Authors: Blank Gregory S. , Sullivan Cornelius W. 
Published: November 2004

ABSTRACTThe role of microtubules in silicon metabolism leading to valve formation was investigated in the pennate diatom Navicula saprophila Lange‐Bertalot & Bonik. By using synchronized cells blocked after mitosis and cytokinesis but prior to cell wall formation, effects due to inhibition of mitosis were eliminated. Cells were treated with three anti‐microtubule drugs to assess the role of microtubules. Chemical analogs to two of the drugs provided controls for inhibition not related to microtubule disruption. Although all three anti‐microtubule drugs reduced cell separation at high concentrations (1 × 10−3 M), podophyllotoxin was the only drug which reduced cell separation at concentrations lower than 1 × 10−5 M. None of the drugs at any concentration tested affected cell viability. There was no differential inhibitory effect between the active and inactive drugs on silicic acid transport, total uptake, incorporation, or pool formation. There was no qualitative difference between silica incorporated in treated and untreated cells. A colchicine binding component was isolated from N. saprophila. The characteristics of colchicine binding suggest this component may be tubulin. Microtubules do not appear to be involved in any of the steps of silicon metabolism leading to valve formation and yet they have profound influence on the symmetry and pattern of the mineralized product, the siliceous valve.
ATRACTOMORPHA ECHINATA GEN. ET SP. NOV., A NEW ANISOGAMOUS MEMBER OF THE SPHAEROPLEACEAE (CHLOROPHYCEAE)1,2
Authors: Hoffman Larry R. 
Published: November 2004

ABSTRACT Atractomorpha echinata gen. et sp. nov. is described from isolates derived from zygotes present in a dry soil sample obtained from Texas. The new genus is distinguished from Sphaeroplea primarily by its pattern of vegetative growth. While Sphaeroplea is distinctly filamentous with numerous coenocytic cells uniseriately arranged, Atractomorpha grows as individual, multinucleate, spindle‐shaped cells with sharply pointed extremities. Such cells may vary considerably in length (25–6000 μm, or more) and normally lack septa. In young, rapidly growing cultures the cells often attain lengths of 300–500 μm, but rarely exceed 1800 μm. The new species is further characterized by: (1) the regular formation of biflagellate zoospores in asexual reproduction, (2)anisogamy (occasionally oogamy) and (3) the size and ornamentation of its zygotes. Variations in vegetative morphology are discussed as are conditions for obtaining gametogenesis.
A PHYSIOLOGICAL TEST OF THE THEORY OF COMPLEMENTARY CHROMATIC ADAPTATION. I. COLOR MUTANTS OF A RED SEAWEED1
Authors: Ramus J. , van, der Meer John P. 
Published: November 2004

ABSTRACTThe physiological behavior of phycoerythrin‐deficient mutants of the red seaweed Gracilaria tikvahiae (Mc‐Lachlan 1979) is compared to that of their wild types. The mutants are phenotypically green while the wild types are red. Cloned scions were grown factorially at irradiances saturating and limiting to growth, and spectral distributions which were broadband (white) and narrowband (green). The green light field complements the absorptance spectrum of phycoerythrin. Experiments were performed in an outdoor continuous flow system. Physiological measurements included light‐harvesting pigment composition, instantaneous photosynthesis‐light relationships and growth. In all cases, the mutants performed as their wild type progenitors. Further, physiological responses occurring in no less than 8 days were dependent solely on irradiance (“intensity”), and were independent of spectral distribution (“color”). The data do not conform with the predictions of the theory of complementary chromatic adaptation for seaweeds.
EFFECTS OF EXTERNAL INORGANIC NITROGEN CONCENTRATION ON METABOLISM, GROWTH AND ACTIVITIES OF KEY CARBON AND NITROGEN ASSIMILATORY ENZYMES OF LAMINARIA SACCHARINA (PHAEOPHYCEAE) IN CULTURE1
Authors: Wheeler W. N. , Weidner M. 
Published: November 2004

ABSTRACTThe growth rate of Laminaria saccharina (L.) Lamour. is dependent on inorganic nitrogen in culture. Growth rates were saturated between 5 and 10 μmol · L−1 nitrate. The activities of ribulose‐1,5 bisphosphate carboxylase, phosphoenolpyruvate carboxykinase, mannitol‐1‐phosphate dehydrogenase, nitrate reductase and glutamine synthetase also varied with the concentration of inorganic nitrogen in the medium. All enzyme activities were lowest at 2.5 μmol · L−1 nitrate (the lowest concentration used) increasing to a maximum activity between 10 and 30 μmol · L−1 nitrate. Most enzyme activities followed a hyperbolic curve resembling those described by the Michaelis‐Menten equation, with different half‐saturation constants.
COMPOSITION OF SIEVE TUBE SAP FROM MACROCYSTIS PYRIFERA (PHAEOPHYTA) WITH EMPHASIS ON THE INORGANIC CONSTITUENTS1
Authors: Manley Steven L. 
Published: November 2004

ABSTRACTA quantitative accounting of the solids in the sieve tube sap from Macrocystis pyrifera (L.) e. Ag. was performed. The major organic compounds (mannitol, amino acids, and protein) and inorganic cations (K+, Na+, Mg2+ and Ca2+) were present near previously reported levels. The anions, until now unreported (except for iodide), included chloride as the major inorganic ion, bromide, phosphate, nitrate, and bicarbonate as the major inorganic carbon species. Sulfate and ammonium were below the detection limits of 1.5 ppm and 2 ppm, respectively. The elements B and As were also present although their speciation was not determined.
COMMUNITY STRUCTURE DYNAMICS OF EPILITHIC AND EPIPHYTIC DIATOMS IN A MISSISSIPPI STREAM1
Authors: O'Quinn Ruth , Sullivan Michael J. 
Published: November 2004

ABSTRACTEpilithic and epiphytic diatoms were collected monthly from 18 June 1979 through 19 May 1980 from both shaded and unshaded sites of Sessums Creek, a shallow, oligotrophic and strongly alkaline stream in northeastern Mississippi. The dominant macroalgae were filamentous green algae belonging to the non‐mucilage producing genera Cladophora and Rhizoclonium. Ninety taxa were identified with Navicula minima Grun. and Nitzschia dissipata (Kütz.) Grun. accounting for 50% of all valves counted. Other important taxa were Navicula menisculus var. upsaliensis (Grun.) Grun., N. cryptocephala var. veneta (Kütz.) Rabh., Achnanthes minutissima Kütz. and Cymbella turgida (Greg.) Cl. With few exceptions, the more dominant taxa were equally abundant in the shaded and unshaded sites and also in the epilithon and epiphyton. Species diversity (H') and the number of taxa in a sample in all four habitats showed an identical pattern, being lowest in winter and highest in fall. No one pair of habitats was more structurally similar than any‐other pair when compared by a similarity index (SIMI). Apparently, differences in light intensity and substrate type had little effect on diatom distribution in Sessums Creek and it was concluded that the locality sampled supported a single, nearly homogeneous diatom community.
A PHYSIOLOGICAL TEST OF THE THEORY OF COMPLEMENTARY CHROMATIC ADAPTATION. II. BROWN, GREEN AND RED SEAWEEDS1
Authors: Ramus J. 
Published: November 2004

ABSTRACTThe effect of light quantity (irradiance) on the photosynthetic physiology of seven seaweed species was distinguished from the effect of light quality (color). Plants were grown in outdoor, continuous‐flow tanks, at irradiances saturating and limiting to growth, and in spectral distributions that were either broadband (white) or narrowband (green). The green light field complemented the absorptance spectrum of phycoerythrin and approximated the spectral distribution of a submarine light field in turbid coastal water near the compensation depth. Physiological measurements, made after 6–15 days growth, included light‐harvesting pigment densities, instantaneous photosynthesis‐light relationships and growth rate. In all experiments, these photosynthetic properties were independent of spectral distribution (color) and in most experiments were dependent on irradiance. These data do not conform to the predictions of the theory of complementary chromatic adaptation for seaweeds.
PHYSIOLOGICAL CHANGES DURING GERMINATION OF PITHOPHORA OEDOGONIA (CHLOROPHYCEAE) AKINETES1
Authors: O'Neal Steven W. , Lembi Carole A. 
Published: November 2004

ABSTRACTAkinetes of Pithophora oedogonia (Mont.) Wittrock, formed in stationary phase cultures, were induced to germinate by transfer to fresh media. Changes in various physiological parameters were monitored during the first 20 d of germination. Ungerminated akinetes contained a greater percentage of lipid, starch, and dry matter and exhibited lower photosynthetic rates than did vegetative cells. Germination consisted of four phases. Phase I (day‐0 to day‐1) was marked by a rapid increase in respiratory rates. Phase II (day‐2 to day‐6) involved protrusion of the germination tube and was insensitive to cyanide, a respiratory inhibitor, and simazine, a photosynthetic inhibitor. Phase III (day‐7 to day‐14) was marked by rapid elongation of the germination tube, increasing photosynthetic rate, increasing chlorophyll and water content and declining levels of lipid and starch. Germination tube elongation during phase III was not inhibited by simazine, but was cyanide sensitive. Phase IV (day‐15 to day‐20) was characterized by a reduction in respiratory rate and an abrupt increase in the ratio of photosynthesis to respiration. Germination tube elongation during phase IV was inhibited by simazine. The data indicate that germination in Pithophora oedogonia akinetes consists of an extensive period (phases I, II and III) during which reserve materials are respired. Utilization of internal food reserves apparently permits akinetes to germinate and supports the initial growth of the germination tube in light limited microenvironments.
WALL MORPHOGENESIS INCOSCINODISCUS WAILESIIGRAN AND ANGST. I. VALVE MORPHOLOGY AND DEVELOPMENT OF ITS ARCHITECTURE1
Authors: Schmid Anna‐Maria M. , Volcani Benjamin E. 
Published: November 2004

ABSTRACTThe morphology of the valve ofCoscinodiscus wailesiiand the development of its siliceous architecture, studied in the SEM and TEM, is compared with valve formation inThalassiosira eccentrica(Ehrenberg.) Cleve. Though the areolae‐architecture of these two species differs in such that the cribrum is proximal and the foramen distal inT. eccentrica, and inC. wailesiithe cribrum is distal and the foramen proximal, the formation of their complex loculate system is similar, displacing a centrifugal growth pattern with respect to the valve, and a proximal to distal, sequentially. During base layer formation a hitherto undescribed rib system outlines the prospective areolae. The vertical differentiation is in principle the same as inT. eccentricaand also the cribra are formed centripetally in relation to the areolae in both species. The location of the cribra at the proximal or distal side, therefore, seems to be of minor importance for the sequence of silica deposition. Variation in girdle bands is discussed with respect to cell division. The prophasic nuclear migration from the interphase position to the girdle bands, where mitosis is performed, seems to be necessary for triggering the formation of the unilateral cleavage furrow that later forms a cleavage ring with excentric position. The divided nuclei migrate with the ingrowing cleavage furrow to the center of the newly created protoplasmic surfaces to initiate valve formation.
THE EFFECT OF NUTRIENT LIMITATION AND ITS INTERACTION WITH LIGHT UPON THE PRODUCTS OF PHOTOSYNTHESIS IN MERISMOPEDIA TENUISSIMA (CYANOPHYCEAE)1
Authors: Konopka Allan 
Published: November 2004

ABSTRACTThe metabolic fate of photosynthetically‐fixed CO2 was determined by labeling samples of Merismopedia tenuissima Lemmerman for 30 min with NaH14CO3 and analyzing its incorporation into low molecular weight compounds, polysaccharide and protein. In N‐ and P‐sufficient cultures, relative incorporation into protein increased as the irradiance used during the labeling period was decreased to 20 μE · m‐2 s‐1. This pattern was found for cells grown at irradiances of either 20 or 180 μE · m‐2· s‐1, although incorporation into protein was greater in cultures grown at the higher irradiance. In N‐limited continuous cultures, relative incorporation into protein was low, independent of growth rate, and the same for samples tested at 20 or 180 μE · m‐2· s‐1 irradiance. In contrast, 14C incorporation into protein by P‐limited cultures increased as growth rate increased, and at relative growth rates greater than 0.25, the incorporation was greater at 20 than at 180 μE · m‐2· s‐1. However, the total RNA content and maximum photosynthetic rate of the cultures was the same at all growth rates tested. The interaction between nutrient concentration and light intensity was studied by growing‐limited continuous cultures at the same dilution rate, but different irradiances. Relative incorporation into protein was highest in cultures grown at 20 μE · m‐2· s‐1, in which the relative growth rate was 0.4. These results suggest that photosynthetic carbon metabolism may respond to relative growth rate μ/μmax rather than to growth rate directly.
VARIABILITY IN RATIOS OF PHYTOPLANKTON CARBON AND RNA TO ATP AND CHLOROPHYLL A IN BATCH AND CONTINUOUS CULTURES1,2
Authors: Laws Edward A. , Karl David M. , Redalje Donald G. , Jurick Richard S. , Winn Christopher D. 
Published: November 2004

ABSTRACTThe feasibility of estimating phytoplankton carbon and RNA concentrations from measurements of ATP and chlorophyll a (chl a) concentrations was studied using chemostat populations of the marine diatom Thalassiosira weissflogii (Grunow) Fryxell & Hasle (= T. fluviatilis Hustedt). C:ATP and RNA:ATP ratios were studied for six additional marine species in batch culture representing five classes of phytoplankton. Statistical analyses revealed that both the growth rate and the factor limiting growth (NO3‐, NH4+, PO43‐ or light) could alter C:ATP, RNA: ATP, C:chl a and RNA:chl a ratios by amounts which were large compared to measurement error. An analysis of variance of the batch culture results indicated that both species and the source of inorganic nitrogen (NO3‐, or NH4+) had a significant effect on C:ATP and RNA:ATP ratios. Light had less of an influence on C:ATP and RNA:ATP ratios than on C:chl a and RNA:chl a ratios, and for this reason we feel that phytoplankton C and RNA concentrations can be estimated with greater reliability from ATP than from chl a measurements. The range of C:ATP and RNA:ATP values found for T. weissflogii under a variety of growth conditions was similar to that for the six additional species grown in batch culture, suggesting that this range of values is indicative of the extremes likely to occur in living cells. Our results and additional data in the literature indicate that phytoplankton C and RNA concentrations can be estimated to within a factor of two by multiplying ATP concentrations by 311 and 35, respectively, in N limited systems, and by 341 and 36, respectively in PO43‐ limited systems.
ELECTRON MICROSCOPIC OBSERVATIONS ON TUBULAR STRUCTURES INVOLVED IN CRYSTAL FORMATION IN THE RED ALGA PLEONOSPORIUM SQUARRULOSUM (HARV.) ABBOTT1
Authors: Kugrens Paul 
Published: November 2004

ABSTRACTHexagonal or angular crystalline inclusions in Pleonosporium (Naeg.) Hauck vegetative cells were examined using electron microscopy. Ultrastructural analysis reveals that the inclusions initially contain tubular elements resembling microtubules but, with continued differentiation, are transformed into rod containing crystals. The tubular structures initially measure 25 nm in diameter. Scattered tubules become arranged in a parallel and alternate pattern and undergo subsequent enlargement to approximately 29 nm. Following enlargement, each tubule apparently disaggregates into rods that form a crystal having hexagonally arranged rod‐like subunits. It is suggested that these tubules may represent microtubules and the resultant crystals are composed of tubulin.
GLOEOCOCCUS TETIMSPORUS SP. NOV. (TETRASPORALES, PALM ELL ACEAE), FROM COLORADO MOUNTAIN LAKES1
Authors: Kugrens Paul 
Published: November 2004

ABSTRACTA new species, Gloeococcus tetrasporus sp. nov., collected from mountain lakes, is described from unialgal culture. Vegetative cells are ellipsoid and Chlamydomo nas–like, occur in tetrad complexes within the general colonial matrix, and exhibit slow, limited motility within the confines of the individual gelatinous matrices. The colonial matrix is amorphous and structureless, without a definite bounding layer. Colonies may reach several centimeters in size. Vegetative cells have a parietal cup–shaped chloroplast with a central–basal pyrenoid and a small, linear stigma, two contractile vacuoles, and two short flagella. Cell division is by eleutheroschisis in nonflagellate cells. After two divisions, four daughter cells arc formed within the expanded parent wall that will become incorporated into the colonial matrix. Zoospores are formed either from transformed vegetative cells or after cytokinesis. Zoospore flagella are two to three times the length of vegetative cell flagella. Rapid flagellar movement ruptures the sheath and liberates the zoospores. When zoospores settle, they secrete new sheaths, and divide twice to initiate new colonies. Sexual reproduction and formation of resistant spores were not observed.