bluuebunny/crossref_metadata_2025 huggingface dataset:
Antarctic fish tissues preferentially catabolize monoenoic fatty acids
Authors: Sidell Bruce D. , Crockett Elizabeth L. , Driedzic William R.
Published: June 2005

Tissues of Antarctic marine fishes are very high in lipids, predominantly triacylglycerols (TAG). In addition to conferring static lift to these swimbladderless fishes, these rich lipid stores long have been considered as an important caloric resource to the animals. We have performed in vitro measurements of the rates of oxidation of 14C‐labeled carbohydrates and fatty acids by oxidative skeletal muscle and heart ventricle of an Antarctic teleost, Gobionotothen gibberifrons to assess the relative importance of these substrates to aerobic energy metabolism. Capacities for regeneration of ATP calculated from oxidation rates of these fuels clearly indicate that fatty acids are more effective substrates of energy metabolism than either glucose or lactate with both tissues. Substrate competition experiments conducted between the saturated fatty acid palmitate (16:0) and the monoenoic unsaturate oleate (18:1) comparing the oxidation rate of radiolabeled fatty acid in the presence and absence of unlabeled competitor demonstrate a clear preference of both tissue types for catabolism of the monounsaturated substrate. Measurements of maximal activity of the putative flux‐generating enzyme of mitochondrial β‐oxidation, carnitine palmitoyltransferase (CPT), with a variety of fatty acyl CoA esters also show significant preference for a monoenoic fatty acyl CoA, palmitoleoyl CoA (16:1). The general pattern of results suggests that monounsaturated fatty compounds are the most readily utilized substrates for energy metabolism by oxidation muscle tissues of this Antarctic species. © 1995 Wiley‐Liss, Inc.
Studies on the autolysis of m‐calpain from the skeletal muscle of the amphibian Rana ridibunda
Authors: Sargianos N. , Gaitanaki C. , Beis I.
Published: June 2005

The autolytic mechanisms responsible for the regulation of m‐calpain purified from the skeletal muscle of the amphibian Rana ridibunda were examined. Both subunits of the calpain molecule were found to undergo autolysis in the presence of Ca2+. Various divalent cations were examined for their ability to induce calpain autolysis. The concentrations of these cations required for the complete calpain autolysis were: 500 μM Ca2+, 2 mM Sr2+, 10 mM Ba2+, whereas Mg2+, even at 10 mM did not induce any autolysis. Calpain autolysis induced by the above divalent cations is a temperature dependent process. Presence of Mn2+or Sr2+reduces the Ca2+requirement of calpain for autolysis. The rate of autolysis depends on the protease concentration; protease inhibitors such as E‐64, leupeptin, antipain, and iodoacetic acid inhibit the autolysis of calpain; E‐64 inhibits irreversibly while leupeptin inhibits reversibly the autolysis; and irreversibly inactivated by E‐64 calpain is fully digested by native calpain. Autolysis of calpain in the presence of alkali denatured casein increase the Ca2+sensitivity of the protease for its half maximal and maximal caseinolytic activity. Limited autolysis of calpain is also induced in the presence of the endogenous substrate G‐actin, and the rate of autolysis is slower than that obtained in the absence of substrates. © 1995 Wiley‐Liss, Inc.
Factors influencing testosterone metabolism by anuran larvae
Authors: Hayes Tyrone B. , Licht Paul
Published: June 2005

The effects of experimental conditions—steroid concentration, temperature, treatment duration, tadpole density, and delivery mode—on testosterone (T) metabolic rates were examined in larval anurans. T uptake into tadpoles was measured by scintillation counting of [3H]T and metabolism of T was studied by thin layer chromatography in two anuran species, the African clawed frog (Xenopus laeuis) and the western toad (Bufo boreas). T was extensively metabolized by both species, but the effects of each experimental condition on T metabolism varied between species. In the study of delivery mode, tadpoles injected with T dissolved in saline metabolized T faster than animals in groups where the steroid was added directly to the water. Animals injected with T dissolved in oil metabolized T the slowest, but T was short‐lived in all cases. The current study demonstrates that concentration, temperature, treatment duration, tadpole density, and delivery mode may all affect steroid metabolic rates, but these effects vary between species in unpredictable ways. Since steroid metabolism may either activate or deactivate steroids, these factors are important in understanding the potency of steroids in tadpoles. A review of the literature dealing with steroid effects in anuran larvae illustrates these problems. © 1995 Wiley‐Liss, Inc.
Effects of unilateral cranial sympathectomy either alone or with sensory nerve sectioning on pedicle growth in red deer (Cervus elaphus)
Authors: Suttie James M. , Li Chunyi , Sheard Philip W. , Corson Ian D. , Waldrup Kenneth A.
Published: June 2005

In a previous study (Li et al., [1993], J. Exp. Zool., 267: 188–197) sensory nerve sectioning had no effect on the timing of pedicle growth. The aim of the present study was to determine whether sensory nerve sectioning in conjunction with sympathectomy would influence pedicle growth. Twelve intact male red deer claves were allocated to treatment before any pedicle growth as follows: 1) unilateral sensory nerve removal (USX, n = 5), 2) unilateral superior cervical ganglionectomy (SGX, n = 4), or 3) both USX and SGX (SG/USX, n = 3). The calves were observed weekly. In all cases the untreated side was the control. Pedicle initiation was measured with a pedicle detector and after initiation, growth was measured with a ruler. When the treated pedicles reached a length of 60 mm the calves were killed and tissues from the pedicle were examined immunohistochemically for nerves. No large bundles of nerves were observed in the treated pedicle although a few fine fibres were present. All calves grew pedicles. There were no significant differences in the timing of pedicle initiation either within treatment or between treatments. All denervated pedicles grew faster than controls and were consequently higher at examination. The fact that pedicle growth took place despite reduced innervation indicates that a continuous neural connection is not a pre‐requisite for normal pedicle growth. © 1995 Wiley‐Liss, Inc.
Sex reversal by testosterone and not by estradiol or temperature in Calotes versicolor, the lizard lacking sex chromosomes
Authors: Ganesh Subramaniam , Raman Rajiva
Published: June 2005

The garden lizard Calotes versicolor lacks identifiable sex chromosomes. The present study demonstrates that temperature has no apparent effect on the determination of sex. In embryos reared at higher temperature (32°, 34°, 35°C), the gonads differentiate earlier than in controls and the overall duration of embryonic incubation is dramatically reduced. Exogenous administration of testosterone (100 μg/egg) to embryos of stages 28, 30, and 33 results in the majority of them developing into males; no female is encountered. Testosterone also accelerates the differentiation of testes. Estradiol (5, 10, μg/egg), administered at the same stages as testosterone, does not show any effects on gonadal differentiation. These results indicate that in C. versicolor, female is the default sex and the male is heterogametic. Apparently, this is the first report in a reptile in which testosterone has been shown to cause reversal into male sex. © 1995 Wiley‐Liss, Inc.
Oocyte and zygote zona pellucida permeability to macromolecules
Authors: Legge Michael
Published: June 2005

Zona pellucida intact mouse pre‐and post‐ovulatory oocytes and zygotes were investigated for permeability to macromolecules using graded neutral fluorescein isothiocyanate (FITC) dextrans (molecular weight range 3.84–170 kDa) and a range of galactose‐binding lectins (molecular weight range 40–247 kDa). The use of both FITC neutral dextrans and FITC galactose‐binding lectins gave good agreement in the zona pellucida permeability studies. Zona pellucida intact pre‐and post‐ovulatory oocytes were permeable to both markers up to a molecular weight range of 170 kDa although movement across the zona pellucida was diminished between 100 to 150 kDa with no detectable permeability at molecular weight range of 170 kDa. Zygotes demonstrated a decreased zona pellucida permeability at around 110 kDa. Two galactose‐containing oligosaccharide‐rich zones in the zona pellucida were identified, and changes in zygote vitelline membrane galactose‐binding lectin affinity were detected. © 1995 Wiley‐Liss, Inc.
Bone regrowth in young mice stimulated by nail organ
Authors: Zhao Weiguang , Neufeld Daniel A.
Published: June 2005

Recent studies of postamputational repair following digit‐tip amputation revealed am unexpected correlation between nail regrowth and bone regrowth in mice. To examine putative effects of nail on bone regrowth, phalangeal tips were amputated such that nail was artificially removed from distal levels or retained following proximal level amputations. In the absence of nail, bone did not regrow at distal levels. Conversely, when nail was surgically retained bone regrew form proximal levels. The nail organ profoundly influences bone regrowth. © 1995 Wiley‐Liss, Inc.
Androstenedione metabolism in the indifferent stage of bovine gonad development
Authors: Juárez‐Oropeza M. A. , López V. , Álvarez‐Fernández G. , Gómez Y. , Pedernera E.
Published: June 2005

Suspensions of cells obtained from genital ridges and gonads of bovine embryos of 1.0‐3.4 cm in crown‐rump (C‐R) length were used for studies of the metabolism of radiolabeled exogenous steroid precursor. Tritiated androstenedione was employed as precursor and the final products of their metabolism were evaluated after separation by thin‐layer chromatography. Genetic sex was determined by the karyotype of hepatocytes from the same embryos. The extent of conversion of tritiated androstenedione was higher in cells from male embryos than cells from female embryos. Furthermore, androstenedione was metabolized mainly to testosterone in male embryos. By contrast, cells obtained from female embryos transformed androstenedione to estrone and 17β‐estradiol. The onset of this activity was observed at 1.8 cm in C‐R length in males and at 2. 2 cm in C‐R length in females. In all cases, after the onset, the metabolic activity increased in relation to the age of the embryos. These data show that in the bovine embryo gonad, the activity of aromatase and 17β‐hydroxysteroid dehydrogenase are present when the morphological differentiation of the gonadal sex has not yet been established. © 1995 Wiley‐Liss, Inc.
Mode of action of the neurotransmitter 5‐hydroxytryptamine in stimulating ovarian maturation in the red swamp crayfish, Procambarus clarkii: An in vivo and in vitro study
Authors: Sarojini Rachakonda , Nagabhushanam Rachakonda , Fingerman Milton
Published: June 2005

Ovarian explants from the red swamp crayfish, Procambarus clarkii, were incubated with 5‐hydroxytryptamine (5‐HT) and muscle, and with 5‐HT in combination with eyestalk tissue, brains, or thoracic ganglia. In vitro, 5‐HT without brain or thoracic ganglia in the incubation medium had no significant effect on the ovarian explants. In contrast, in vitro brains and thoracic ganglia induced ovarian maturation, indicating the presence of a gonad‐stimulating hormone (GSH) in these tissues. However, this in vitro stimulatory effect was significantly greater when 5‐HT was present in the incubation medium with the brains and thoracic ganglia. These results provide in vitro evidence in support of the hypothesis that the previously observed in vivo stimulatory action of 5‐HT on the ovaries is an indirect one, 5‐HT acting to stimulate release of a GSH. © 1995 Wiley‐Liss, Inc.
Modulation of avian responsiveness to chemical irritants: Effects of prostaglandin E1 and analgesics
Authors: Clark Larry
Published: June 2005

Chemical irritation appears to be modulated by similar mechanisms in birds and mammals, despite an apparent difference between the two taxa for what constitutes a chemical irritant. Prostaglandin E1, a well‐described mammalian pain modulating substance, was not itself aversive to starlings, although it did sensitize birds to the effects of the avian irritant oaminoacetophenone. Aspirin and aspirin‐like drugs tended to desensitize starlings to the aversive effects of acetophenone bird repellents. Because the modulation mechanisms for the perception of pain appear to be similar in birds and mammals, the taxonomic differences in the perception of stimuli as irritating is inferred to be due to differences in receptor mechanism. The differences in sensory perception of chemical irritants has important implications for vertebrate foraging ecology and the evolution of plant‐animal interactions. © 1995 Wiley‐Liss, Inc.

This article is a US Government work and, as such, is in the public domain in the United States of America

.
Purification of a 240 kDa protein from serum and follicular fluid of water buffalo and its identification as haptoglobin
Authors: Bergamo P. , Balestrieri M. , Carratore V. , Abrescia P.
Published: June 2005

The fluids from healthy growing follicles of water buffalo were previously found free of the polypeptides H (Mr 36,000) and L (Mr 21,000) which were instead detected in fluids from atretic follicles and blood. Here we report evidence that these two polypeptides, as selected from serum by specific anti‐L antibodies, are the subunits of an oligomeric protein. The protein was purified from serum or follicular fluid, and its molecular weight (240 kDa), isoelectric point (6. 5), and amino acid composition were determined. The NH2‐terminal sequences of the subunits L and H were analyzed: 100% and 90% homology with α and β chains of bovine haptoglobin, respectively, was found. Thus, haptoglobin can be used as a novel molecular marker to assess the physiological state of the blood‐follicle barrier or discriminate between atretic and healthy follicles. © 1995 Wiley‐Liss, Inc.
Maternal transfer of estradiol to egg yolks alters sexual differentiation of avian offspring
Authors: Adkins‐Regan Elizabeth , Ottinger Mary Ann , Park Jeanne
Published: June 2005

Three experiments were conducted to determine whether avian egg yolks contain the sex steroid 17β‐estradiol and whether experimentally produced elevations in maternal estradiol alter yolk estradiol and influence sexual differentiation of the offspring. The yolks of eggs laid by Japanese quail (Coturnix japonica) were found to contain significant amounts of estradiol comparable to those in the maternal circulation. Treatment of laying females with estradiol benzoate (EB) resulted in elevated yolk estradiol and a permanent morphological alteration of female off‐spring in the form of an increased incidence of right oviducts in adulthood. Such maternal transfer of a sex steroid to the egg yolk constitute a potentially significant source of maternal influence over embryonic development and adult phenotype in oviparous species. © 1995 Wiley‐Liss, Inc.
Neuronal localization and evoked release of norepinephrine in the cnidarian Renilla koellikeri
Authors: Pani Amar K. , Anctil Michel , Umbriaco Denis
Published: June 2005

Neuronal release of norepinephrine (NE) in the sea pansy Renilla koellikeri was investigated by searching for evidence 1) of neuronal localization of endogenous NE and 2) of synaptic‐like release of exogenously supplied NE in sea pansy tissues. Measurements of endogenous NE by high‐performance liquid chromatography with electrochemical detection corresponded with the visualization of specific NE immunoreactivity in six individual colonies thus sampled. Peroxidase‐antiperoxidase immunohistochemistry with antisera against NE‐aldehyde‐protein conjugates revealed that cellular NE immunostaining was predominantly associated with neurons and amoebocytes constituting the mesogleal nerve net. Transient increases of tritium outflow above background levels were evoked by field electrical stimulation of colonial (rachis) tissues pre‐loaded with 1 μM [3H]NE, under conditions that elicited nerve net‐mediated bioluminescence. This evoked release was largely reduced or abolished in a reversible manner by substituting high‐magnesium or calcium‐free seawater to normal seawater perfusate. Evoked release was significantly enhanced by exogenous norepinephrine (50 μM) and reduced in half or less by the α‐adrenergic blockers phentolamine and yohimbine (10 μM), thus providing support for the existence of an autoregulatory mechanism associated with release. These results suggest that neuronal, synaptic‐like release of NE occurs in the nerve‐net of the sea pansy, a representative of the phylum (Cnidaria) in which the first nervous systems of multicellular organisms are believed to have originated. © 1995 Wiley‐Liss, Inc.
Isolation and characterization of the cDNA encoding the spiny dogfish shark (Squalus acanthias) form of cytochrome P450c17
Authors: Trant John M.
Published: June 2005

Cytochrome P450c17 is a key steroidogenic enzyme for the production of sex steroids in gonadal tissue and for cortisol production in adrenal tissue. This protein possesses two enzymatic activities. The 17α‐hydroxylase activity results in the introduction of a hydroxyl group at the 17α‐position. The resultant 17α‐hydroxylated, C21 pregnene is converted to a C19 andro‐gen by the C17,20‐lyase activity. A cDNA library was constructed from poly(A)‐enriched mRNA isolated from spiny dogfish shark (Squalus acanthias) testis and ligated into EcoRI‐cut lambda arms. The amplified library was screened using a bovine P450c17 cDNA probe and five positive clones were isolated. The described cDNA encompasses 23 bp of the 5′‐untranslated region, a 1,527 bp open reading frame, and 414 bp of the 3′‐untranslated region. A putative polyadenylation signal (AATAAA) is 18 bp from the poly(A) tail. Northern blot analysis showed a single transcript of 1.9 kb, thus indicating the isolated clone is a full‐length cDNA. The deduced amino acid sequence of the shark form of P450c17 is 59% and 57% identical to the rainbow trout and chicken forms, respectively. The shark form is 43% to 46% identical to mammalian forms (rat, human, mouse, bovine, and porcine). There are large regions of extremely high identity shared among all the forms. The deduced shark 17α‐hydroxylase protein is 509 residues in length with a predicted weight of 57.2 kDa. Non‐steroidogenic COS cells, transfected with the shark P450c17 cDNA, was capable of 17α‐hydroxylase and C17,20‐lyase activities using both pregnenolone and progesterone as initial substrates. © 1995 Wiley‐Liss, Inc.
In situ detection of gonadotropin‐releasing hormone (GnRH) receptor mRNA expression in the rat ovarian follicles
Authors: Kogo Hiroshi , Kudo Akihiko , Park Min Kyun , Mori Takao , Kawashima Seiichiro
Published: June 2005

To clarify the target cells of GnRH in the ovary, in vivo expression of ovarian GnRH receptor mRNA was examined histologically by in situ hybridization in immature rats treated with PMSG only or in combination with hCG. Strong hybridization signals were observed in the granulosa cells of atretic follicles. However, no significant signals were found in the granulosa cells of healthy small, preantral, or early antral follicles. Healthy Graafian and preovulatory follicles also showed intense signals in their mural granulosa cells, but no signals were detected in the cumulus oophorus cells. Corpora lutea showed only weak signals, but luteinizing follicles probably after atresia exhibited signals of moderate intensity in their luteinized and remaining granulosa cells. No signals were detected in the theca cells and oocytes in all the follicles. Interstitial cells sometimes exhibited hybridization signals of moderate intensity, when the cells were eosinophilic. Pretreatment with different combinations of gonadotropins yielded different ovarian histology, but this had no influence on the localization of hybridization signals. These results, showing that the authentic GnRH receptor mRNA was expressed in a certain cell population in the rat ovary, suggest that the receptor is involved in the control of various ovarian functions including follicular development, atresia, ovulation, and luteinization after ovulation and follicular atresia. © 1995 Wiley‐Liss, Inc.
Analysis of ciliary beat frequencies in hamster oviducal explants
Authors: Di Carlantonio G. , Shaoulian R. , Knoll M. , Magers T. , Talbot P.
Published: June 2005

We have developed a simple direct method, requiring minimal manipulation, to measure beat frequencies of the cilia on the external surface of hamster oviducal infundibula in vitro. Two perfusion chambers (closed and open) were used; both can be hand‐made in a few minutes and discarded after use. Ciliary beat frequencies were determined by measuring variations in light intensity with time in a single pixel positioned over a video image of the beating cilia. Data files were collected using Image 1 software and later transferred to PSI Plot or Lotus 123 spreadsheets for analysis by counting the number of brightness peaks recorded per second or by subjecting the data to Fourier transformation with or without smoothing. These methods of analysis gave similar results. To verify that Image 1 data files contain accurate representations of CBF, videotapes of beating cilia were made and subjected to frame‐by‐frame analysis. Image 1 interfaced with a standard video camera was found to collect reliable data over a beat frequency range of 0‐‐15 cycles/sec. In some Fourier transforms, secondary peaks were observed and were shown to represent cilia beating at more than one frequency in a sampled region. Coefficients of variation for repeated measurements taken on the same region varied from 4.1% to 9.0%. Small but significant differences were found between beat frequencies at different regions of the same oviduct. When chambers were perfused discontinuously and measurements of beat frequency were made at least 5 min after each perfusion, no effect of perfusion on frequencies was observed. However, during continual perfusion of the open chamber, a slight but significant increase in beat frequency was observed after perfusion was initiated. Muscle contraction, which sometimes occurs in the open chamber, did not affect beat frequency measurements. Infundibula could be stored at 4°C overnight without any negative effect on beat frequencies. Cold storage also reduced muscle contraction. Placement of a small coverslip on infundibula in the open chambers was also found to reduce muscle contraction and facilitate beat frequency measurements. Coverslipping did not affect beat frequencies. This method of beat frequency analysis will be valuable for analyzing factors that regulate or influence cilia in mammalian oviducts. © 1995 Wiley‐Liss, Inc.
On the c‐mos proto‐oncogene product during meiotic maturation in bovine oocytes cultured in vitro
Authors: Tatemoto Hideki , Terada Takato
Published: June 2005

The present study was carried out using dot‐blot Western analysis with pp39mos‐specific polyclonal antibodies to examine the quantitative and qualitative changes of c‐mos proto‐oncogene product, Mos, during bovine oocyte maturation in vitro. Mos is present throughout meiotic maturation, is produced from around the onset of meiotic resumption, and is phosphorylated on germinal vesicle breakdown. These results indicate for the first time that the synthesis and phosphorylation of Mos during maturation culture play a key role in the accomplishment of meiosis in bovine oocytes. © 1995 Wiley‐Liss, Inc.
Laterality of aggressive responses in Anolis
Authors: Deckel A. Wallace
Published: June 2005

This experiment examined whether or not aggression in the lizard Anolis (suborder Lacertilia, family Iguanidae) is lateralized. Five pair of adult Anolis were subjected to several 20 min behavioral trials, during which one animal was placed in the cage of the other. Behaviors were captured on video and coded according to eye preference, motor activity, posture, and color. Analysis of the data found that the most aggressive behaviors, including biting, threatened biting, and aggressive movements, were done under the guidance of the left eye. Both left and right eyes were used with equal frequency during non‐aggressive movements. Most of these aggressive episodes were done while the animals were “lightly” colored. Because of an almost complete crossing‐over of the optic tract in Anolis, along with the absence of a corpus callosum, it is likely that most, if not all, of the information in the left eye was processed by the right hemisphere. These results suggest that the lizard Anolis, like humans, rats, and chicks, may mediate aggressive responses predominantly through right‐hemispheric brain mechanisms. © 1995 Wiley‐Liss, Inc.
Purification and properties of two malic enzyme activities in liver mitochondria of Squalus acanthias (spiny dogfish)
Authors: Zhou Xiaoqin , Korte Joseph J. , Anderson Paul M.
Published: June 2005

Two malic enzymes are present in liver mitochondria from Squalus acanthias (spiny dogfish), an NAD(P)‐dependent and an NADP‐dependent malic enzyme. The NAD(P)‐dependent enzyme was partially purified and found to have kinetic properties similar to other malic enzymes; the molecular weight is ≈ 130,000. The maximal rate with NADP is 40% of the maximal rate with NAD. The NADP‐dependent malic enzyme was purified to homogeneity and also has properties similar to other malic enzymes, including a subunit molecular weight of ≈ 61,000 and a native molecular weight of ≈ 250,000; however, the rate as a function of malate concentration is described by a sigmoid curve. Both enzymes require either Mn2+ or Mg2+ for activity, are activated by fumarate or succinate, and are inhibited by ATP. Both enzymes are inhibited by low concentrations of oxalacetate; the Ki for competitive inhibition of the NAD(P)‐dependent malic enzyme by oxalacetate is 4 μM. The Km for Mn2+ is considerably lower than the Km for Mg2+ for both enzymes; the maximal rate with Mg2+ is about the same as with Mn2+ for the NADP‐dependent enzyme, but only 20% of that with Mn2+ for the NAD(P)‐dependent enzyme. The possible role of these enzymes in contributing to citrate synthesis by isolated spiny dogfish liver mitochondria is discussed. NAD‐ or NADP‐dependent malic enzyme activity could not be detected in the cytosol. © 1995 Wiley‐Liss, Inc.
Freezing of zona‐free mouse embryos: Characteristics of the plasma membrane and subsequent development of the embryos
Authors: Martí M. , Nogués C. , Egozcue J. , Ponsà M.
Published: June 2005

Frozen‐thawed mouse embryos with (+ZP) and without (−ZP) zona pellucida have been studied at the Scanning Electron Microscope (SEM) to determine how the process affects the plasma membrane and the subsequent embryo development. The main difference observed in −ZP embryos immediately after thawing is the abnormal morphology and distribution of microvilli. This could explain the spontaneous separation of blastomeres in ‐ZP embryos, and the decrease in their survival rate. If thawed −ZP embryos are allowed to recover in culture, their plasma membrane characteristics and survival rate are identical to those of control embryos. © 1995 Wiley‐Liss, Inc.
Water drinking in snakes: Evidence for an esophageal sphincter
Authors: Bels Vincent L. , Kardong Kenneth V.
Published: June 2005

Drinking fluids by snakes, as in many amniotes, requires elevation of water from the substrate into the mouth, then passage through the pharynx into the esophagus. A model of oral transport of fluids in snakes, the buccal‐pump mechanism, predicts that snakes possess a functional sphincter guarding retrograde flow of accumulating fluid from the esophagus, and that intraoral transport proceeds sequentially under active pressure generation by the buccal‐pump mechanism. Cineradiographic images and kinematic profiles of fluid transport were analyzed to test these predictions. Our results confirm the following: 1) the presence of a temporary esophageal sphincter, which prevents retrograde passage of fluid from the esophagus back into the mouth. 2) During each rhythmic drinking cycle, positive and negative pressure surges generated by the oropharyngeal cavity first aspirate fluid into the mouth then drive it intraorally, past the esophageal sphincter, and into the esophagus where each pulse of fluid contributes to a growing reservoir of water. 3) The oropharyngeal cavity is functionally divided into anterior and posterior tandem chambers that pump fluid sequentially from one (anterior) to the other (posterior), which then empties into the esophagus. 4) In large snakes, capillarity is not a significant force contributing to intraoral transport of water. These findings support the proposed buccal‐pump models of fluid drinking by snakes. © 1995 Wiley‐Liss, Inc.
Fibroblast growth factor‐2 immunoreactivity is present in the central and peripheral auditory pathways of adult rats
Authors: Silva Vivian Alessandra , Gomide Vânia Canterucci , Chadi Gerson
Published: June 2005

Recent findings have pointed out the role of neurotrophic factors in the survival and maintenance of neurons of the auditory system. Basic fibroblast growth factor (bFGF, FGF‐2) is a potent neurotrophic molecule whose actions can be seen in the central and peripheral nervous systems. In the present study, FGF‐2 immunoreactivity was analyzed in the auditory pathways of the adult rat, employing a well‐characterized polyclonal antibody against FGF‐2. In the cochlea, FGF‐2 immunoreactivity was observed in the inner and outer hair cells of the organ of Corti, spiral ganglion neurons, spiral limbus, and stria vascularis. Stereological methods employing optical fractionator revealed the presence of 84.5, 15, and 0.5% of spiral ganglion neurons possessing FGF‐2 immunoreactivity of strong, moderate, and weak intensity, respectively. In the central auditory pathways, FGF‐2 immunoreactivity was found in the cytoplasm of the neurons of the cochlear nuclei, trapezoid body nuclei, medial geniculate nucleus, and inferior colliculus. The two‐color immunoperoxidase method showed FGF‐2 immunoreactivity in the nuclei of astrocytes throughout the central auditory pathway. Computer‐assisted microdensitometric image analysis revealed higher levels of specific mean gray values of FGF‐2 immunoreactivity in the trapezoid body and ventral cochlear nucleus and also in the spiral ganglion and inner hair cells. Sections incubated with FGF‐2 antibody preabsorbed with human recombinant FGF‐2 showed no immunoreaction in the majority of the studied regions, exhibiting only a slight immunoreactive product in the hair cells of the organ of Corti. Furthermore, no changes in immunoreactivity were observed in sections incubated with FGF‐2 antiserum preincubated with human recombinant acidic FGF (FGF‐1). The findings suggest that FGF‐2 may exert paracrine and autocrine actions on neurons of the central and peripheral auditory systems and may be of importance in the mechanism of hearing diseases. J. Morphol. © 2005 Wiley‐Liss, Inc.
Interpretation of butyltin mass spectra using isotope pattern reconstruction for the accurate measurement of isotope ratios from molecular clusters
Authors: Meija Juris , Centineo Giuseppe , Ignacio Garcia Alonso J. , Sanz‐Medel Alfredo , Caruso Joseph A.
Published: June 2005

The fragmentation patterns of butyltin compounds (mono‐, di‐, and tributyltin) in an electron impact ion source were studied using an isotope pattern reconstruction algorithm with emphasis on isotope ratio measurements from molecular clusters. For this purpose, standards of natural tin isotope abundance and a 119Sn‐enriched mixture of the three compounds were both ethylated and propylated using sodium tetraalkylborates. The corresponding mass spectra of the various tetraalkyltin compounds prepared were obtained by GC/MS after their extraction with hexane.

The results showed that pure interference‐free molecular clusters were obtained only for certain R3Sn+ ions where no isobaric overlap with R2SnH+ ions occurred (e.g. BuEt2Sn+ overlaps with Bu2SnH+). These ions are ideal candidates for accurate Sn isotope ratio measurements, while isotope pattern perturbing interferences are observed for other molecular fragments down to Sn•+. Isotope pattern reconstruction algorithm thus can be used as an analytical tool to ensure the absence of molecular interferences—a requirement for accurate isotope ratio measurements from molecular clusters. The relevance of these studies for the determination of butyltin compounds in environmental samples by isotope dilution GC/MS is also discussed. Copyright © 2005 John Wiley & Sons, Ltd.
New Enantiomeric Polylactide‐block‐Poly(butylene succinate)‐block‐Polylactides: Syntheses, Characterization and in situ Self‐Assembly
Authors: Jia Lin , Yin Lingzhi , Li Yang , Li Qiaobo , Yang Jing , Yu Jianyong , Shi Zhen , Fang Qiang , Cao Amin
Published: June 2005

Summary: In situ self‐assemblies of new biodegradable triblock PLLA‐b‐PBS‐b‐PLLA and PDLA‐b‐PBS‐b‐PDLA have been investigated in acetonitrile solution. At first, two series of PLLA‐b‐PBS‐b‐PLLA and PDLA‐b‐PBS‐b‐PDLA, respectively denoted as the P and Q triblock copolyester series, were prepared with fixed PBS block ($\overline M _{{\rm n},{\rm NMR}}$ = 6.9 kDa) and diverse enantiomeric PLLA/PDLA blocks. Further, their chemical structures and thermal properties were characterized by means of titration, nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC), polarimeter, wide‐angle X‐ray diffraction (WAXD) and thermal analytical instruments. When mixing the synthesized enantiomeric copolyester pairs denoted as P1/Q1 – P8/Q8 in acetonitrile solution at 60 °C, in situ self‐assemblies were found to happen for the P4/Q4 to P8/Q8 pairs, bearing longer enantiomeric PLA block lengths. DSC and WAXD analysis of the self‐assembled microparticles demonstrated that PLLA/PDLA racemic crystals were formed for the P5/Q5 – P8/Q8 systems, as evidenced by their melting points over 200 °C, and a new X‐ray diffraction peak detected at 2θ = 11.8°. Moreover, morphological studies by scanning electron microscopy (SEM) indicated the formation of disk‐ or platelet‐like microparticles. It was noted that the diameters of the microparticles self‐assembled in situ decreased from 1.28–1.50 μm down to 480–660 nm, through tailoring the enantiomeric PLA block length. Other factors, such as a central PBS block, the enantiomeric block length and the preparation conditions were suggested to play important roles in the in situ self‐assembly of these enantiomeric triblock copolyesters. These results provide a facile way to self‐assemble hydrophobic, biodegradable microparticles, through tuning the important van der Waals stereocomplexation interactions between two enantiomeric blocks in solution.

In situ self‐organisation of new PLLA‐b‐PBS‐b‐PLLA and PDLA‐b‐PBS‐b‐PDLA triblock copolyester pairs in dilute solution.

magnified image

In situ self‐organisation of new PLLA‐b‐PBS‐b‐PLLA and PDLA‐b‐PBS‐b‐PDLA triblock copolyester pairs in dilute solution.
Synthesis of and Structural Studies on Repeating Sequences of Abductin
Authors: Bochicchio Brigida , Jimenez‐Oronoz Felipe , Pepe Antonietta , Blanco Mario , Sandberg Lawrence B. , Tamburro Antonio M.
Published: June 2005

Summary:Little data exist on the structure and function of compressible elastomeric proteins such as abductin. An understanding of the underlying structural features of these proteins may lead to the development of a new class of highly tailored “compressible” hydrogels. To that effect, in this work, the structure of abductin was investigated by means of studies on several synthetic peptides corresponding to the most frequent sequences of abductin. In particular, the 10 amino acid abductin peptide sequence FGGMGGGNAG, tandem repeated in the protein, and two related 25 and 40 amino acid polypeptides were synthesized. These peptides were studied with regard to secondary structure, self‐assembly, and polymer morphology. The results obtained with these peptides allow us to propose a preliminary structure‐elasticity relationship for abductin not dissimilar from that currently accepted for elastin.

A possible mechanism of elasticity relating abductin to elastin.

magnified image

A possible mechanism of elasticity relating abductin to elastin.
Folate Receptor‐Mediated Gene Delivery Using Folate‐Poly(ethylene glycol)‐Poly(L‐lysine) Conjugate
Authors: Cho Kyung Chul , Kim Sun Hwa , Jeong Ji Hoon , Park Tae Gwan
Published: June 2005

Summary: For efficient receptor‐mediated gene transfection, a new and simple formulation method based on using PEI and FOLPEGPLL conjugate was presented. Luciferase plasmid DNA and PEI were complexed to form slightly positive‐charged nanoparticles, onto which FOL‐PEG‐PLL conjugate was surface coated. With increasing the coating amount of FOL‐PEG‐PLL conjugate, the FOL‐PEG‐PLL/PEI/DNA complexes exhibited increased surface zeta‐potential values with concomitantly increased diameters, indicating that the PLL part was physically anchored on the surface of preformed PEI/DNA complexes with FOL moieties being exposed on the outside. The formulated complexes exhibited a considerably higher transfection efficiency against FOL receptor over‐expressing KB cells than FOL receptor deficient A549 cells. This was caused by an enhanced cellular uptake of the resultant complexes via a receptor‐mediated endocytosis process. The formulated complexes showed a higher gene expression level, even in the presence of serum, than the PEI/DNA or Lipofectamine/DNA complexes. This was attributed to the PEG chains present on the surface of complexes that could work as a protective shield layer against aggregation caused by non‐specific protein adsorption. The FOL‐PEG‐PLL/PEI/DNA complexes also demonstrated better cell viability than the PEI/DNA complexes.

1H NMR spectrum of FOL‐PEG‐PLL conjugate.

magnified image

1H NMR spectrum of FOL‐PEG‐PLL conjugate.
Water‐Soluble Nanoparticles from Random Copolymer and Oppositely Charged Surfactant, 3
Authors: Kizhakkedathu Jayachandran N. , Nisha C. K. , Manorama Sunkara V. , Maiti Souvik
Published: June 2005

Summary: In this report, we investigate the nanoparticle formation between random copolymers (RCPs) of methoxy‐poly(ethylene glycol) monomethacrylate (MePEGMA) and (3‐(methacryloylamino)propyl)trimethylammonium chloride (MAPTAC) and oppositely charged natural surfactants, sodium oleate and sodium laurate, using turbidimetric titration, steady‐state fluorescence, dynamic light scattering, and electron microscopy. Though sodium oleate and sodium laurate are sparingly soluble in water, the nanoparticle complexes formed between the RCPs and these surfactants are soluble in the entire range of compositions studied here, including the stoichiometric electronetural complexes. The spherical nature of these nanoparticle complexes is revealed by electron microscopic (EM) analysis. Dynamic light scattering (DLS) showed that the average diameters of the nanoparticles are in the range 50 to 150 nm, which is supported by EM analysis. Pyrene fluorescence experiments suggested that these soluble nanoparticles have hydrophobic cores, which may solubilize hydrophobic drug molecules. The polarity index (I1/I3) obtained from the pyrene fluorescence spectra and the conductometric measurements showed that the critical concentration of fatty acid salts needed to obtain nanoparticles are in the order of 10−4 M. Further, the complexation of such poorly water‐soluble amphiphilic surfactants with polymers offers a useful method for the immobilization of hydrophobic compounds towards water‐soluble drug carrier formulations.

The formation of water‐soluble nanoparticles by the self‐assembly of fatty acid salts upon interacting with oppositely charged poly(ethylene glycol)‐based polyions.

magnified image

The formation of water‐soluble nanoparticles by the self‐assembly of fatty acid salts upon interacting with oppositely charged poly(ethylene glycol)‐based polyions.
New Insights into Lamellar Twisting in Transcrystalline Polyethylene
Authors: Ratner Stanislav , Moret P. Mona , Wachtel Ellen , Marom Gad
Published: June 2005

Summary: The morphology of the transcrystalline layer grown by nucleating high density polyethylene on fibers of ultra high molecular weight polyethylene was investigated by microbeam synchrotron X‐ray diffraction. Scanning with a 2 micron step size, it was possible to determine that near the fiber surface, the polymer chains of the transcrystalline layer are oriented at an angle of approx. 41° with respect to the fiber axis. This is consistent with the lamellar fold surface (the {201} plane) being close to perpendicular to the fiber axis. The X‐ray data support gradual twisting of the lamellae about the growth direction (the orthorhombic crystallite b‐axis) at a rate of ∼0.85° per micron of radial distance from the fiber surface.

Polarized light micrograph of the transcrystalline layer in a PE/PE composite. The width of the fiber is approximately 20 μm.

magnified image

Polarized light micrograph of the transcrystalline layer in a PE/PE composite. The width of the fiber is approximately 20 μm.
Chain Extension and Cyclization of Telechelic Polysarcosines
Authors: Kricheldorf Hans R. , v. Lossow Colin , Schwarz Gert , Fritsch Detlef
Published: June 2005

Summary: Sarcosine N‐carboxyanhydride (Sar‐NCA) was polymerized with 1,12‐diaminododecane (DAD) or 1,13‐diamino‐4,7,10‐trioxatridecane (DATT) as initiators, and telechelic blocks having two secondary amino endgroups were obtained. Their structure was proven by 1H NMR and MALDI‐TOF mass spectrometry. The SEC measurements indicated narrow molecular weight distribution with polydispersity indices in the range of 1.1–1.2. These difunctional polysarcosines were reacted with three different coupling agents: 4,4′‐diisocyanatodiphenylmethane (MDI), N‐hydroxysuccinimide sebacate, and sebacoyl bisimidazolide. Although the 1H NMR spectra proved high conversions, only a moderate chain extension was observed. The MALDI‐TOF mass spectra indicated a high extent of cyclization, which limited the chain growth.

MALDI‐TOF mass spectrum of a DATT‐initiated polysarcosine after reaction with sebacoyl bisimidazolide.

magnified image

MALDI‐TOF mass spectrum of a DATT‐initiated polysarcosine after reaction with sebacoyl bisimidazolide.
Are Electrografted Polymers Chemisorbed or Physisorbed onto their Substrate?
Authors: Cuenot Stéphane , Gabriel Sabine , Jérôme Christine , Jérôme Robert , Duwez Anne‐Sophie
Published: June 2005

Summary: AFM‐based single‐molecule force spectroscopy was used to evaluate the mechanical strength of the link between a polymer and the substrate onto which the polymer is electrografted. Poly(N‐succinimidyl acrylate) was electrografted onto gold substrates and brought into contact with an aminothiol‐functionalized AFM tip. Bridging of single polymer chains resulting from the strong coupling between the activated esters on the polymer and amine groups on the tip was investigated. We found that the link between the polymer and the gold substrate can withstand a force far beyond the force characteristic for physisorption on gold.

magnified image
Photoinduced Polymerization of Thiophene Using Iodonium Salt
Authors: Yagci Yusuf , Yilmaz Faruk , Kiralp Senem , Toppare Levent
Published: June 2005

Summary: Thiophene was polymerized by means of UV irradiation using diphenyliodonium hexafluorophosphate as a photoinitiator. An initiation mechanism involving electron transfer from photochemically generated onium radical cations to thiophene was proposed. N‐Ethoxy‐2‐methylpyridinium hexafluorophosphate and triphenylsulfonium hexafluorophosphate were also found to be effective in facilitating the polymerization of thiophene. Polymerization is accompanied with the film formation on the surface of the reaction tube. The photochemically obtained polymers were characterized by FT‐IR, DSC, and SEM analyses and compared with those obtained by oxidative and electrochemical means. Electrical conductivities of the samples were measured by four‐probe technique.

Photograph of the polymerization mixture containing thiophene and iodonium salt in CH2Cl2 before (a), after 5 min of irradiation (b), and dried film (c).

magnified image

Photograph of the polymerization mixture containing thiophene and iodonium salt in CH2Cl2 before (a), after 5 min of irradiation (b), and dried film (c).
Streptomycin and EDTA decrease the number of desmin‐negative fibers following stretch injury
Authors: Willems Mark E. T. , Stauber William T.
Published: June 2005

Streptomycin and ethylene diamine tetraacetic acid (EDTA) were used to examine the role of extracellular calcium in stretch‐induced muscle injury. Streptomycin was injected in one group of rats, three times daily for 8 days (S, 300 mg.kg−1.day−1 intraperitoneally). In another group, EDTA was administered (150 mg.kg−1 IP) 20 min before and 24 h after the injury protocol. Untreated rats (C) served as controls. Muscle injury was produced by 40 stretches of active dorsiflexor muscles by ankle rotation from 80° to 130° (velocity 1.75 rad.s−1). Ten minutes after the injury protocols, all animals lost the same amount of isometric force at both low and high stimulation frequencies (20 HZ; S, 56 ± 6%; EDTA, 47 ± 7%; C, 55 ± 4%) and 120 HZ; S, 11 ± 3%, EDTA, 13 ± 3%; C, 11 ± 3%). Tibialis anterior (TA) muscles were removed after 48 h for morphometric analysis. In both streptomycin‐and EDTA‐treated rats, the percent of injured (i.e., desmin‐negative) myofibers in TA was reduced compared to untreated, injured muscles (S, 0.35 ± 0.08%; EDTA, 0.64 ± 0.19%; C, 1.81 ± 0.43%). Thus, streptomycin and EDTA treatment did not alter the development of muscle weakness (i.e., isometric force deficit), but almost abolished the histopathologic changes. This study shows that the mechanisms for muscle weakness and histopathologic changes (inflammation) following repeated muscle strains can largely be dissociated from each other and helps explain why there is no correlation between isometric force deficits and the number of pathologic cells. Muscle Nerve, 2005
Acquired nucleic acid changes may trigger sporadic amyotrophic lateral sclerosis
Authors: Armon Carmel
Published: June 2005

This article brings together evidence to support the hypothesis that acquired nucleic acid changes are the proximate causes, “triggers,” or “initiators” of sporadic amyotrophic lateral sclerosis (ALS). Clinical features that support this hypothesis include focal onset and spread, and the individualized rate of progression. Clues from the epidemiology of sporadic ALS include the increase in its incidence with age, suggesting accrual of time‐dependent changes, and the emergence of smoking, a known carcinogen, as its first “more likely than not” exogenous risk factor. The identification of any exogenous risk factor suggests that a large proportion of sporadic cases have a triggering mechanism susceptible to that factor. Ingestion of the products of cycad circinalis has been hypothesized to be implicated in causing Western Pacific ALS. Cycad contains both neurotoxic factors and carcinogens. The dissimilarity of Western Pacific ALS from neurotoxic diseases suggests a greater likelihood that the effects of DNA alkylation are its proximate cause. Muscle Nerve, 2005