bluuebunny/crossref_metadata_2025_split huggingface dataset:
Insulin receptors in Xenopus laevis liver and forelimb regenerates and the effects of local insulin deprivation on regeneration
Authors: Cowan Bryce J. , Foty Ramsey A. , Liversage Richard A. 
Published: June 2005

AbstractAs forelimb regeneration in Xenopus laevis is mainly a cell proliferative event which results in a spike‐shaped appendage, we set out to examine the possibility that insulin is a growth‐promoting factor in this process. The objectives were 1) to detect the presence of insulin receptors (IRs) in the liver (a specific target organ for insulin) and IRs in the forelimb regenerates of X. laevis, 2) to determine whether the receptor is similar to IRs identified in other organisms, and 3) to absorb insulin locally by implanting anti‐insulin antibody‐soaked hydrolyzed polyacrylamide beads into regenerating forelimb outgrowths in order to assess the effects of insulin deprivation on regeneration. The results show that IRs are present in Xenopus liver plasma membranes (XLPM) as well as in plasma membranes of 21 day forelimb regenerates. Insulin binding to this receptor is time‐dependent and specific, as unlabeled bovine insulin competes with radioiodinated insulin for binding to XLPM more effectively than insulin‐like growth factor‐I, guinea pig insulin, or glucagon. Scatchard analysis of insulin binding to XLPM describes a two binding site receptor possessing a low affinity (0.16 nM−1), high capacity (3.2 ± 0.9 pM/mg) binding site and a high affinity (2.7 nM−1), low capacity (0.5 ± 0.3 pM/mg) binding site. The holoreceptor has a molecular mass of 380 kDa. The reduced receptor has subunits of 130 kDa and 95 kDa. The 95 kDa subunit undergoes autophosphorylation following insulin stimulation. Implantation of hydrolyzed poly‐acrylamide beads, saturated with anti‐insulin antibody, into regenerating Xenopus Forelimbs significantly impeded development of the regenerates and, therefore, demonstrates that insulin is required for growth of Xenopus forelimb regenerates. © 1995 Wiley‐Liss, Inc.
Purification and characterization of fatty acid‐binding protein from aerobic muscle of the antarctic icefish Chaenocephalus aceratus
Authors: Londraville Richard L. , Sidell Bruce D. 
Published: June 2005

AbstractIntracellular fatty acid‐binding protein is purified and characterized from aerobic skeletal muscle of the Antarctic icefish Chaenocephalus aceratus. Molecular mass of C. aceratus FABP (CA‐FABP) is 14,936 Da as estimated by electrospray mass spectrometry. CA‐FABP is expressed at an intracellular concentration of 0.984 ± 0.115 mg CA‐FABP g−1 wet weight aerobic muscle and binds 0.859 ± 0.013 moles oleic acid per mole of protein at a physiological temperature of 0°C. Dissociation constants (Kds) for various fatty acid ligands range from 1.38 to 2.71 μM; Kds are not significantly different among palmitic acid (16:0), palmitoleic acid (16:1), and oleic acid (18:1). Competition assays reveal that CA‐FABP does not have preferential affinity for the very‐long‐chain, polyunsaturated fatty acids that are common in Antarctic fish (e.g., docosahexaenoic acid; 22:6). Partial amino acid sequence from CA FABP aligns with mammalian heart‐type FABPs with as high as 74% identity. These data are strikingly similar to mammalian values, yet they are derived from an organism that is distant from mammals in terms of phylogeny, body temperature, and physiology. This suggests that the FABP family is conserved not only in primary sequence, but also in its physiological properties. © 1995 Wiley‐Liss, Inc.
Effect of changing from a short‐day to long‐day photoperiod on the breeding season of the brushtail possum (Trichosurus vulpecula)
Authors: Gemmell Robert T. , Sernia Conrad 
Published: June 2005

AbstractIn Queensland, possums (Trichosurus vulpecula) in the wild and in captivity first give birth during March and April and continue to give birth throughout the year until November. The possum has a gestation length of 17.5 days, gives birth to one young, and lactation continues for approximately 180 days. If the newborn possum is removed during the breeding season, the possum will ovulate approximately 9 days later and give birth approximately 26 days after removal of the pouch young (RPY). Repeated RPY may be used to determine the duration of the breeding season. In this study, the effect on the breeding season of a marked change in photoperiod from a short‐day to a long‐day was examined by comparing three groups of possums in different photoperiods for 13 months. One group of five female and two male possums (group A) was housed in a natural photoperiod and a second group (B) was housed in a short‐day photoperiod (10 h light: 14 h dark) throughout the study. The third group (C) was housed in a short‐day photoperiod until each possum gave birth, the pouch young was removed, and the possum transferred to a long‐day photoperiod room (14 h light: 10 h dark) for the remainder of the study. The possums held in a natural photoperiod, group A, gave birth to a total of 27 births in the one breeding season from March to October. The 5 possums of group B, held in a short‐day photoperiod, gave birth to a total of 28 births, from January through August, no births in September and October, and 3 births again in November and December. With group C, a total of 15 births was observed, 10 of them after transfer to a long‐day photoperiod. All possums gave birth in January and were transferred to the long‐day photoperiod following RPY. There followed four births in February and March and a further six births from July to November. In conclusion, short‐day photoperiods can hasten the onset of breeding activity in possums and are required for the maintenance of the breeding season. © 1995 Wiley‐Liss, Inc.
Entrainment of circadian system under variable photocycles (T‐photocycles) alters the critical daylength for photoperiodic induction in blackheaded buntings
Authors: Kumar Vinod , Kumar B. Sanjay 
Published: June 2005

AbstractThe present study was designed to investigate the photoperiodic responses of blackheaded buntings to various T‐photocycles [T =the period length of light:dark (LD) cycle]. Two series of experiments were performed. In series I, groups of buntings (n =8‐12) were exposed to LD cycles of 22 to 26 hr with photoperiods of 6, 10, or 11 hr (T22 =6L:16D, 10L:12D, 11L:11D; T24 =6L:18D, 11L:13D; T26 =6L:20D, 11L:15D). Among these groups, birds subjected to 11L:11D showed heavy deposition of fat, weight gain, and testicular recrudescence, a response that is characteristic of long day (≥ 12 hr photoperiod per day) photostimulation, indicating that a T‐photocycle of less than 24 hr (T =22 hr) was photoinductive in buntings when presented with a photophase long enough to interact with the photoinducible phase (ϕi), located in the middle of the photocycle. Experiments in series II included an interrupted‐night lighting protocol with a main photophase of 6 hr and 1‐hr light break in photocycles of T =22 hr, T =24 hr, and T =26 hr. The results revealed that a 1‐hr light pulse was inductive when it was introduced in the middle of the photocycles, and, thus, was coincident with the ϕi. It is suggested that the critical daylength for photoperiodic induction in buntings is altered as a result of entrainment to various T‐photocycles. © 1995 Wiley‐Liss, Inc.
The elasmobranch thymus: Anatomical, histological, and preliminary functional characterization
Authors: Luer Carl A. , Walsh Catherine J. , Bodine A. B. , Wyffels Jennifer T. , Scott Thomas R. 
Published: June 2005

AbstractThymi from 22 species of elasmobranch fish (class Chondrichthyes) were examined. Information on the anatomical location, organ arrangement, and cellular composition of the thymi as a function of sexual maturation as well as preliminary characterization of thymocyte functional activities are reported. Most of the sharks, skates, rays, and guitarfish reported herein represent species from which thymus had not been previously documented. The elasmobranch thymus is bilateral and situated dorsomedial to both gill regions. Although its size and location relative to the surrounding musculature varied with sexual maturation, thymus was confirmed in every specimen examined. Separate cortical and medullary regions resembling the cortex and medulla of mammalian thymi were consistent features among all elasmobranch thymi examined. Tissue imprints confirmed the presence of thymocytes ranging in size from small, darkly staining cells to large, lightly staining blast‐like cells. Large thymic cells, containing cell debris or intact thymocytes were often observed. In vitro functional assays including cytochemical visualization of lysosomal enzymes characteristic of stage‐specific thymocyte maturation, and the presence of nuclear and cell surface biochemical markers associated with immature thymocytes suggest functional roles for elasmobranch thymi similar to those of the thymi of higher vertebrate classes. Proliferation of senescent nurse shark thymocytes in culture as determined by cell flow cytometry and tritiated thymidine incorporation was also similar to in vitro responses typical of higher vertebrate mitogen‐independent thymocyte proliferation. © 1995 Wiley‐Liss, Inc.
Uptake of high‐density lipoprotein by Y‐organs of the crab Cancer antennarius: III. Evidence for adsorptive endocytosis and the absence of lysosomal processing
Authors: Kang Byoung K. , Spaziani Eugene 
Published: June 2005

AbstractEcdysteroid hormones in crustaceans are synthesized from cholesterol in the Y‐organs. Circulating cholesterol is bound to high‐density lipoprotein (HDL). Experiments were conducted to find the mode of cholesterol uptake by Y‐organ cells. The working hypothesis is as follows: Cholesterol is taken up by endocytosis of the entire HDL‐cholesterol complex. HDL was doubly labeled in the apolipoprotein and cholesterol components with 125I and 3H, respectively. The time courses of uptake of the two labels by Y‐organ segments in vitro were parallel throughout 24 hr of incubation. Chloroquine, an inhibitor of lysosomal function, had no effect on the uptake and degradation of HDL. Cycloheximide, an inhibitor of protein synthesis, depressed HDL uptake. Transmission electron microscopy of Y‐organ tissue showed features characteristic of adsorptive endocytosis, including coated pits in the plasma membranes and their invagination and vesiculation. Visualization of HDL with immunogold binding showed profiles consistent with endocytosis. Quantitation of the distribution of HDL‐gold particles indicated that about 75% were associated with cellular formed elements, but not with lysosomes, and significantly more particles overall were present in cells from de‐eyestalked crabs than those from intact crabs. These data demonstrate that (a) cholesterol‐carrying HDL is taken into Y‐organ cells by adsorptive endocytosis, (b) its uptake is dependent on de novo protein synthesis, (c) its intracellular processing is independent of lysosomal enzymes, and (d) its uptake is depressed by the molt‐inhibiting hormone secreted by the eyestalks. © 1995 Wiley‐Liss, Inc.
Age‐dependent changes in thymuses in the European common frog, Rana temporaria
Authors: Plytycz Barbara , Mika Joanna , Bigaj Janusz 
Published: June 2005

AbstractThe thymus of the adult frog Rana temporaria is generally small each winter and grows through the spring to reach a large size each summer. The summer thymus has a cortex full of small thymocytes and a medulla in the centre, whereas the winter atrophy is manifested by a loss of distinction between cortex and medulla, an abundance of cells filled with secretory granules, and the formation of intercellular cysts. These seasonal changes are superimposed on age changes. The thymus grows rapidly in froglets. The differences in weight and cell number between winter and summer organs are strongest in middle‐aged animals (3–6 years old) and decrease in old specimens. The thymus slowly involutes with age, this being connected with increasing winter atrophy, leading to the formation of huge cysts that fill almost the whole organ in the oldest individuals. In senescent frogs (around 10 years old) seasonal differences still concern corticomedullary division but without pronounced fluctuations in thymic size. The skeletochronological technique applied here for age estimation underestimated rather than overestimated the real age of old animals. © 1995 Wiley‐Liss, Inc.
Development of electrical activity in regenerating aggregates of hydra cells
Authors: Itayama Tomoaki , Sawada Yasuji 
Published: June 2005

AbstractThe development of electrical activity in aggregates of dissociated hydra cells was investigated. Both the number of events and the distribution of amplitude of electrical pulses during the process of regeneration were determined. Correlations between electrical pulses at two separate positions on an aggregate were also examined as regeneration progressed. The main results were as follows: From the measured frequency and amplitude of pulses, together with the correlations between pulses at two different sites, we could observe the way in which contraction pulses developed in regenerating aggregates. The percentage of the electrical pulses of large amplitude increased about 20 hr after the start of regeneration. The correlation between electrical pulses measured at two sites separated by 0.3 mm also increased at about 20 hr, reaching about 80% at 40 hr. The results suggest the possible details of the reorganization of the conduction system for contraction pulses among cells in a regenerating aggregate of hydra cells. © 1995 Wiley‐Liss, Inc.
Toward a gene therapy for duchenne muscular dystrophy
Authors: Dunckley Matthew G. , Piper Tony A. , Dickson George 
Published: June 2005

AbstractDuchenne muscular dystrophy (DMD) is a wasting disease of muscle caused by mutations in a single gene on the X chromosome. Because no effective treatment is available, the disease inevitably is fatal by the third decade of life. Hence, the use of gene transfer technology to correct the biochemical defect (dystrophin‐deficiency) in muscle fibers of DMD patients may provide a promising therapeutic strategy. This review outlines recent progress toward understanding the molecular pathology of DMD, including identification of novel products of the DMD gene expressed in the nervous system and their involvement in neurological defects in DMD patients. We summarize germ‐line (transgenic) and somatic gene transfer studies performed on the mdx mouse model of DMD, using recombinant cDNA molecules. In light of these results, we discuss areas for future study, such as refinement of viral‐mediated gene transfer to muscle, and the prospects for gene therapy for human DMD patients. © 1995 Wiley‐Liss, Inc.
Self‐injurious behavior as endogenous neurochemical self‐administration
Authors: Thompson Travis , Symons Frank , Delaney Dawn , England Cindy 
Published: June 2005

AbstractThe compulsive and deeply disturbing character of self‐injurious behavior (SIB) makes it one of the most difficult behavior problems to understand scientifically and treat clinically. We review evidence implicating endogenous opioid peptides and the neurotransmitter dopamine in SIB. Next, we describe similarities between the self‐administration of cocaine and morphine by laboratory animals and self‐injury by people with mental retardation. We discuss shared behavioral and neurochemical properties that suggest common mechanisms that may be responsible for both the persistent, damaging behavior patterns characteristic of some forms of SIB and the addictive self‐administration of cocaine and morphine. Multifaceted treatment approaches are explored, based on a better understanding of underlying mechanisms. © 1995 Wiley‐Liss, Inc.
The nature and consequences of fragile X syndrome
Authors: Bailey Donald B. , Nelson David 
Published: June 2005

AbstractFragile X syndrome, the leading known inherited cause of mental retardation and developmental disabilities, is caused by a trinucleotide repeat expansion in the 5′ untranslated region of the FMR1 gene in Xq27.3 Research during the pat five years has documented the genetic abnormalities that cause this syndrome and described the impairments, disabilities, and disadvantages asslociated with it. Future research is needed to foucs on genetics and neurobiology, screening and early identification, biomedical treatments, psychoeducational interventions, and family adaptation and support. © 1995 Wiley‐Liss, Inc.
Modeling the natural history of the fragile X gene
Authors: Sherman Stephanie 
Published: June 2005

AbstractElucidation of the nature of the mutational process that leads to fragile X syndrome and other triplet repeat disorders poses an interesting problem. At present, no experimental model systems are available to study the expansion process. Moreover, data from fragile X family studies reveal only the behavior of the highly expanded form of the mutation. Thus, mathematical modeling of the mutational process has become an important tool for use in examining the nature and fate of the fragile X gene. Such methods can be used to generate predictions that can be tested using empirical data. This article reviews these models and discusses the predicted allele frequencies at equilibrium and the approach to equilibrium. © 1995 Wiley‐Liss, Inc.
Interaction in teratogenesis: Actinomycin D, puromycin and deoxyguanosine
Authors: Pierro Louis J. , Coghill Joanne E. 
Published: June 2005

AbstractAbnormal development of the embryonic axis is one consequence of injection into the yolk sacs of 48‐hour chick embryos of each of the following teratogens: actinomycin D, puromycin, deoxyguanosine. Rumplessness and trunklessness are consequences of treatment with actinomycin D or puromycin; thoracic constrictions are consequences of treatment with deoxyguanosine. Treatment with both actinomycin D and deoxyguanosine, under certain conditions of dosage and developmental timing, results in an increase in the frequency of rumplessness and trunklessness; the same is true for combined treatment with puromycin and deoxyguanosine. Although deoxyguanosine treatment of 72‐hour embryos is also associated with rumplessness, evidence is presented that deoxyguanosine‐induced rumplessness does not contribute to the effects obtained with embryos treated at 48 hours incubation age with these combinations of teratogens. Treatment with both actinomycin D and deoxyguanosine can result in an increase in the frequency of thoracic constrictions; treatment with both puromycin and deoxyguanosine, in a decrease. These interactions in teratogenesis between deoxyguanosine and actinomycin D and between deoxyguanosine and puromycin indicate that the distribution in the embryo of each teratogen is more widespread than suggested by the morphological consequences associated with each individually.
Teratogenic action of carbonic anhydrase inhibitors in the rat
Authors: Wilson James G. , Maren Thomas H. , Takano Kiichi , Ellison Arthur 
Published: June 2005

AbstractAcetazolamide and ethoxzolamide incorporated into the diet of pregnant rats at 0.3% or 0.6% level caused localized appendicular malformation typically affecting the distal, postaxial part of the right forelimb. Other malformations and intrauterine death were also more frequent than in the offspring of untreated rats.Treatment on day 10 or 11 of gestation with 1000 mg/kg of acetazolamide injected subcutaneously also produced a high incidence of typical abnormalities but similar treatment on day 9 or 12 failed to do so. The susceptible period of rat embryos to this agent is thus defined as the tenth and eleventh days.Analysis of maternal blood after teratogenic treatment revealed that both acetazolamide and ethoxzolamide produced metabolic acidosis but little change in other electrolytes except potassium, which was sharply reduced. It was not possible to prevent the occurrence of characteristic malformations by supplemental dosing with potassium. The production of litters with acetazolamide‐induced defects was associated with loss of maternal weight after treatment exceeding 10% of pretreatment weight. It has not been possible to produce typical defects using the potent diuretic furosemide.Analysis of embryos from untreated females revealed that carbonic anhydrase does not appear in measurable amounts in the developing rat until the thirteenth day of gestation, making highly unlikely the possibility that the drug's teratogenic action is associated with carbonic anhydrase inhibition in the embryo.
Analysis of trypan blue induced teratogenesis in Rana pipiens embryos
Authors: Greenhouse Gerald , Hamburgh Max 
Published: June 2005

AbstractFertilized Rana pipiens eggs were treated with 0.5% solution of trypan blue in spring water. The stage at which the dye was added and the duration of exposure were varied.The first signs of aberrant development appeared at late stage 13 at which time the neural folds were abnormal and elongation of the body axis was inhibited. Subsequent development resulted in microcephalic larvae with foreshortened trunks and kinked or malproportioned tails. Such embryos never exhibited spontaneous muscular contractions although they may survive for 10 to 12 days and come to resemble stage 21 larvae.Microscopic analysis revealed that (1) the notochord was either completely absent or present only in the anterior half of experimental embryos, (2) adjacent to the notochordal abnormalities the lateral mesoderm formed an unsegmented mass whose left and right sides fused beneath the neural tube, and (3) malformations of the forebrain included absence of the diencephalon, optic cups, and cranial ganglia.Trypan blue was never found within the cells of the embryos.The critical period of response to trypan blue extended from stage 10 through stage 14. Animals growing in dye solution since fertilization but removed to fresh spring water prior to stage 10 differentiated normally.
Direct effects of 6‐aminonicotinamide on the developing rat embryo in vitro and in vivo
Authors: Turbow M. M. , Chamberlain J. G. 
Published: June 2005

AbstractGraded dosages of the niacin antimetabolite 6‐aminonicotinamide (6‐AN) were incorporated in the culture media of explanted day 10 rat embryos or injected directly into amniotic cavities of day 15 embryos. Regardless of the route of administration the resultant decreased growth and abnormal development were related to the concentration of the antimetabolite. Culturing embryos for 22–26 hours with 5 to 20 μg 6‐AN progressively interfered with subsequent somite growth and cardiovascular function. Addition of nicotinamide (NAM) to the cultures prevented the deleterious effects of the antimetabolite. Following infra‐amniotic injections, 54 to 94% of the implantation sites given 10 to 100 μg 6‐AN exhibited resorbed fetuses or young with abnormal palates, brains, or eyes by day 21 of gestation. The types of defects found in the present study were similar to those observed following maternal treatment with 6‐AN. Direct applications of this teratogen to isolated or in utero rat embryos resulted in decreased growth, increased fetal death, and congenital abnormalities without significant changes in maternal tissues.
Experimental production of congenital cardiovascular malformations in rats by salicylate poisoning
Authors: Takacs Eva , Warkany Josef 
Published: June 2005

AbstractCongenital cardiovascular malformations were produced in offspring of rats that received salicylates during the organogenetic period of gestation. The most frequent anomalies encountered were transposition of the aorta to the right ranging from “overriding of the aorta” to complete transposition. The doses necessary to produce such malformations in rats are compared with those used in human beings for therapeutic and suicidal purposes.