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211.
Berit Borch-Iohnsen Kjell J. Nilssen Gunnar Norheim 《Biological trace element research》1996,51(3):235-247
Samples of liver (n=78) and kidney (n=60) from Svalbard reindeer (Rangifer tarandus platyrhynchus Vrolik) collected at four different seasons in Svalbard were analysed for their content of Cd, Pb, Cu, Zn, Mn, and Se. The
study shows that when animals are exposed to large seasonal variations in both the quality and quantity of food, it is crucial
to relate element concentrations to the physiological condition of the animal, e.g., to look at seasonal fluctuations in the
total element content of the different organs.
Deceased January 9, 1991. 相似文献
212.
Until the 1970’s, Trichinella spiralis (Owen 1835) was considered the only species within the genus Trichinella. Then T. pseudospiralis (Garkavi 1972) was classified as a separate species on the basis of morphological and biological features. The remaining morphologically homogenous “T. spiralis-group” has been split into 4 different species (or subspecies) on the basis of their biological and biochemical characteristics; T. nativa (Britov & Boev 1972), T. nelsoni (Britov & Boev 1972), T. spiralis sensu stricto and T. britovi (Pozio et al. 1992). 相似文献
213.
Molly Vernersson Gunnar Pejler Therese Kristersson Kjell Alving L. Hellman 《Immunogenetics》1997,46(6):461-468
As a step in the evolutionary studies of immunoglobulin E (IgE) and for the purpose of developing new reagents that will
facilitate a more detailed analysis of IgE-mediated inflammatory reactions in a large animal model, we here present the cloning
of the ε chain of IgE in the domestic pig (Sus scrufa). A partial cDNA clone for the ε chain of pig IgE was isolated by polymerase chain reaction (PCR) amplification using degenerate
primers directed against conserved regions in the second (CH2) and the fourth (CH4) constant domains of IgE. cDNA derived
from mRNA isolated from the spleen and lymph nodes of a pig actively sensitized with a protein extract from the nematode Ascaris suum was used as template. Screening of a spleen cDNA library with the partial cDNA clone as probe resulted in isolation of a
clone that contained the entire coding region. The nucleotide sequence was determined and was found to conform with the previously
identified mammalian ε-chain sequences. The highest degree of similarity was found to sheep IgE. A DNA construct encoding
a baculovirus signal sequence, a histidine hexapeptide, and the CH2-CH3-CH4 domains of the pig IgE ε chain was obtained by
PCR amplification. The construct was ligated into the baculovirus expression vector pVL1392. Infection of High Five insect
cells with recombinant baculovirus resulted in expression and secretion of a soluble 6 × His-CH2-CH3-CH4 protein product.
Received: 9 April 1997 / Revised: 28 May 1997 相似文献
214.
On the role of glucocorticoid receptors in brain plasticity 总被引:3,自引:0,他引:3
Kjell Fuxe Rochellys Diaz Antonio Cintra Maheep Bhatnagar Barbro Tinner Jan-Åke Gustafsson Sven-Ove Õgren Luigi F. Agnati 《Cellular and molecular neurobiology》1996,16(2):239-258
Summary 1. The mapping of glucocorticoid receptors (GR) in the rat central nervous system (CNS) has demonstrated their widespread presence in large numbers of nerve and glial cell populations also outside the classical stress regions.2. The present paper summarizes the evidence that glucocorticoids via GR in the CNS can act as lifelong organizing signals from development to aging. The following examples are given. (a) In the prepubertal and adult offspring, prenatal corticosterone treatment can produce long-lasting changes in striatal dopaminergic communication. (b) In adulthood, the evidence suggests complex regulation by adrenocortical hormones of neurotrophic factors and their receptors in the hippocampal formation. (c) In aging, the strongly GR-immunoreactive pyramidal cell layer of the CA1 hippocampal area appears to be preferentially vulnerable to neurotoxic actions of glucocorticoids, especially in some rat strains.3. Strong evidence suggests that each nerve cell in the CNS is supported by a trophic unit, consisting of other nerve cells and glial cells, blood vessels, and extracellular matrix molecules. Due to multiple actions on nerve and glial cell populations of the different trophic units, the glucocorticoids may exert either an overall trophic or a neurotoxic action. It seems likely that with increasing age, the endangering actions of glucocorticoids on nerve cells prevail over the neurotrophic ones, leading to reduced nerve cell survival in some trophic units. 相似文献
215.
Kjell Andersson Chun-Mei Zhao Duan Chen Frank Sundler Rolf Håkanson 《Cell and tissue research》1996,286(3):375-384
The oxyntic mucosa of the mammalian stomach is rich in endocrine cells, such as ECL cells, A-like cells, somatostatin cells,
D1/P cells and, in some species, enterochromaffin cells. The various endocrine cell types can be distinguished on the basis
of their characteristic cytoplasmic granules and vesicles. The ECL cells contain numerous large secretory vesicles and relatively
few, small electron-dense granules and small clear microvesicles. We have suggested that in the rat the ECL cells contain
most of the gastric histamine with the secretory vesicles as the major histamine storage site in these cells. α-Fluoromethylhistidine
is an irreversible inhibitor of histidine decarboxylase, the histamine-forming enzyme. We have previously shown that this
enzyme inhibitor depletes histamine from the ECL cells in the rat and reduces the number of secretory vesicles in the cytoplasm.
In the present study, we have examined whether α-fluoromethylhistidine affects the ECL cells in other species and whether
it affects other types of endocrine cells in the oxyntic mucosa of the rat. Mice, rats and hamsters were treated with the
inhibitor (3 mg/kg per h) via minipumps subcutaneously for 24 h. This treatment lowered the oxyntic mucosal histamine concentration
by 65–90% and the number and volume density of the secretory vesicles by 85–95% in the ECL cells of the three species examined.
In contrast, the number and volume density of granules and microvesicles were not greatly affected. No evidence was found
for an effect of α-fluoromethylhistidine on A-like cells, somatostatin cells or D1/P cells of the rat stomach, suggesting that, unlike the ECL cells, they do not contain histamine.
Received: 18 January 1996 / Accepted: 23 May 1996 相似文献
216.
We studied egg and larval mortality factors in arctic populations of the bud-galling sawfly, Euura mucronata (Hartig) on three willow species (Salix glauca L., S. phylicifolia L., and S. lapponum L.) and the quality of resources (shoot length of willows) required for egg-laying. The survival was independent of latitude.
There was a positive correlation in survival on different willow species among sampling sites, indicating that similar, locally
operating factors affected survival. Host plant-based mortality factors were dominant and caused 17.9–48.0% mortality in eggs
and 6.6–44.1% mortality in larvae. Parasitoids and inquilines caused relatively low and variable rates of mortality. Parasitoids
were absent from several of the northernmost populations, but caused up to 11.0% mortality at southern sites. Mortality caused
by inquilines was minor in other areas except in some sites in the Taymyr Peninsula, where it varied from 0 to 23.1%. E. mucronata laid eggs on the longest shoots available. Plant vigour as measured by shoot length decreased toward the north, and densities
of galls were positively correlated with plant vigour. The difference in length between galled and ungalled shoots was 2.0-
to 4.6-fold. Absence of E. mucronata in the most northern populations of willows was apparently caused by insufficient shoot growth. Short shoots failed to provide
sufficient resources for successful development of galls. Our results suggest that the quality of host plants is the main
factor determining abundance and distribution of E. mucronata in arctic areas.
Received: 10 February 1997 / Accepted: 2 May 1997 相似文献
217.
Fredrik S?dersten Stina Ekman Maija-Leena Eloranta Dick Heineg?rd Jayesh Dudhia Kjell Hultenby 《Matrix biology》2005,24(5):376-385
The structure and organisation of the extracellular matrix, and in particular the axial alignment of type I collagen fibrils, are essential for the tensile strength of tendons. The resident tenocytes synthesize and maintain the composition of the extracellular matrix, which changes with age and maturation. Other components of the extracellular matrix include less abundant collagen types II, III, V, VI, XII, proteoglycans and glycoproteins. Cartilage oligomeric matrix protein (COMP) is an abundant non-collagenous pentameric glycoprotein in the tendon, which can bind to collagen types I and II. The function of COMP in the tendon is not clear, but it may act as a catalyst in fibrillogenesis. Its concentration changes with age, maturation and load. The present study delineates the ultrastructural distribution of COMP and its correlation to collagen fibril thickness in different compartments in two flexor tendons from horses of different ages (foetus, 8 months, 3 years, 12 years). The immunolabeling for COMP was higher in the superficial digital flexor tendon compared with the deep digital flexor tendon and it increased with the age of the animal, with the highest concentration in the 3-year-olds. Fibril diameter differed between age groups and a more homogenous fibril population was found in the fetal tendons. A positive correlation between high COMP immunolabeling and the percentage of small fibrils (<60 nm) were present in the SDFT. COMP immunolabeling was enriched at the gap region of the collagen fibril. In situ hybridization revealed the strongest expression in tendons from the 3-year-old horses whereas there was no expression in foetal tendon. 相似文献
218.
Robert E. Chapin Timothy Winton William Nowland Nichole Danis Steven Kumpf Kjell Johnson Aleasha Coburn Jan‐Bernd Stukenborg 《Birth defects research. Part B, Developmental and reproductive toxicology》2016,107(6):225-242
The last two decades have seen an increasing search for in vitro models that can replace the use of animals for safety testing. We adapted the methods from a recent nonquantitative report of spermatogenesis occurring in ex vivo mouse testis explants and tried to develop them into a screening assay. The model consisted of small pieces of neonatal mouse testis (testis “chunks”), explanted and placed on pillars of agarose or chamber inserts, and cultured at the air–liquid interface. A peripheral torus‐shaped zone in these explants would often contain tubules showing spermatogenesis, while the middle of each chunk was often necrotic, depending on the thickness of the tissue. The endpoint was histology: what proportion of tubules in the “permissive torus” actually contained healthy pachytene spermatocytes or spermatids? Extensive statistical modeling revealed that a useful predictive model required more than 60% of these tubules to show spermatogenesis. Separately, the logistics of running this as a predictive assay require that the controls consistently produce ≥ 60% tubules with pachytenes and round spermatids, and achieving this level of spermatogenesis reliably and consistently every week proved ultimately not possible. Extensive trials with various media additions and amendments proved incapable of maintaining the frequency of spermatogenic tubules at consistently ≥ 60%. Congruent with Schooler's “decline effect”; generally, the more often we ran these cultures, the worse the performance became. We hope that future efforts in this area may use our experience as a starting point on the way to a fully productive in vitro model of spermatogenesis. 相似文献
219.
Dr. Lennart G. Ohlsson Kjell U. I. Johansson Dick R. Nässel 《Cell and tissue research》1989,256(1):199-211
Summary The adult optic lobes of the blowfly Calliphora erythrocephala were found to be innervated by more than 2000 neurons immunoreactive to antisera raised against the neuropeptides FMRFamide, its fragment RFamide, and gastrin/cholecystokinin (CCK). All of the CCK-like immunoreactive (CCK-IR) neurons also reacted with antisera to RFamide, FMRFamide and pancreatic polypeptide. A few RFamide/FMRFamide-like immunoreactive (RF-IR) neurons did not react with CCK antisera; they reacted instead with antisera to Leu-enkephalin and Met-enkephalin-Arg6-Phe7. The RF-IR neurons are, thus, heterogeneous with respect to their contents of immunoreactive peptides. Two of the RF-IR neuron types innervating the adult optic lobes could be traced in their entirety only after following their postembryonic development, because of the complexity of the trajectories of the immunoreactive neuronal process in the adult insect. The majority of the cell bodies of the RF-IR and CCK-IR neurons lie within the optic lobes and are derived from imaginal neuroblasts of the inner and outer optic anlagen. Six of the peptidergic neurons are, however, metamorphosing larval neurons with their cell bodies in the central part of the protocerebrum. The full extent of immunoreactivitiy is not attained in some of the neurons until the late pupal or early adult stage. The larval optic center was also found to be innervated by neurons immuno-reactive with both RFamide and CCK antisera. The cell bodies of these RF-IR/CCK-IR neurons are located near the developing lamina (one on each side). In the 24 h pupa, the cell bodies of these neurons are still immunoreactive, but thereafter they cannot be immunolabeled apparently due to cell death or a change in transmitter phenotype. 相似文献
220.
Michele Zoli Fabio Benfenati Emilio Merlo Pich Gino Toffano Kjell Fuxe Luigi F. Agnati 《Neurochemistry international》1990,16(4):437-449
Some effects of aging processes on the neurochemical features of central transmitter-identified neuronal populations have been investigated by means of immunocytochemistry and receptor autoradiographic techniques coupled with image analysis. A selective decrease of tyrosine hydroxylase immunoreactivity in the ventrolateral region of the arcuate nucleus in aged rats was observed. The level and turnover (recovery after irreversible blockade of monoamine receptors with the peptide coupling agent N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline) of 2-adrenergic ([3H]paraaminoclonidine binding) and D2 dopamine ([3H]spiperone binding) receptors were reduced in most regions of the rat brain. Peptide receptors showed a more complex pattern of change, since while μ opiate receptors (preferentially labeled with [3H]etorphine binding) were reduced in the old animals, δ opiate ([3H]DSTLenkephalin binding) receptors were affected only in certain areas. The effect of irreversible blockade of monoamine receptors on μ and δ opiate receptors was also studied in young adult and aged rats. A δ but not μ opiate receptor up-regulation was observed after monoamine receptor blockade in the young adult animals. This effect was greatly reduced in the n. caudatus-putamen, n. accumbens and tuberculum olfactorium of the old animals. 相似文献