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Biomedical subjects

M Nilsson

Publications and source records attributed to M Nilsson.

At least 163 records · Page 9Linked to original sources

Some characteristics of the quality of life in old age illustrated by means of Allardt's concept.

This study illustrates some characteristics of the quality of life in old age when ageing is seen as a continued human development. In the Kungsholmen Project 87 healthy elderly persons were asked about the quality of their lives. Allardt's definition of quality of life was used as the conceptual framework for the content analysis. The findings indicate that the dimensions of loving and being, as Allardt describes them, take on a different meaning and the material things in the having dimension become less important. The differences point to another meaning of the quality of life in old age. The emphasis is on health and independence, contentment and a peaceful life, personal integrity in terms of a moral and a caring attitude. The findings tend to be in accordance with the successful ageing as described in Erikson's theory of psychosocial development and in Tornstam's theory of gerotranscendence. To gain a deeper understanding of this complex phenomenon, qualitative methods which go beyond definitions are required.

Activities of Daily Living↗

Inhibitory activity of the equine infectious anemia virus major 5' splice site in the absence of Rev.

The major 5' splice site of equine infectious anemia virus (EIAV) conforms to the consensus 5' splice site in eight consecutive positions and is located immediately upstream of the gag AUG. Our results show that the presence of this 5' splice site on the EIAV gag mRNA decreases Gag production 30- to 60-fold. This is caused by inefficient nuclear mRNA export and inefficient mRNA utilization. Inhibition could be overcome by providing human immunodeficiency virus type 1 Rev/Rev-responsive element, human T-cell leukemia virus type 1 Rex/Rex-responsive element, or simian retrovirus type 1 constitutive transport element. In addition, inhibition could be abolished by introducing single point mutations in the 5' splice site or by moving the 5' splice site away from its natural position immediately upstream of the gag AUG. This demonstrates that both maintenance of a perfect consensus 5' splice site and its proper location on the mRNA are important for inhibitory activity of the EIAV major 5' splice site.

Base Sequence↗

Quantitative computed tomography of trabecular bone in the mandible.

OBJECTIVE: To evaluate the potential use of quantitative computed tomography (QCT) for the assessment of bone mineral density of the edentulous mandible prior to implant placement. METHODS: Ten 2 mm thick CT slices of anterior and posterior edentulous sections from 15 mandibles were obtained perpendicular to the buccal and lingual plates. The bone mineral density, expressed as the amount of calcium hydroxyapatite (mg cm-3) of the trabecular bone, was calculated using a method that takes into account the influence of fat. RESULTS: The variation of bone mineral density between mandibles was high. Anterior sections showed higher values than posterior sections and a variation was found within sections of the same mandible. CONCLUSION: CT provides a site-related measure of the bone mineral density in the mandible and appears potentially useful as a non-invasive method to determine a parameter that may reflect bone quality prior to implant placement.

Aged↗

Effects of insulin-like growth factor I on growth, epithelial barrier and iodide transport in polarized pig thyrocyte monolayers.

The effects of insulin-like growth factor I (IGF-I) on mitogenesis, epithelial barrier function and transepithelial iodide transport were studied in confluent, polarized monolayers of pig thyrocytes cultured on filter in Transwell bicameral chambers. The growth rate in controls cultured in 1% fetal calf serum was low. Insulin-like growth factor I stimulated dose-dependently the incorporation of [3H]thymidine, maximally at 100 ng/ml, which corresponded to an increase of DNA content by 60% after 6 days. Thyrotropin (1 mU/ml) alone did not stimulate cell multiplication but inhibited partially the stimulatory effect of IGF-I. Insulin-like growth factor I (100 ng/ml) increased within 10 min the transepithelial potential difference, which remained elevated for several days, but did not significantly change the transepithelial resistance. When added together, IGF-I reinforced the effects of TSH on potential difference (increase) and resistance (decrease). A preserved epithelial barrier in IGF-I-treated cultures was confirmed by observing a normal immunolocalization of the tight junction protein ZO-1 and an unchanged ultrastructure of the junctional complex. Insulin-like growth factor I increased the transepithelial flux of 125I- in the basal-to-apical, but not in the opposite, direction. Stimulation of iodide transport by IGF-I was modest after 2 days and pronounced after 6 days. In comparison, TSH-stimulated iodide transport was higher after 2 days but lower after 6 days. Both TSH and IGF-I were strongly synergistic, after 6 days amounting to a 90-fold increase over the control basoapical 125I- transfer. The simultaneous accumulation of 125I- in the cell layer was increased two- to fourfold by IGF-I and/or TSH. In conclusion, IGF-I is able to induce growth in preformed monolayers of pig thyrocytes cultured on permeable filter. During these conditions, the mitogenic effect of IGF-I is partially inhibited by TSH, which has no growth-promoting action on its own. The transepithelial transport of iodide and bulk electrolytes is altered by IGF-I without affecting the epithelial barrier function. Specifically, IGF-I up-regulates the activity of the basolateral iodide pump and increases the iodide permeability of the apical plasma membrane. The action of IGF-I on iodide transport is independent of, although synergistic with, that of TSH. The findings support the notion that IGF-I may be an important regulator of thyroid growth and differentiated functions.

Animals↗

Primary culture of human thyrocytes in Transwell bicameral chamber: thyrotropin promotes polarization and epithelial barrier function.

Epithelial properties of thyrocytes are difficult to maintain in conventional cell culture systems. We used bicameral chambers (Transwell) in attempts to establish a functional epithelium of thyrocytes of human origin. Thyroid follicle segments were isolated by collagenase digestion of paradenomatous tissue obtained at surgery for follicular adenoma and of tissue from glands with Graves' disease. After careful separation from connective tissue and single cells by centrifugation, the follicles were plated at high density on the collagen-coated filter of the chambers and cultured in Eagle's essential medium (EMEM) containing 10% fetal calf serum (FCS) or Coon's modified Hams medium enriched with five or six factors (5H, 6H); the latter media contained 5% FCS without (5H) or with (6H) thyrotropin (TSH). The follicles were converted into a confluent cell layer, which had similar DNA content irrespective of type of medium, after 4-6 days. Cells grown in EMEM or 5H established a transepithelial electrical resistance (R) of 200-500 omega.cm2 and was impermeable to [3H]inulin, indicating the formation of epithelial junctions. Addition of 6H to confluent cells initially cultured in EMEM or 5H caused a further increase of R, maximally to 1500 omega.cm2, along with a rise of the transepithelial potential difference; 6H promoted the monolayer formation of cells, increased the number of apical microvilli and reinforced the junctional distribution of actin, cadherin and ZO-1; 6H also enhanced the polarized secretion of [3H]leucine-labeled thyroglobulin into the apical medium. Cells from Graves' thyroid tissue established an epithelium on the filter with similar characteristics to that of normal thyrocytes; some platings contained in addition large numbers of HLA-DR positive cells with a dendritic shape. HLA-DR expression was generally absent in EMEM-or 5H-grown thyrocytes, but appeared in limited areas of the cell layer after 6H and was expressed by all epithelial cells after interferon-gamma stimulation for 48 h. We conclude that human thyrocytes form a tight and polarized epithelium when cultured on permeable filters. The polarized structure and function of the cells are positively regulated by TSH. The culture system may be useful in studies addressing the role of the epithelial phenotype (cell polarity and tight barrier) in normal thyroid function as well as in pathological processes in the thyroid, such as autoimmunity, cell transformation and tumor progression.

Cell Polarity↗

Monoclonal antibodies to the human TSH receptor: epitope mapping and binding to the native receptor on the basolateral plasma membrane of thyroid follicular cells.

We have characterized four murine monoclonal antibodies (mAbs) to the extracellular domain of the human TSH receptor (TSH-R.E), the target autoantigen of Graves' disease. Recombinant TSH-R.E used as immunogen, was produced in E. coli as a fusion protein with glutathione-S-transferase or in a baculovirus-insect cell system, as a non-fusion glycoprotein. To increase the epitope specificity of the mAbs, two different strains of mice (H-2(b) and H-2(d)) were immunized. The epitopes recognized by the mAbs were characterized by immunoblotting with various recombinant constructs of TSH-R.E and by binding to overlapping synthetic peptides of the receptor. The four IgG mAbs characterized recognized epitopes localized to different regions on the TSH-R.E; amino acids 22-35 (A1O and A11, both IgG2b from H-2(b) animals), amino acids 402-415 (A7, IgG2b from H-2(b) animals) and amino acids 147-228 (A9, IgG1 from H-2(d) animals). Immunolocalization studies showed that mAb A9 recognized TSH-R.E on unfixed cryostat sections, where binding was localized to the basolateral plasma membrane of thyroid follicular cells, suggesting that this antibody reacts with the native receptor on thyroid cells. The binding of the mAbs A7, A10 and A11 was also restricted to the basal surface of thyroid cells, but only after acetone fixation of the sections, implying that the epitopes recognized on the amino and carboxyl terminus of the extracellular region of the receptor are not accessible on the native molecule. None of the mAbs stimulated cyclic AMP responses in COS-7 cells transiently transfected with full-length functioning TSH-R.E, whilst weak inhibition of binding of radiolabelled TSH to porcine membranes in a radioreceptor assay was apparent with mAb A10 and A11, but only at high concentrations of IgG. The ability of mAb A9 to bind to the native receptor without stimulating activity or inhibition of TSH binding suggests that antibody can bind to the central region of the TSH-R.E without perturbing receptor function. The availability of mAbs that recognize epitopes on different regions of the extracellular domain of TSH-R will lead to a better understanding of the autoantigenic regions on TSH-R implicated in disease activity.

Amino Acid Sequence↗

Neurotoxicity of cysteine: interaction with glutamate.

L-Cysteine produces excitotoxic brain damage but its chemical structure differs from that of other excitotoxins. Although it is an NMDAmimetic, its mode of action is complex and may encompass antiexcitotoxic components. The purpose of the present study was to investigate whether cysteine kills neurons by potentiating the effects of glutamate and/or by releasing glutamate. In primary cultures of cortical neurons, 24 h of exposure to glutamate caused a concentration-dependent, dizocilpine-sensitive cell death as measured by release of lactate dehydrogenase. Cysteine was also toxic but higher concentrations were required. In addition, N-acetylcysteine produced mild toxicity at 1 mM. There was no general potentiation between either glutamate and cysteine or glutamate and N-acetylcysteine although some combinations acted synergistically. In no case did the thiols inhibit glutamate toxicity. The interaction between glutamate and cysteine toxicity was also assessed in the immature rat arcuate nucleus in vivo. When given at a dose (0.5 mg/g) that did not cause any toxicity per se, cysteine enhanced the toxicity of glutamate (0.3-0.8 mg/g). Cortical microdialysis was carried out in anesthetized rats (8-10 days old) administered a toxic dose of cysteine (1 mg/g). The levels of taurine were elevated 15-fold, phosphoethanolamine 3-fold and alanine 2-fold. Despite the observation that glutamine decreased markedly and rapidly, there was only a delayed doubling of glutamate concentrations. It is therefore unlikely that cysteine induces neurotoxicity by releasing glutamate. Taken together, the results suggest that there is a synergistic effect between cysteine and glutamate. Speculatively, this potentiation may be produced by reduction by cysteine of the redox site of the glutamate-activated NMDA receptor-ionophore complex.

Animals↗

Activated Ha-Ras but not TPA induces transcription through binding sites for activating transcription factor 3/Jun and a novel nuclear factor.

We report the identification of a 20-base pair sequence mediating induced transcription in response to an activated Ha-ras gene and epidermal growth factor (EGF) but not 12-O-tetradecanoylphorbol-13-acetate stimulation. This signal-specific nuclear target is present in the long terminal repeat of a mouse VL30 retrotransposon expressed in epidermis. Functional studies and in vitro binding analyses using cultured keratinocytes (Balb/MK) reveal that the response element is composed of two cooperating sequence motifs in juxtaposed position, both of which are targets for induced binding activity 1-2 h after EGF stimulation. Of many different activating transcription factor/cAMP-responsive element binding protein/activating protein 1 factors tested, one part of the sequence selectively binds endogenous proteins immunologically related to activating transcription factor 3 (ATF3) and Jun isotypes. The other sequence is a target for a nuclear factor showing binding specificity unrelated to factors known to mediate EGF- or ras-induced transcription as determined by its sequence specificity and by antibody experiments. This component has been characterized and partially purified by gel filtration chromatography and velocity centrifugation revealing a Stokes radius of 43.6 A and a sedimentation coefficient of 9.7 S in solution. Based on these parameters, a molecular mass of 178,000 Da was calculated. The results indicate that the specific binding of ATF3/Jun and a previously uncharacterized factor account for signal-specific transcription in response to EGF or an activated Ha-ras gene in a cell type in which the cooperative action of an activated Ha-ras gene and 12-O-tetradecanoylphorbol-13-acetate cause tumor growth.

3T3 Cells↗

FGF binding and FGF receptor activation by synthetic heparan-derived di- and trisaccharides.

Fibroblast growth factors (FGFs) require a polysaccharide cofactor, heparin or heparan sulfate (HS), for receptor binding and activation. To probe the molecular mechanism by which heparin or HS (heparin/HS) activates FGF, small nonsulfated oligosaccharides found within heparin/HS were assayed for activity. These synthetic and isomerically pure compounds can activate the FGF signaling pathway. The crystal structures of complexes between FGF and these heparin/HS oligosaccharides reveal several binding sites on FGF and constrain possible mechanisms by which heparin/HS can activate the FGF receptor. These studies establish a framework for the molecular design of compounds capable of modulating FGF activity.

Animals↗

Identification of a neutralizing epitope on an 82-kDa protein encoded by gene 3 of group C rotavirus.

A neutralizing monoclonal antibody (1A5) with hemagglutination inhibition activity was produced against a cultivable porcine group C rotavirus strain (strain AmC-1) and used to identify and map the functional topography of the protein involved in viral neutralization. The 1A5 mAb recognized an 82-kDa protein from infected cells as well as an equivalent in vitro-translated protein programmed with gene 3 of the AmC-1 strain. By employing a method called DNA amplification-restricted transcription-translation a series of C-terminal-truncated fragments of the 82-kDa protein was produced. Immunoprecipitation experiments show that 1A5 recognizes an epitope located on vp5, a tentative trypsin cleavage fragment of the 82-kDa protein. The functional and antigenic topography on the 82-kDa protein is discussed in relation to vp4 of group A rotavirus.

Animals↗

Amelogenin signal peptide mutation: correlation between mutations in the amelogenin gene (AMGX) and manifestations of X-linked amelogenesis imperfecta.

Formation of tooth enamel is a poorly understood biological process. In this study we describe a 9-bp deletion in exon 2 of the amelogenin gene (AMGX) causing X-linked hypoplastic amelogenesis imperfecta, a disease characterized by defective enamel. The mutation results in the loss of 3 amino acids and exchange of 1 in the signal peptide of the amelogenin protein. This deletion in the signal peptide probably interferes with translocation of the amelogenin protein during synthesis, resulting in the thin enamel observed in affected members of the family. We compare this mutation to a previously reported mutation in the amelogenin gene that causes a different disease phenotype. The study illustrates that molecular analysis can help explain the various manifestations of a tooth disorder and thereby provide insights into the mechanisms of tooth enamel formation.

Amelogenesis Imperfecta↗

Distribution and development of G alpha i-2 mRNA in the rat cerebral cortex investigated with in situ hybridization and RNAse protection assay.

The distribution of the G alpha i-2 mRNA was investigated with in situ hybridization on tissue sections of the rat cerebral cortex. A non-radioactive method based on digoxygenin labelled cRNA was used for in situ hybridization. The G alpha i-2 mRNA was shown to be present predominantly in large neuronal shaped cells in laminae II-III. The ontogenic development of the expression of G alpha i-2 mRNA in the rat cerebral cortex was quantified using a solution hybridization RNAse protection assay. The abundancy of G alpha i-2 mRNA was shown to increase significantly from embryonic day 16 to adult age. The amount of G alpha i-2 mRNA in adult cerebral cortex of the rat brain was 23 amol/micrograms RNA. The distribution and ontogenic development of G alpha i-2 mRNA are discussed.

Animals↗

Effects of epidermal growth factor and phorbol ester on thyroid epithelial integrity.

The effects of epidermal growth factor (EGF) and phorbol ester (tetra-O-decanoylphorbol-16-acetate; TPA) on thyroid epithelial integrity were studied in filter-cultured monolayers of porcine thyrocytes, which before experiments were growth-arrested and had a high transepithelial resistance (RTE > 6.10(3) omega.cm2) and polarized, thyroid-specific functions. Both EGF and TPA stimulated dose-dependently the cellular incorporation of [3H]thymidine, which maximally (at 10 ng/ml EGF for 48 h) corresponded to a 65% increase of the DNA content. The EGF-treated cells proliferated mainly within the original monolayer, which became folded due to the increased cell number; clusters of epithelial cells also assembled between the monolayer and the filter. Although the transepithelial potential difference was reduced, from 15-30 mV in controls to 2-10 mV, the epithelial barrier function was maintained (RTE 1-3.10(3) omega.cm2; impermeability to [3H]inulin). EGF did not change the ultrastructural polarity of the plasma membrane or the distinct distribution of ZO-1 and cadherin immunoreactivities to junctions, but cytoplasmic cadherin present in controls disappeared after EGF. In cultures acutely depleted of extracellular Ca2+ EGF pretreatment for 48 h antagonized the preventive effect of thyrotropin on paracellular leakage and loss of cell-cell adhesion. TPA (0.1 microM) induced a temporary barrier dysfunction (maximal after 24 h) accompanied by pronounced alterations of cell shape and actin-based cytoskeleton, dissociation of junctional cadherin, and shedding of cells into the apical medium. In long-term (2-5 days) TPA-treated cultures the epithelial morphotype and barrier function recovered. The combined stimulation with EGF and TPA caused a persistent derangement of the cell layer including attenuation of ZO-1 at cell-cell contacts, paracellular leakage of [3H]inulin, and cell detachment. We conclude that EGF is able to release porcine thyroid epithelial cells from contact inhibition of growth along with intact cell polarity and tight junctions. Yet, when acting together with phorbol ester EGF provokes a lasting morphological transformation. Impaired positive control of Ca(2+)-dependent cell-cell adhesion in EGF-treated cultures suggests a latent defect with possible transforming potential in the cadherin-based regulation of the junctional complex.

Animals↗

Transforming growth factor-beta promotes epidermal growth factor-induced thyroid cell migration and follicle neoformation in collagen gel separable from cell proliferation.

The regulation of growth and migration of thyroid follicular cells by epidermal growth factor (EGF) and transforming growth factor-beta (TGF-beta 1) were studied in primary cultures of porcine thyroid follicles embedded in collagen gel. Cultures were exposed to growth factors and [3H]thymidine (1 microCi/ml) for 3 days and then examined by light microscopic autoradiography. EGF at 1 ng/ml increased the [3H]thymidine labeling index from approximately 1% (control value) to 60% and stimulated fivefold the number of cells invading the collagen matrix. Intermediate responses were seen after treatment with 0.1 ng/ml of EGF. EGF-stimulated [3H]thymidine incorporation was reduced by TGF-beta 1 at concentrations above 0.1 ng/ml. In contrast, TGF-beta 1, which alone only had a minor stimulatory effect on cell motility, markedly promoted the migratory response to EGF (1 ng/ml). Thus, 0.1 ng/ml TGF-beta 1 doubled the fraction of migrating cells without changing the level of [3H]thymidine incorporation. Moreover, cell migration was still fourfold over control values in cultures exposed to 1.0 ng/ml EGF and 1.0 ng/ml TGF-beta 1, despite a strongly inhibited [3H]thymidine labeling. The number of microfollicles located peripherally to the mother follicles was increased synergistically by EGF and TGF-beta 1. The epithelium of mother follicles became grossly discontinuous in regions of intense cell migration induced by EGF and TGF-beta 1 in combination. In conclusion, TGF-beta 1 modulates the response of porcine thyrocytes to EGF in collagen gel cultures by promoting cell migration along with inhibition of [3H]thymidine incorporation. This suggests that EGF stimulates cell motility independent of the mitogenic signal. The persistent loss of epithelial integrity during enhanced cell migration indicates that mechanisms of intercellular adhesiveness are down-regulated by TGF-beta 1 and EGF in cooperation.

Animals↗

Pharmacokinetics and tissue distribution of cisplatin in nude mice: platinum levels and cisplatin-DNA adducts.

The pharmacokinetics of platinum (Pt) and cisplatin (CDDP)-DNA adducts were studied in nude mice after single-dose CDDP treatments. Whole blood, serum, kidney, lever, testis, brain, and tumor were collected at different intervals after injection of CDP at different dose levels. Pt was measured with flameless atomic absorption spectrometry (FAAS) or adsorptive voltammetry (AdV) and CDDP-DNA adducts with quantitative immunohistochemistry. The drug was immediately absorbed into the blood circulation (peak serum Pt levels were reached within 5 min) after i.p. CDDP administration, and distribution into most tissues also occurred rapidly (tissue Pt levels peaked at 15 min). With a sampling period of 7 days there was a biphasic elimination of Pt from blood, serum, and tissues. In the brain the pharmacokinetics differed with a gradual accumulation of Pt occurring during the 1st week. Formation of CDDP-DNA adducts in tissues was a slower process, with maximal levels being achieved at between 30 min and 4 h after drug administration, followed by a steady state lasting for at least 24 h. Each tissue type had its specific immunohistochemical staining pattern of adducts. With escalating CDDP doses there was a linear, or almost linear, increase in Pt concentrations and CDDP-DNA adduct levels in all sample types examined. These results suggest that a fair estimation of the amount of drug in tumor and normal tissues can be made from analysis of serum Pt at a fixed time point after a single dose of CDDP.

Animals↗

Pharmacodynamic effects of meropenem on gram-negative bacteria.

The in vitro initial killing and post-antibiotic effect (PAE) of meropenem on five gram-negative reference strains were evaluated by bioluminescence assay of bacterial adenosine triphosphate (ATP) and viable count. Morphology studies were performed in parallel. Meropenem showed concentration-dependent long (2-5 h) PAEs on Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Serratia marcescens when assayed by bioluminescence and induced spheroplasts at almost all concentrations. The bioluminescence PAEs reached a maximum response at 4 x MIC. These PAEs of meropenem on Escherichia coli, Klebsiella pneumoniae and Serratia marcescens were longer than corresponding PAEs of imipenem shown in previous studies. The higher affinity of meropenem than imipenem for PBP 3 might explain the longer PAEs obtained with meropenem. However, there was only a very short PAE, no PAE or even a negative PAE when viable count was used as the initial value for the PAE calculation. A strong initial decrease in viability but a less pronounced change in intracellular ATP was registered. Since this initial change in cell numbers is the initial value for the PAE calculation, the length of PAE was highly method dependent. In summary, a strong initial killing and no PAE were shown using viable count as the initial value for the PAE calculation, but a weak initial killing and long PAEs were shown when bioluminescence was used throughout the experiments.

Gram-Negative Bacteria↗

Control-related effective regrowth time and post-antibiotic effect of meropenem on gram-negative bacteria studied by bioluminescence and viable counts.

A study was performed to compare viable counts and bioluminescence for determining control related effective regrowth time (CERT) and postantibiotic effect (PAE) on Gram-negative bacteria after two hours of exposure to meropenem. There was a good correlation between bioluminescence and viable counts in determining the cell numbers in growing cultures of Escherichia coli. CERT was defined as the time required for the resumption of logarithmic growth and an increase of 1 log10 to occur over the pre-exposure inoculum in the test culture minus corresponding time for the control culture. PAE and CERT were studied on reference strains of Enterobacter cloacae, E. coli, Klebsiella pneumoniae and Pseudomonas aeruginosa. At 4 x MIC of meropenem the CERTs of these four Gram-negative strains were 4.1, 4.9, 4.2, and 3.6 h, respectively, when assayed by bioluminescence. Corresponding CERTs using viable counts were 4.2, 5.0, 5.1 and 3.8 h, respectively. In contrast to this good agreement between the methods in assessing CERT, the corresponding PAEs were highly method dependent. At 4 x MIC of meropenem the PAEs on E. cloacae, E. coli, K. pneumoniae and P. aeruginosa were 3.9, 4.8, 4.7, and 3.5 h, respectively, when assayed by bioluminescene. However, the corresponding and simultaneously determined viable count PAEs were -0.4, 0.5, -0.1, and 0.7 h, respectively. The poor correlation between these methods in assessing the PAE is caused by greater initial decrease in viability compared with the less prominent initial change in cell density as measured by bioluminescence.(ABSTRACT TRUNCATED AT 250 WORDS)

Colony Count, Microbial↗