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At least 649 records · Page 36Linked to original sources
PubMed1998

Alternative splicing of VWFA modules generates variants of type VI collagen alpha 3 chain with a distinctive expression pattern in embryonic chicken tissues and potentially different adhesive function.

Type VI collagen, a ubiquitous extracellular cell adhesion molecule, is formed by heterotrimeric monomers which associate into dimers and tetramers and assemble into larger oligomers constituting the 100 nm-long periodic microfilaments of connective tissues. One distinctive structural characteristic of type VI collagen is represented by an alpha 3 chain with a much larger molecular mass compared to the other two chains and with an extensive size heterogeneity, exemplified by the separation into up to five polypeptides in SDS-PAGE. There is evidence that the alpha 3(VI) mRNA can undergo alternative splicing of three VWFA modules at the 5'-end, potentially resulting in the expression of protein variants. Here we report that alternative splicing of alpha 3(VI) mRNA in chicken embryo did not result in the absolute predominance of a particular alpha 3(VI) form in any tissue; instead, the expression of variants including exons A9, A8 and A6 increased with age. In addition, these variants had a more restricted tissue distribution pattern compared to variants including only constitutive exons: A9+ were the rarest and were present almost exclusively in skin and skeletal muscle; A6+ were expressed in several of the examined tissues with local variations; A8+ had intermediate levels and were less widely distributed than A6+ variants. Quantitative densitometric scanning of immunoblots of type VI collagen purified from gizzard and stained with VWFA module-specific antibodies indicated that the polymorphic migration pattern of alpha 3(VI) polypeptides is contributed by concurrent or independent splicing of two exons (A8 and A6) and probably by processing and/or proteolysis at the N- and C-terminus. Three exon-specific recombinant polypeptides were examined in cell adhesion assays, and A6 appeared to be the most active, particularly at low substrate concentrations. The adhesion to the recombinant modules was not abrogated by EDTA nor by mAbs against the integrin beta 1 or alpha 2 subunits. Over all, these results suggest that the splicing of the alpha 3(VI) mRNA and the tissue distribution pattern of type VI collagen variants, apart from promoting cell adhesion to different extents, might also affect additional structural as well as functional properties of this molecule, including microfilament formation and interaction with other extracellular matrix molecules.

Alternative Splicing↗
PubMed2005

Long-term functional impairment of hemopoietic progenitor cells engineered to express the S1 catalytic subunit of pertussis toxin.

OBJECTIVE: A large body of data suggests that pertussis toxin (PTX)-sensitive G protein signals in mature and immature hemopoietic cells control their migration patterns in vitro and in vivo. These effects were derived after treatment of cells or animals with PTX. To circumvent several inherent problems of PTX holotoxin treatment, we expressed the S1 catalytic activity of PTX, thus blocking Gi protein signaling, in 32D murine myeloid progenitor cells and in primary human CD34+ cells, and studied its functional consequences. METHODS: S1 was expressed using viral vectors. Effects of Gi protein blockade on proliferation, migration, adhesion, and gene expression were tested in vitro. RESULTS: S1 expression was nontoxic for the cells; expression and function were stable long-term and not overridden by compensatory mechanisms. S1-transduced 32D cells and primary CD34+ cells migrated poorly and did not contract their cytoskeleton upon treatment with the chemoattractant stromal cell-derived factor -1 (SDF-1), similar to the phenotype induced by PTX treatment. Gene expression studies comparing S1-transduced and control 32D cells uncovered four genes, expression of which was regulated by Gi protein blockade. Of interest, although SDF-1 signaling was inhibited, comparison between SDF-1-treated and untreated cells suggests that SDF-1 stimulation does not depend on de novo gene expression in these cells. Furthermore, when injected into nonobese diabetic/severe combined immunodeficient mice, seeding of S1-expressing 32D cells to bone marrow was largely blocked. CONCLUSION: Expression of S1 is an effective approach for studying long-term functional consequences of Gi protein blockade in hemopoietic cells in vitro and in vivo.

Base Sequence↗
PubMed2001

Extrafollicular plasmablast B cells play a key role in carrying retroviral infection to peripheral organs.

B cells can either differentiate in germinal centers or in extrafollicular compartments of secondary lymphoid organs. Here we show the migration properties of B cells after differentiation in murine peripheral lymph node infected with mouse mammary tumor virus. Naive B cells become activated, infected, and carry integrated retroviral DNA sequences. After production of a retroviral superantigen, the infected B cells receive cognate T cell help and differentiate along the two main differentiation pathways analogous to classical Ag responses. The extrafollicular differentiation peaks on day 6 of mouse mammary tumor virus infection, and the follicular one becomes detectable after day 10. B cells participating in this immune response carry a retroviral DNA marker that can be detected by using semiquantitative PCR. We determined the migration patterns of B cells having taken part in the T cell-B cell interaction from the draining lymph node to different tissues. Waves of immigration and retention of infected cells in secondary lymphoid organs, mammary gland, salivary gland, skin, lung, and liver were observed correlating with the two peaks of B cell differentiation in the draining lymph node. Other organs revealed immigration of infected cells at later time points. The migration properties were correlated with a strong up-regulation of alpha(4)beta(1) integrin expression. These results show the migration properties of B cells during an immune response and demonstrate that a large proportion of extrafolliculary differentiating plasmablasts can escape local cell death and carry the retroviral infection to peripheral organs.

Animals↗
PubMed1977

Evaluation of the possible role of B cell receptors in the tendency of B cells to migrate into follicles in mice and chickens.

Chicken spleen and bursa cells were examined for the percentage of Fc receptor-bearing cells. Rosette formation was done with chicken 7S antibody-sensitized sheep erythrocytes and was inhibited by heat-aggregated chicken Ig. In the spleen, the percentage was found to increase with age to approximately 26% at 7 to 12 weeks. In contrast, only 3 to 5% of bursa cellss at this age demonstrated Fc receptors. Sleens from bursectomized chickens had 7--10% Fc receptor-bearing cells. In an attempt to determine a possible role of the C3 receptor on migration patterns, the effect of cobra venom factor (CVF) on the localization of transferred lymphoid cells was examined. Pretreatment of recipients with enough CVF to lower mean C3 levels to 11% of controls failed to affect follicular B cell localization in mice at either 24 or 48 h after transfer. Localization of thymus or bursa cells in chickens was similarly unaffected by CVF pretreatment. The possible roles of Fc and C3 receptors on migration of B lymphocytes into follicles and germinal centers were discussed.

Animals↗
PubMed1992

National-, regional- and urban-scale population deconcentration in West Germany.

"Internal migration patterns during the second half of the 1970s and the first half of the 1980s are evaluated at a regional scale intermediate to those utilized in previous core-to-periphery and urbanization-to-counterurbanization studies of West Germany. A spatial deconcentration of the West German population is evident in the form of redistribution down the metropolitan size hierarchy....A spatial deconcentration of manufacturing and service employment partially explains the net migration losses experienced by the Rhine-Ruhr and the Rhine-Main-Neckar [regions].... This study provides an alternative core-periphery delimitation scheme which can be applied to the metropolitan system in the western part of newly unified Germany."

Demography↗
PubMed2005

Plant-specific mitotic targeting of RanGAP requires a functional WPP domain.

The small GTPase Ran is involved in nucleocytoplasmic transport, spindle formation, nuclear envelope (NE) formation, and cell-cycle control. In vertebrates, these functions are controlled by a three-dimensional gradient of Ran-GTP to Ran-GDP, established by the spatial separation of Ran GTPase-activating protein (RanGAP) and the Ran guanine nucleotide exchange factor RCC1. While this spatial separation is established by the NE during interphase, it is orchestrated during mitosis by association of RCC1 with the chromosomes and RanGAP with the spindle and kinetochores. SUMOylation of vertebrate RanGAP1 is required for NE, spindle, and centromere association. Arabidopsis RanGAP1 (AtRanGAP1) lacks the SUMOylated C-terminal domain of vertebrate RanGAP, but contains a plant-specific N-terminal domain (WPP domain), which is necessary and sufficient for its targeting to the NE in interphase. Here we show that the human and plant RanGAP-targeting domains are kingdom specific. AtRanGAP1 has a mitotic trafficking pattern uniquely different from that of vertebrate RanGAP, which includes targeting to the outward-growing rim of the cell plate. The WPP domain is necessary and sufficient for this targeting. Point mutations in conserved residues of the WPP domain also abolish targeting to the nuclear rim and the cell plate, suggesting that the same mechanism is involved in both targeting events. These results indicate that plant and animal RanGAPs undergo different migration patterns during cell division, which require their kingdom-specific targeting domains.

Amino Acid Motifs↗
PubMed1983

Transport of immune complexes from the subcapsular sinus to lymph node follicles on the surface of nonphagocytic cells, including cells with dendritic morphology.

The objective of the present study was to investigate the mechanism of antigen migration from the site of initial localization in the lymph node subcapsular sinus (SS) to regions of follicular retention in the cortex. The migration of horseradish peroxidase (HRP), used as a histochemically identifiable antigen, was followed by light and electron microscopy in C3H mouse popliteal lymph nodes obtained 1, 5, 15, and 30 min, and 5 and 24 hr after hindfoot pad injection of HRP. The observations showed that as early as 1 min after HRP injection, localization of antigen occurred at distinct sites in the SS and subjacent areas of the cortex on the afferent side. At these sites, between 1 min and 24 hr, the antigen formed light microscopically identifiable trails, which reached progressively deeper into the cortex with time toward individual follicular regions. By 24 hr this apparent migration of antigen was complete, and HRP was localized in follicles. This migration pattern did not occur on the efferent sides of lymph nodes, and it was dependent on the systemic presence of specific antibodies since it was observable only in passively immunized but not in nonimmune mice. Temporary retention of antigen by typical macrophages was also observed in the SS on the efferent side. This was minimal in nonimmune mice and was significantly enhanced in passively immunized mice. Electron microscopy indicated that the apparent migration of immune complexes was mediated by a group of cells observed in the migration path that had immune complexes sequestered on their surface or in plasma membrane infoldings. These antigen transporting cells (ATC) were relatively large nonphagocytic cells, with lobated or irregular euchromatic nuclei and cell processes of various complexity. ATC observed in or near the SS appeared to be less differentiated, were monocyte-like, and resembled non-Birbeck granule-containing Langerhans cell precursors or veiled cells. Others, located deeper in the cortex, appeared more differentiated, interdigitated with antigen-retaining dendritic cells, and shared morphologic characteristics with follicular dendritic cells (FDC). The results support the concepts that immune complexes are trapped in the SS and are transported by a group of non-phagocytic cells, other than lymphocytes, to follicular regions. The mechanism of transport may involve the migration of ATC with a concomitant maturation into FDC, or by a mechanism of ATC to FDC transport utilizing dendritic cell processes and membrane fluidity, or by a combination of the two mechanisms.

Animals↗
PubMed1997

Chlamydia psittaci IncA is phosphorylated by the host cell and is exposed on the cytoplasmic face of the developing inclusion.

Chlamydiae are obligate intracellular bacteria that replicate within a non-acidified vacuole called an inclusion. Chlamydia psittaci (strain GPIC) produces a 39 kDa protein (IncA) that is localized to the inclusion membrane. While IncA is present as a single 39 kDa species in purified reticulate bodies, two additional higher M(r) forms are found in C. psittaci-infected cells. This finding suggested that IncA may be post-translationally modified in the host cell. Here we present evidence that IncA is a serine/threonine phosphoprotein that is phosphorylated by host cell enzymes. This conclusion is supported by the following experimental findings: (i) treatment of infected cells with inhibitors of host cell phosphatases or kinases altered the electrophoretic migration pattern of IncA; (ii) treatment with calf intestinal alkaline phosphatase eliminated the multiple-banding pattern of IncA, leaving only the protein band with the lowest relative molecular weight; and (iii) radioimmunoprecipitation of lysates of [32P]-orthophosphate-labelled infected HeLa cells with anti-IncA antisera demonstrated that the two highest M(r) IncA bands were phosphorylated. A vaccinia-virus recombinant expressing incA was used to determine if HeLa cells can phosphorylate IncA in the absence of a chlamydial background. IncA in lysates of these cells migrated identically to that seen in C. psittaci-infected cells, indicating the host cell was responsible for the phosphorylation of the protein. Microinjection of fluorescently labelled anti-IncA antibodies into C. psittaci-infected HeLa cells resulted in immunostaining of the outer face of the inclusion membrane. Collectively, these results demonstrate that IncA is phosphorylated by the host cell, and regions of IncA are exposed at the cytoplasmic face of the inclusion.

Animals↗
PubMed2005

In vivo tracking for cell therapies.

The success of a particular cellular therapy regime requires the therapeutic agent to migrate expeditiously to the intended target in sufficient numbers and to provoke a desirable response. There are many variables associated with the production, administration and host that need to be investigated to maximize the resulting therapeutic benefit. The large number of factors which may contribute to, or detract from, treatment efficacy can make therapy optimization an arduous procedure. Direct visualization of in vivo migration patterns using nuclear medicine techniques greatly assists the appraisal of the multitude of variables. Conventional radionuclide cell labeling is a proven, simple and sensitive technique which can provide whole body biodistribution information. Labeling with a PET isotope offers greater sensitivity, much improved 3-dimensional resolution and quantification. In general, current efforts are increasingly concentrating on this technology. Imaging studies can supply definitive evidence of successful targeting and allow quantification of the degree of migration to a particular site. Incorporating tracking studies into clinical trials of cell-based therapy at the earliest stage can provide proof of mechanism of the therapy and permit evaluation of the many contributory variables, even on a patient-by-patient basis.

Animals↗
PubMed1977

Development of of macrophage migration inhibition in rabbits infected with virulent Treponema pallidum.

Peritoneal exudate cells from rabbits infected with Treponema pallidum Nichols were used as indicators of macrophage migration inhibitory factor activity. Between 3 and 15 weeks after infection, the migration of peritoneal exudate cells was inhibited in the presence of 3 to 25 microgram of T. phagedenis biovar Reiter protein per ml. Before this period, the migration patterns of peritoneal exudate cells from infected animals were uninhibited and similar to those from noninfected control rabbits. These observations were correlated with the development of active cell-mediated immunity during experimental T. pallidum infection.

Animals↗
PubMed1986

Biochemical and antigenic characterization of feline herpesvirus-1-like isolates from dogs.

The DNA and polypeptide patterns of feline herpesvirus-1 (FHV-1), a virus usually associated with feline respiratory infections, were compared to those of five herpesvirus isolates from dogs. These canine isolates had been shown to be antigenically similar to FHV-1 by cross neutralization tests. DNA from FHV-1 (C-27 strain) and each canine isolate was digested with either Bam HI, Eco R 1 or Sal I and analyzed on 0.8 per cent agarose gels. The restriction digest patterns of the canine isolates were nearly identical to C-27 for all three restriction enzymes. Interestingly, all of the canine isolates showed a small extension of the largest Bam HI fragment (14.5 kb) that was not present in the C-27 strain. Bam HI digested FHV-1 DNA from clinical cases in cats had digest patterns that were very similar to the canine isolates and also showed an extension of the 14.5 kb fragment. Southern blotting experiments revealed that DNA from the canine isolates has extensive homology to C-27 DNA. SDS-PAGE analysis of radiolabeled polypeptides from C-27 and the canine isolates showed identical virion-associated polypeptide profiles. In addition, a goat anti-FHV-1 antiserum precipitated three glycoprotein antigens from the canine isolates with migration patterns that were identical to the three major antigenic glycoproteins found on C-27. Hind III and Eco R1 digestion patterns of canine herpesvirus DNA showed no similarity to C-27 DNA. In addition, canine herpesvirus DNA had no homology to C-27 DNA under the stringent conditions used.

Animals↗
PubMed1981

Migration of mouse lymphocytes in vitro. I. Normal lymph node lymphocytes.

Normal unstimulated mouse lymph node lymphocytes (LNLs) migrated into filters in a gradient of normal mouse serum (NMS), heat-inactivated mouse serum (HI-MS), or zymosan-activated mouse serum (ZAS). Blind well chemotaxis chambers with 5-micrometer pore size cellulose nitrate membranes were used. Migration was assessed both by the leading front technique and the mean aggregate number. A concentration of 2.5 x 10(6) LNLs/ml or greater was needed to detect migration. Migration of LNLs to 1% NMS was time dependent and was inhibited by cytochalasin B. Comparison of the migration patterns of LNLs, neutrophils, and macrophages revealed that all cell types were responsive to NMS. LNLs responded as well to HI-MS as they did to NMS, neutrophils responded less well to HI-MS than to MMS, and macrophages did not respond to HI-MS. The LNL response to ZAS was significantly greater than the response to NMS to HI-MS and neutrophils and macrophages also responded strongly to ZAS. The migration of LNLs from various mouse strains to NMS revealed that the LNLs from different mouse strains possess varying degree of motility. The factor in mouse serum which induced migration was not strain specific. The LNLs from peripheral (inguinal, axillary, and brachial) nodes demonstrated greater motility in response to NMS than mesenteric LNLs. Using the checkerboard assay to discriminate chemotaxis from chemokinesis, mouse serum appeared to be solely chemokinetic when the leading front technique was used. However, using the mean aggregate number technique, mouse serum was determined to be both chemokinetic acid chemotactic for LNLs. The results indicate that the method can be reliably used to study those factors which influence the motility of normal or altered populations of lymphocytes.

Animals↗
PubMed1990

C4 reference typing report.

Human C4 is most polymorphic at the protein level, distinction between allotypes of the C4A and C4B proteins resting on electrophoretic migration patterns and difference in hemolytic activity. The aim of the C4 reference typing has been the definition of reference variants, the assignment of rare variants, and the investigation of duplicated, deleted, or non-expressed and hybrid genes. Samples from 136 individuals, predominantly with known segregation, from 16 laboratories were investigated by standard electrophoretic techniques, for their relative hemolytic activity, reactivity with monoclonal antibodies and Rg/Ch reagents, alpha-, and beta-chain types, relative electrophoretic migration distance, as well as the C4/21-OH-TaqI RFLPs. The results were evaluated in three groups; they consisted in the definition of the eight most common C4 alleles, and the ten Rg/Ch standard phenotypes in group I. In group II twelve C4A and fourteen C4B duplications among 96 complotypes, as well as eighteen deleted/non-expressed C4A and twenty-two C4B alleles, and hybrid alleles were seen by correlation of lytic activity, electrophoretic mobility, and monoclonal and/or Rg/Ch reactivity. Group III consisted of the newly defined allotypes A 8, A 7, A 58, A 55, A 45, B 45, B 35, and B 22, furthermore of alleles subdividing the A 1/A 91, and the B 13/B 12/B 11 regions. The reference typing has allowed reclassification of the majority of described C4 allotypes and resulted in a revision of the C4 nomenclature.

Blood Grouping and Crossmatching↗
PubMed1975

Quantitative studies on Heterakis gallinarum infections in the common fowl, Gallus gallus L.

The fertility, mortality, and migration patterns of Hetarakis gallinarum were studied in chickens with concomitant Parahistomonas wenrichi infections. H. gallinarum females were found to produce approximately 936 ova per day, when 50 days of age, and a total of 34,000 to 86,000 ova in a lifetime. There was no evidence of differential mortality between the sexes, nor of a preference for either the left or the right caecal organ of chickens. Both male and female worms are capable of migrating between caeca, and are expecially prone to do so when in the absence of individuals of the opposite sex.

Animals↗
PubMed2006

Definitive N-terminal protein sequence and further characterization of the novel apolipoprotein A5 in human serum.

BACKGROUND: Apolipoprotein A5 (ApoA5) originally gained attention as a regulator of serum triglyceride concentrations through transgenic mouse studies. Our group recently developed the first assay to quantify serum ApoA5 protein concentrations and demonstrated that they are increased by administration of a potent peroxisome proliferator-activated receptor-alpha agonist. METHODS: To better characterize the circulating ApoA5, the protein was purified from human serum, and a definitive N-terminal protein sequence was obtained. In light of previous observations that ApoA5 was present in VLDL and not LDL, plasma infranatant and intermediate-density lipoprotein (IDL) were analyzed for ApoA5. Because the mature protein contains a single unpaired cysteine, ApoA5 in human serum was immunoprecipitated, and its migration pattern was examined via Western blotting under reducing and nonreducing conditions to determine whether the protein circulates as a disulfide-linked homodimer or heterodimer. RESULTS: Definitive N-terminal protein sequences obtained from ApoA5 purified from human serum indicated that cleavage of the signal peptide occurs in vivo at the predicted site. We found ApoA5 in VLDL, HDL, and chylomicrons but not in LDL, IDL, or plasma infranatant. Under both reducing and nonreducing conditions, ApoA5 migrated mainly as a single band with a relative molecular mass (Mr) of approximately 39,000, indicating that the protein exists in serum as a monomer and not as a disulfide-linked homodimer or heterodimer. CONCLUSIONS: Our data help characterize ApoA5 by defining its lipoprotein particle distribution, by determining its N-terminal protein sequence, and by demonstrating that the mature protein circulates mainly as a monomer and not as a disulfide-linked homodimer or heterodimer.

Amino Acid Sequence↗
PubMed1982

Patterns of drug use among secondary school children in post-revolutionary Iran.

A sample survey of 712 Iranian youths aged 14 - 18 years, attending secondary schools in the city of Isfahan, indicated that 11% had had experience of drug abuse. The most common pattern was the experimental use of opium, with a minority of users having also used hashish or heroin. No other drugs were reported, but a significant association between the use of opium and of cigarettes and, to a lesser extent, alcohol was observed. However, given a relatively early peak in initiation to opium smoking, it seems that the initiation to the use of cigarettes and alcohol is contemporary with, rather than preceding the initiation to opium. Drug migration patterns described in Western samples and in some areas of South East Asia are not applicable to more traditional societies.

Adolescent↗
PubMed1976

Synthesis of the acid-soluble proteins in early cleaving embryos of the sea urchin. Cyclic synthesis of histones.

Synthesis of the acid-soluble proteins in the early cleavage stage of the sea urichin, Hemicentrotus pulcherrimus, was investigated. As detected by the incorporation of lysine, the acid-soluble proteins were synthesized periodically even before the first cleavage, differing from the pattern of incorporation of tryptophan into the fraction. Cyclic synthesis occurred almost in parallel with DNA synthesis. However, the phase and periodicity of cyclic synthesis of the acid-soluble protein fraction were quite different from those found in the hot TCA-insoluble (acid-insoluble) protein fraction. The acid-soluble proteins were adsorbed on cation exchange resin, Amberlite CG-50, and gave an elution profile similar to that found for calf thymus histones. The migration pattern of these proteins on acrylamide gel also resembled that of histones.

Animals↗
PubMed2006

Rural health's demographic destiny.

Demography is the study of the size and composition of populations. Populations change size through births, deaths and net-migration. Over time, mortality, fertility and migration patterns create populations that may be large or small, young or old, growing or declining. Rural and remote Australia has a unique demography that determines its health problems and health service needs. The tendency of young adults to leave rural and remote areas for cities means that they leave behind communities which are, on average, older than those found in the cities. Rural and remote women have slightly more children at significantly younger ages, but because of out-migration, the actual number of babies born outside of the cities is smaller than would be expected. Most rural and remote areas already have a high proportion of their population over 65 years old. Many communities with an older population are declining in absolute numbers but the need for health services may be greater than required for smaller, younger communities. In contrast to the trends in total population, the rural and remote Aboriginal and Torres Strait Islander population is growing rapidly. This is the result of a higher proportion of young people, higher fertility rates and lower rates of moving to cities. The health characteristics of rural and remote Australia increasingly reflects the higher morbidity of Indigenous and older people. Responding to this demographic destiny is the present and future challenge.

Adolescent↗