bluuebunny/crossref_metadata_2025 huggingface dataset:
Nuclear and cell membrane effects contribute independently to the induction of apoptosis in human cells exposed to UVB radiation
Authors: Kulms Dagmar , Pöppelmann Birgit , Yarosh Daniel , Luger Thomas A. , Krutmann Jean , Schwarz Thomas
Published: July 2002

UVB-induced DNA damage is a crucial event in UVB-mediated apoptosis. On the other hand, UVB directly activates death receptors on the cell surface including CD95, implying that UVB-induced apoptosis can be initiated at the cell membrane through death receptor clustering. This study was performed to measure the relative contribution of nuclear and membrane effects in UVB-induced apoptosis of the human epithelial cell line HeLa. UVB-mediated DNA damage can be reduced by treating cells with liposomes containing the repair enzyme photolyase followed by exposure to photoreactivating light. Addition of photolyase followed by photoreactivation after UVB reduced the apoptosis rate significantly, whereas empty liposomes had no effect. Likewise, photoreactivating treatment did not affect apoptosis induced by the ligand of CD95, CD95L. UVB exposure at 4°C, which prevents CD95 clustering, also reduced the apoptosis rate, but to a lesser extent. When cells were exposed to UVB at 4°C and treated with photolyase plus photoreactivating light, UVB-induced apoptosis was almost completely prevented. Inhibition of caspase-3, a downstream protease in the CD95 signaling pathway, blocked both CD95L and UVB-induced apoptosis, whereas blockage of caspase-8, the most proximal caspase, inhibited CD95L-mediated apoptosis completely, but UVB-induced apoptosis only partially. Although according to these data nuclear effects seem to be slightly more effective in mediating UVB-induced apoptosis than membrane events, both are necessary for the complete apoptotic response. Thus, this study shows that nuclear and membrane effects are not mutually exclusive and that both components contribute independently to a complete response to UVB.
Discovery of virulence genes of
Legionella pneumophila
by using signature tagged mutagenesis in a guinea pig pneumonia model
Authors: Edelstein Paul H. , Edelstein Martha A. C. , Higa Futoshi , Falkow Stanley
Published: July 2002

Legionella pneumophila
is the cause of Legionnaires’ disease, which is a form of potentially fatal pneumonia. To identify genes required for virulence of the bacterium, a library of 1,386
L. pneumophila
signature tagged transposon mutants was studied for guinea pig virulence. The mutants were screened in pools of 96 each in a guinea pig model of
L. pneumophila
pneumonia. Sixteen unique mutant clones were determined to have attenuated virulence after being screened twice in the animal model. All 16 mutants failed to multiply in both lungs and spleens. Four of the sixteen had no apparent defect for intracellular multiplication in macrophages. Partial DNA sequences of the interrupted genes adjacent to the transposon insertions showed that six of them had mutations in five known
L. pneumophila
virulence genes:
dotB
,
dotF/icmG
,
dotO/icmB
,
icmX
, and
proA
. Three of the sequenced clones contained mutations in genes without known homology to other published bacterial genes, and seven clones appeared to be homologous to five different known bacterial genes but are still being characterized. With this methodology, we demonstrate the existence of
L. pneumophila
genes responsible for non-macrophage-related virulence. The discovery of
L. pneumophila
virulence genes indicates the utility of the signature tagged mutagenesis technique for pulmonary pathogens.
Development of gene-switch transgenic mice that inducibly express transforming growth factor β1 in the epidermis
Authors: Wang Xiao-Jing , Liefer Kristin M. , Tsai Sophia , O’Malley Bert W. , Roop Dennis R.
Published: July 2002

Previous attempts to establish transgenic mouse models to study the functions of transforming growth factor β1 (TGFβ1) in the skin revealed controversial roles for TGFβ1 in epidermal growth (inhibition vs. stimulation) and resulted in neonatal lethality in one instance. To establish a viable transgenic model for studying functions of TGFβ1 in the skin, we have now developed transgenic mice, which allow focal induction of the TGFβ1 transgene in the epidermis at different expression levels and at different developmental stages. This system, termed “gene-switch,” consists of two transgenic lines. The mouse loricrin vector targets the GLVPc transactivator (a fusion molecule of the truncated progesterone receptor and the GAL4 DNA binding domain), and a thymidine kinase promoter drives the TGFβ1 target gene with GAL4 binding sites upstream of the promoter. These two transgenic lines were mated to generate bigenic mice, and TGFβ1 transgene expression was controlled by topical application of an antiprogestin. On epidermal-specific induction of the TGFβ1 transgene, the BrdUrd labeling index in the transgenic epidermis decreased 6-fold compared with controls. Induction of the TGFβ1 transgene expression also caused epidermal resistance to phorbol 12-myristate 13-acetate-induced hyperplasia, with a reduction in both epidermal thickness and BrdUrd labeling compared with those in controls. In addition, TGFβ1 transgene expression induced an increase in angiogenesis in the dermis. Given that the TGFβ1 transgene can affect both the epidermis and dermis, this transgenic model will provide a useful tool for studying roles of TGFβ1 in wound-healing and skin carcinogenesis in the future.
Mammalian ELAV-like neuronal RNA-binding proteins HuB and HuC promote neuronal development in both the central and the peripheral nervous systems
Authors: Akamatsu Wado , Okano Hirotaka J. , Osumi Noriko , Inoue Takayoshi , Nakamura Shun , Sakakibara Shin-Ichi , Miura Masayuki , Matsuo Nobutake , Darnell Robert B. , Okano Hideyuki
Published: July 2002

Hu proteins are mammalian embryonic lethal abnormal visual system (ELAV)-like neuronal RNA-binding proteins that contain three RNA recognition motifs. Although
Drosophila
ELAV is required for the correct differentiation and survival of neurons, the roles played by the Hu genes in the mammalian nervous system remain largely unknown. To explore the
in vivo
functions of mouse Hu proteins, we overexpressed them in rat pheochromocytoma PC12 cells, where they induced neuronal phenotype in the absence of nerve growth factor. We have characterized the functions of various forms of mHuB and mHuC bearing point mutations or deletions. Mutants of mHuC that had amino acid exchanges in the RNP1 domain of the first or second RNA recognition motifs (RRMs) lost biologic activity as well as RNA-binding activity. In addition, the mutants containing only the third RRM failed to induce the neuronal phenotype in PC12 cells and inhibited the biologic activity of cotransfected wild-type mHuB and mHuC, thus acting as a dominant-negative form. However, these mutants could not suppress the nerve growth factor-induced differentiation of PC12 cells. Further, we misexpressed wild-type and dominant-negative Hu in E9.5 mouse embryos, by using electroporation into the neural tube at the level of the rhombencephalon. mHuB and mHuC induced the ectopic expression of neuronal markers, whereas the dominant-negative forms of mHuB and mHuC suppressed the differentiation of central nervous system motor neurons. From these results, we suggest that Hu proteins are required for neuronal differentiation in the mammalian nervous system.
Inhibition of nitric-oxide synthase 2 by aminoguanidine provides neuroprotection of retinal ganglion cells in a rat model of chronic glaucoma
Authors: Neufeld Arthur H. , Sawada Akira , Becker Bernard
Published: July 2002

Glaucoma is an optic neuropathy with cupping of the optic disk, degeneration of retinal ganglion cells, and characteristic visual field loss. Because elevated intraocular pressure (IOP) is a major risk factor for progression of glaucoma, treatment has been based on lowering IOP. We previously demonstrated inducible nitric-oxide synthase (NOS-2) in the optic nerve heads from human glaucomatous eyes and from rat eyes with chronic, moderately elevated IOP. Using this rat model of unilateral glaucoma, we treated a group of animals for 6 months with aminoguanidine, a relatively specific inhibitor of NOS-2, and compared them with an untreated group. At 6 months, untreated animals had pallor and cupping of the optic disks in the eyes with elevated IOP. Eyes of aminoguanidine-treated animals with similar elevations of IOP appeared normal. We quantitated retinal ganglion cell loss by retrograde labeling with Fluoro-Gold. When compared with their contralateral control eyes with normal IOP, eyes with elevated IOP in the untreated group lost 36% of their retinal ganglion cells; the eyes with similarly elevated IOP in the aminoguanidine-treated group lost less than 10% of their retinal ganglion cells. Pharmacological neuroprotection by inhibition of NOS-2 may prove useful for the treatment of patients with glaucoma.
Genetic alteration of phospholipase C β3 expression modulates behavioral and cellular responses to μ opioids
Authors: Xie Wei , Samoriski Gary M. , McLaughlin Jay P. , Romoser Valerie A. , Smrcka Alan , Hinkle Patricia M. , Bidlack Jean M. , Gross Robert A. , Jiang Huiping , Wu Dianqing
Published: July 2002

Morphine and other μ opioids regulate a number of intracellular signaling pathways, including the one mediated by phospholipase C (PLC). By studying PLC β3-deficient mice, we have established a strong link between PLC and μ opioid-mediated responses at both the behavioral and cellular levels. Mice lacking PLC β3, when compared with the wild type, exhibited up to a 10-fold decrease in the ED
50
value for morphine in producing antinociception. The reduced ED
50
value was unlikely a result of changes in opioid receptor number or affinity because no differences were found in whole-brain
B
max
and
K
d
values for μ, κ, and δ opioid receptors between wild-type and PLC β3-null mice. We also found that opioid regulation of voltage-sensitive Ca
2+
channels in primary sensory neurons (dorsal root ganglion) was different between the two genotypes. Consistent with the behavioral findings, the specific μ agonist [
d
-Ala
2
,(Me)Phe
4
,Gly(ol)
5
]enkephalin (DAMGO) induced a greater whole-cell current reduction in a greater proportion of neurons isolated from the PLC β3-null mice than from the wild type. In addition, reconstitution of recombinant PLC protein back into PLC β3-deficient dorsal root ganglion neurons reduced DAMGO responses to those of wild-type neurons. In neurons of both genotypes, activation of protein kinase C with phorbol esters markedly reduced DAMGO-mediated Ca
2+
current reduction. These data demonstrate that PLC β3 constitutes a significant pathway involved in negative modulation of μ opioid responses, perhaps via protein kinase C, and suggests the possibility that differences in opioid sensitivity among individuals could be, in part, because of genetic factors.
Chaos, but in voting and apportionments?
Authors: Saari Donald G.
Published: July 2002

Mathematical chaos and related concepts are
used to explain and resolve issues ranging from voting paradoxes to the
apportioning of congressional seats.
The 28–111 disulfide bond constrains the α-lactalbumin molten globule and weakens its cooperativity of folding
Authors: Luo Yongzhang , Baldwin Robert L.
Published: July 2002

Our aim is to determine whether the disulfide bonds of α-lactalbumin account for the lack of cooperative folding behavior reported for some molten globule variants, in contrast to the highly cooperative folding reported for the pH 4 molten globule of apomyoglobin. Two different α-lactalbumin genetic constructs are studied: [28–111], which has a single disulfide bond connecting two segments of the α-helix domain, and [all-Ala], which has no disulfide bonds. The superposition test used earlier to probe for cooperative folding of the apomyoglobin molten globule is used to determine whether there is an important difference in folding cooperativity between the molten globules of [28–111] and [all-Ala]. The [all-Ala] construct behaves in the same manner as the apomyoglobin molten globule: its folding satisfies the superposition test in the three sets of anion conditions studied, and anions stabilize it against urea unfolding. The [28–111] construct behaves differently in both respects: the folding of its molten globule does not satisfy the superposition test in two of the three sets of anion conditions, and anions barely affect its stability. The 28–111 disulfide bond stabilizes the molten globule substantially, as expected from earlier work. Comparison of the unfolding transition curves monitored by circular dichroism also demonstrates that [28–111] folds in a less cooperative manner than [all-Ala]: the unfolding curve of [28–111] is significantly broader. Moreover, the unfolding curves indicate that [28–111] has a lower helix content than [all-Ala]. Consequently, the 28–111 bond constrains the folding behavior of the molten globule and weakens its cooperativity of folding.
Structural features of the γ subunit of the
Escherichia coli
F
1
ATPase revealed by a 4.4-Å resolution map obtained by x-ray crystallography
Authors: Hausrath Andrew C. , Grüber Gerhard , Matthews Brian W. , Capaldi Roderick A.
Published: July 2002

The F
1
part of the F
1
F
O
ATP synthase from
Escherichia coli
has been crystallized and its structure determined to 4.4-Å resolution by using molecular replacement based on the structure of the beef-heart mitochondrial enzyme. The bacterial F
1
consists of five subunits with stoichiometry α
3
, β
3
, γ, δ, and ɛ. δ was removed before crystallization. In agreement with the structure of the beef-heart mitochondrial enzyme, although not that from rat liver, the present study suggests that the α and β subunits are arranged in a hexagonal barrel but depart from exact 3-fold symmetry. In the structures of both beef heart and rat-liver mitochondrial F
1
, less than half of the structure of the γ subunit was seen because of presumed disorder in the crystals. The present electron-density map includes a number of rod-shaped features which appear to correspond to additional α-helical regions within the γ subunit. These suggest that the γ subunit traverses the full length of the stalk that links the F
1
and F
O
parts and makes significant contacts with the
c
subunit ring of F
O
.
Recruitment of SMRT/N-CoR-mSin3A-HDAC-repressing complexes is not a general mechanism for BTB/POZ transcriptional repressors: The case of HIC-1 and γFBP-B
Authors: Deltour Sophie , Guerardel Cateline , Leprince Dominique
Published: July 2002

Hypermethylated in cancer (HIC-1), a new candidate tumor suppressor gene located in 17p13.3, encodes a protein with five C
2
H
2
zinc fingers and an N-terminal broad complex, tramtrack, and bric à brac/poxviruses and zinc-finger (BTB/POZ) domain found in actin binding proteins or transcriptional regulators involved in chromatin modeling. In the human B cell lymphoma (BCL-6) and promyelocityc leukemia (PLZF) oncoproteins, this domain mediates transcriptional repression through its ability to recruit a silencing mediator of retinoid and thyroid hormone receptor (SMRT)/nuclear receptor corepressor (N-CoR)-mSin3A-histone deacetylase (HDAC) complex, a mechanism shared with numerous transcription factors. HIC-1 appears unique because it contains a 13-aa insertion acquired late in evolution, because it is not found in its avian homologue, γF1-binding protein isoform B (γFBP-B), a transcriptional repressor of the γF-crystallin gene. This insertion, located in a conserved region involved in the dimerization and scaffolding of the BTB/POZ domain, mainly affects slightly the ability of the HIC-1 and γFBP-B BTB/POZ domains to homo- and heterodimerize
in vivo,
as shown by mammalian two-hybrid experiments. Both the HIC-1 and γFBP-B BTB/POZ domains behave as autonomous transcriptional repression domains. However, in striking contrast with BCL-6 and PLZF, both HIC-1 and γFBP-B similarly fail to interact with members of the HDAC complexes (SMRT/N-CoR, mSin3A or HDAC-1)
in vivo
and
in vitro
. In addition, a general and specific inhibitor of HDACs, trichostatin A, did not alleviate the HIC-1- and γFBP-B-mediated transcriptional repression, as previously shown for BCL-6. Taken together, our studies show that the recruitment onto target promoters of an HDAC complex is not a general property of transcriptional repressors containing a conserved BTB/POZ domain.
Cortical bitufted, horizontal, and Martinotti cells preferentially express and secrete reelin into perineuronal nets, nonsynaptically modulating gene expression
Authors: Pesold Christine , Liu Wen Sheng , Guidotti Alessandro , Costa Erminio , Caruncho Hector J.
Published: July 2002

Reelin (Reln) is a protein with some structural analogies with other extracellular matrix proteins that functions in the regulation of neuronal migration during the development of cortical laminated structures. In the cortex of adult animals, Reln is expressed primarily in γ-aminobutyric acid (GABA)ergic neurons and is secreted into perineuronal nets. However, only 50–60% of GABAergic interneurons express Reln. We have characterized this subpopulation of cortical GABAergic neurons that expresses Reln by using two strategies: (
i
) a double immunolabeling procedure to determine the colocalization of Reln with neuropeptides and Ca
2+
-binding proteins and (
ii
) a combination of Golgi staining and Reln immunolabeling to determine the morphology of the rat cortical cells that store Reln. Many interneurons that express Neuropeptide Y (NPY) or somatostatin (but none of those that express parvalbumin) are Reln-immunopositive. A small population of calbindin-positive interneurons and very few calretinin-positive cells express Reln immunopositivity. Golgi staining revealed that layer I horizontal cells, layer II–V bitufted neurons, and some deep cortical layer Martinotti cells express Reln. Basket and chandelier cells are often immunopositive to parvalbumin, but never to Reln. Although Reln is secreted by GABAergic neurons, its target are not the GABA receptors, but rather may be extrasynaptically located in perineuronal nets and concerned with the modulation of neuronal plasticity. Dab1, the target adapter protein that presumably mediates transcription regulation via the extrasynaptic actions of Reln, is expressed predominantly in pyramidal neurons, but it can also be detected in a small population of GABAergic neurons that are neither horizontal nor bitufted neurons.
Suppression of breast cancer growth and metastasis by a serpin myoepithelium-derived serine proteinase inhibitor expressed in the mammary myoepithelial cells
Authors: Xiao Guowei , Liu Yiliang E. , Gentz Reiner , Sang Qingxiang A. , Ni Jian , Goldberg Itzhak D. , Shi Y. Eric
Published: July 2002

A serpin was identified in normal mammary gland by differential cDNA sequencing.
In situ
hybridization has detected this serpin exclusively in the myoepithelial cells on the normal and noninvasive mammary epithelial side of the basement membrane and thus was named myoepithelium-derived serine proteinase inhibitor (MEPI). No MEPI expression was detected in the malignant breast carcinomas. MEPI encodes a 405-aa precursor, including an 18-residue secretion signal with a calculated molecular mass of 46 kDa. The predicted sequence of the new protein shares 33% sequence identity and 58% sequence similarity to plasminogen activator inhibitor (PAI)-1 and PAI-2. To determine whether MEPI can modulate the
in vivo
growth and progression of human breast cancers, we transfected a full-length MEPI cDNA into human breast cancer cells and studied the orthotopic growth of MEPI-transfected vs. control clones in the mammary fat pad of athymic nude mice. Overexpression of MEPI inhibited the invasion of the cells in the
in vitro
invasion assay. When injected orthotopically into nude mice, the primary tumor volumes, axillary lymph node metastasis, and lung metastasis were significantly inhibited in MEPI-transfected clones as compared with controls. The expression of MEPI in myoepithelial cells may prevent breast cancer malignant progression leading to metastasis.
Molecular basis of fast inactivation in voltage and Ca
2+
-activated K
+
channels: A transmembrane β-subunit homolog
Authors: Wallner Martin , Meera Pratap , Toro Ligia
Published: July 2002

Voltage-dependent and calcium-sensitive K
+
(MaxiK) channels are key regulators of neuronal excitability, secretion, and vascular tone because of their ability to sense transmembrane voltage and intracellular Ca
2+
. In most tissues, their stimulation results in a noninactivating hyperpolarizing K
+
current that reduces excitability. In addition to noninactivating MaxiK currents, an inactivating MaxiK channel phenotype is found in cells like chromaffin cells and hippocampal neurons. The molecular determinants underlying inactivating MaxiK channels remain unknown. Herein, we report a transmembrane β subunit (β2) that yields inactivating MaxiK currents on coexpression with the pore-forming α subunit of MaxiK channels. Intracellular application of trypsin as well as deletion of 19 N-terminal amino acids of the β2 subunit abolished inactivation of the α subunit. Conversely, fusion of these N-terminal amino acids to the noninactivating smooth muscle β1 subunit leads to an inactivating phenotype of MaxiK channels. Furthermore, addition of a synthetic N-terminal peptide of the β2 subunit causes inactivation of the MaxiK channel α subunit by occluding its K
+
-conducting pore resembling the inactivation caused by the “ball” peptide in voltage-dependent K
+
channels. Thus, the inactivating phenotype of MaxiK channels in native tissues can result from the association with different β subunits.
Evectins: Vesicular proteins that carry a pleckstrin homology domain and localize to post-Golgi membranes
Authors: Krappa Ralf , Nguyen Andrew , Burrola Patrick , Deretic Dusanka , Lemke Greg
Published: July 2002

We have identified two vesicular proteins, designated evectin (evt)-1 and -2. These proteins are ≈25 kDa in molecular mass, lack a cleaved N-terminal signal sequence, and appear to be inserted into membranes through a C-terminal hydrophobic anchor. They also carry a pleckstrin homology domain at their N termini, which potentially couples them to signal transduction pathways that result in the production of lipid second messengers. evt-1 is specific to the nervous system, where it is expressed in photoreceptors and myelinating glia, polarized cell types in which plasma membrane biosynthesis is prodigious and regulated; in contrast, evt-2 is widely expressed in both neural and nonneural tissues. In photoreceptors, evt-1 localizes to rhodopsin-bearing membranes of the post-Golgi, an important transport compartment for which specific molecular markers have heretofore been lacking. The structure and subcellular distribution of evt-1 strongly implicate this protein as a mediator of post-Golgi trafficking in cells that produce large membrane-rich organelles. Its restricted cellular distribution and genetic locus make it a candidate gene for the inherited human retinopathy autosomal dominant familial exudative vitreoretinopathy and suggest that it also may be a susceptibility gene for multiple sclerosis.
Experience-dependent plasticity in the auditory cortex and the inferior colliculus of bats: Role of the corticofugal system
Authors: Gao Enquan , Suga Nobuo
Published: July 2002

In the big brown bat,
Eptesicus fuscus
, the response properties of neurons and the cochleotopic (frequency) maps in the auditory cortex (AC) and inferior colliculus can be changed by auditory conditioning, weak focal electric stimulation of the AC, or repetitive delivery of weak, short tone bursts. The corticofugal system plays an important role in information processing and plasticity in the auditory system. Our present findings are as follows. In the AC, best frequency (BF) shifts, i.e., reorganization of a frequency map, slowly develop and reach a plateau ≈180 min after conditioning with tone bursts and electric-leg stimulation. The plateau lasts more than 26 h. In the inferior colliculus, on the other hand, BF shifts rapidly develop and become the largest at the end of a 30-min-long conditioning session. The shifted BFs return (i.e., recover) to normal in ≈180 min. The collicular BF shifts are not a consequence of the cortical BF shifts. Instead, they lead the cortical BF shifts. The collicular BF shifts evoked by conditioning are very similar to the collicular and cortical BF shifts evoked by cortical electrical stimulation. Therefore, our working hypothesis is that, during conditioning, the corticofugal system evokes subcortical BF shifts, which in turn boost cortical BF shifts. The cortical BF shifts otherwise would be very small. However, whether the cortical BF shifts are consequently boosted depends on nonauditory systems, including nonauditory sensory cortices, amygdala, basal forebrain, etc., which determine the behavioral relevance of acoustic stimuli.
Pseudorabies virus expressing enhanced green fluorescent protein: A tool for
in vitro
electrophysiological analysis of transsynaptically labeled neurons in identified central nervous system circuits
Authors: Smith Bret N. , Banfield Bruce W. , Smeraski Cynthia A. , Wilcox Christine L. , Dudek F. Edward , Enquist Lynn W. , Pickard Gary E.
Published: July 2002

Physiological properties of central nervous system neurons infected with a pseudorabies virus were examined
in vitro
by using whole-cell patch-clamp techniques. A strain of pseudorabies virus (PRV 152) isogenic with the Bartha strain of PRV was constructed to express an enhanced green fluorescent protein (EGFP) from the human cytomegalovirus immediate early promoter. Unilateral PRV 152 injections into the vitreous body of the hamster eye transsynaptically infected a restricted set of retinorecipient neurons including neurons in the hypothalamic suprachiasmatic nucleus (SCN) and the intergeniculate leaflet (IGL) of the thalamus. Retinorecipient SCN neurons were identified in tissue slices prepared for
in vitro
electrophysiological analysis by their expression of EGFP. At longer postinjection times, retinal ganglion cells in the contralateral eye also expressed EGFP, becoming infected after transsynaptic uptake and retrograde transport from infected retinorecipient neurons. Retinal ganglion cells that expressed EGFP were easily identified in retinal whole mounts viewed under epifluorescence. Whole-cell patch-clamp recordings revealed that the physiological properties of PRV 152-infected SCN neurons were within the range of properties observed in noninfected SCN neurons. Physiological properties of retinal ganglion cells also appeared normal. The results suggest that PRV 152 is a powerful tool for the transsynaptic labeling of neurons in defined central nervous system circuits that allows neurons to be identified
in vitro
by their expression of EGFP, analyzed electrophysiologically, and described in morphological detail.
Self-similar intermediate asymptotics for a degenerate parabolic filtration-absorption equation
Authors: Barenblatt G. I. , Bertsch M. , Chertock A. E. , Prostokishin V. M.
Published: July 2002

The equation ∂

t

u = u∂

xx

2

u −
(
c
− 1)(∂

x

u
)
2
is known in literature as a qualitative mathematical model of some biological phenomena. Here this equation is derived as a model of the groundwater flow in a water-absorbing fissurized porous rock; therefore, we refer to this equation as a filtration-absorption equation. A family of self-similar solutions to this equation is constructed. Numerical investigation of the evolution of non-self-similar solutions to the Cauchy problems having compactly supported initial conditions is performed. Numerical experiments indicate that the self-similar solutions obtained represent intermediate asymptotics of a wider class of solutions when the influence of details of the initial conditions disappears but the solution is still far from the ultimate state: identical zero. An open problem caused by the nonuniqueness of the solution of the Cauchy problem is discussed.
The mechanical properties of
Saccharomyces cerevisiae
Authors: Smith Alexander E. , Zhang Zhibing , Thomas Colin R. , Moxham Kennith E. , Middelberg Anton P. J.
Published: July 2002

Cell-wall mechanical properties play an integral part in the growth and form of
Saccharomyces cerevisiae
. In contrast to the tremendous knowledge on the genetics of
S. cerevisiae
, almost nothing is known about its mechanical properties. We have developed a micromanipulation technique to measure the force required to burst single cells and have recently established a mathematical model to extract the mechanical properties of the cell wall from such data. Here we determine the average surface modulus of the
S. cerevisiae
cell wall to be 11.1 ± 0.6 N/m and 12.9 ± 0.7 N/m in exponential and stationary phases, respectively, giving corresponding Young's moduli of 112 ± 6 MPa and 107 ± 6 MPa. This result demonstrates that yeast cell populations strengthen as they enter stationary phase by increasing wall thickness and hence the surface modulus, without altering the average elastic properties of the cell-wall material. We also determined the average breaking strain of the cell wall to be 82% ± 3% in exponential phase and 80% ± 3% in stationary phase. This finding provides a failure criterion that can be used to predict when applied stresses (e.g., because of fluid flow) will lead to wall rupture. This work analyzes yeast compression experiments in different growth phases by using engineering methodology.
T-cell receptor antagonists induce Vav phosphorylation by selective activation of Fyn kinase
Authors: Huang Jianyong , Tilly Darcie , Altman Amnon , Sugie Katsuji , Grey Howard M.
Published: July 2002

T cell receptor (TCR) antagonists inhibit antigen-induced T cell activation and by themselves fail to induce phenotypic changes associated with T cell activation. However, we have recently shown that TCR antagonists are inducers of antigen-presenting cell (APC)–T cell conjugates. The signaling pathway associated with this cytoskeleton-dependent event appears to involve tyrosine phosphorylation and activation of Vav. In this study, we investigated the role played by the protein tyrosine kinases Fyn, Lck, and ZAP-70 in antagonist-induced signaling pathway. Antagonist stimulation increased tyrosine phosphorylation and kinase activity of Fyn severalfold, whereas little or no increase in Lck and ZAP-70 activity was observed. Second, TCR stimulation of Lck−, FynhiJurkat cells induced strong tyrosine phosphorylation of Vav. In contrast, minimal increase in tyrosine phosphorylation of Vav was observed in Lckhi, FynloJurkat cells. Finally, study of T cells from a Fyn-deficient TCR transgenic mouse also showed that Fyn was required for tyrosine phosphorylation and activation of Vav induced by both antagonist and agonist peptides. The deficiency in Vav phosphorylation in Fyn-deficient T cells was associated with a defect in the formation of APC–T cell conjugates when T cells were stimulated with either agonist or antagonist peptide. We conclude from these results that Vav is a selective substrate for Fyn, especially under conditions of low-affinity TCR-mediated signaling, and that this signaling pathway involving Fyn, Vav, and Rac-1 is required for the cytoskeletal reorganization that leads to T cell–APC conjugates and the formation of the immunologic synapse.
Creatine kinase, an ATP-generating enzyme, is required for thrombin receptor signaling to the cytoskeleton
Authors: Mahajan Vinit B. , Pai Karnire S. , Lau Alice , Cunningham Dennis D.
Published: July 2002

Thrombin orchestrates cellular events after injury to the vascular
system and extravasation of blood into surrounding tissues. The
pathophysiological response to thrombin is mediated by
protease-activated receptor-1 (PAR-1), a seven-transmembrane G
protein-coupled receptor expressed in the nervous system that is
identical to the thrombin receptor in platelets, fibroblasts, and
endothelial cells. Once activated by thrombin, PAR-1 induces rapid and
dramatic changes in cell morphology, notably the retraction of growth
cones, axons, and dendrites in neurons and processes in astrocytes. The
signal is conveyed by a series of localized ATP-dependent reactions
directed to the actin cytoskeleton. How cells meet the dynamic and
localized energy demands during signal transmission is unknown. Using
the yeast two-hybrid system, we identified an interaction between PAR-1
cytoplasmic tail and the brain isoform of creatine kinase, a key
ATP-generating enzyme that regulates ATP within subcellular
compartments. The interaction was confirmed
in vitro
and
in vivo
. Reducing creatine kinase levels or its
ATP-generating potential inhibited PAR-1-mediated cellular shape
changes as well as a PAR-1 signaling pathway involving the activation
of RhoA, a small G protein that relays signals to the cytoskeleton.
Thrombin-stimulated intracellular calcium release was not affected. Our
results suggest that creatine kinase is bound to PAR-1 where it may be
poised to provide bursts of site-specific high-energy phosphate
necessary for efficient receptor signal transduction during
cytoskeletal reorganization.
The Relationship between Reaction Time and Psychometric Intelligence in a Rural Guatemalan Adolescent Population
Authors: Choudhury Naseem , Gorman Kathleen S.
Published: July 2002

In industrialized countries reaction time has been found to be related to measures of intelligence and cognitive abilities. Little, however, is known about the validity of using such tasks in nonindustrialized countries. The present research investigated the association between reaction time and psychometric intelligence in a rural Guatemalan adolescent population. Results indicated that speed and consistency of processing on reaction time tasks were related to psychometric intelligence. However, the magnitude of these relationships were considerably smaller than those reported in industrialized populations. Reaction time task performance accounted for less than 5% of the variance in psychometric intelligence. Findings suggest that although reaction time tasks are associated with intelligence, the predictive validity of such measures needs to be established before use in nontraditional populations.
Ethnic Identity of the Setus and the Estonian–Russian Border Dispute
Authors: Jääts Indrek
Published: July 2002

The Setus are an ethnic group, small in numbers, in the southeastern part of the Republic of Estonia and the Russian territories bordering on Estonia (Petseri raion of the Pskov oblast). The Setus can be seen as ethnographic raw material that both Estonian and Russian nationalists have attempted to claim. Generally, the Setus has been viewed as an ethnographic subgroup of Estonians and their language as part of the South Estonian dialect. Unlike the Estonians, who are predominantly Lutheran by tradition, the Setus are Orthodox. The specific characteristics of the Setus have emerged as a result of the combined influence of religious and linguistic peculiarities and a historic fate that is different from the Estonian. Because of the fact that they were considered Estonians when the censuses took place, the exact number of the Setus is unknown; however, I estimate the number of the Setus living in Setumaa and in Estonian towns to be about 5,000–6,000.
Further Education Participation, European Expansion and European Erasure
Authors: Brine Jacky
Published: July 2002

Abstract From within the context of the planned expansion of the European Union (EU) to include the 12 applicant states from central and eastern Europe and the predicted reduction of the European financial support given to the UK, the article draws on empirical data to explore the impact of the European Social Fund (ESF) on the further education sector and the process of widening participation. Despite the significance of the ESF in implementing vocational education and training (VET) policy, it has been consistently erased by both the Conservative and Labour administrations. Whereas this erasure can be traced back to Britain's membership in 1973, the focus of the article is on the period 1997‐2000, for Labour's Welfare to Work policies draw heavily on the financial support given by the EU through the ESF. It is suggested that, whereas the continued erasure of the Fund can be contextualised by the continued (and politically contentious) membership of the EU, its public erasure enables it to play a vital, flexible and unaccountable role in the VET policies of Conservative and Labour administrations.
Mother-infant interaction and acculturation: II. Behavioural coherence and correspondence in Japanese American and South American families
Authors: Cote Linda R. , Bornstein Marc H.
Published: July 2002

This study examined cultural generality and specificity in relations among and between mothers’ and infants’ behaviours in 37 Japanese American and 40 South American acculturating families. Few relations among mothers’ behaviours emerged, except for that between mothers’ social behaviour and other types of maternal behaviour, which appear to reflect the common collectivist orientation of these two cultural groups. Few relations among infants’ behaviours emerged, suggesting that there is independence and plasticity in infant behavioural organisation. Several expected relations between mothers’ and infants’ behaviours emerged, pointing to some universal characteristics in mother-infant interactions.
Adolescents’ Implicit Theories of Physical Phenomena: A Matter of Gravity
Authors: Pulos Steven
Published: July 2002

Individual differences in conceptions of physical phenomena are frequently seen in normal adolescents. The individual differences may be based on isolated conceptual entities or deeper implicit theories. This study investigated whether there is an implicit theory of gravity underlying adolescents’ performance on a local gravity task, Piaget’s Water Level Task, and their understanding of planetary gravity. These two tasks and three measures of intellectual ability were administered to 80 adolescents between the 6th and 9th grade. The two gravity concepts were highly correlated ( r = .51, P .001) and the correlation could not be explained by a common relation with intellectual abilities. Furthermore, the pattern of correlation with abilities did not differ significantly for the two tasks. The results are consistent with a notion of a general implicit theory of gravity that may underlie quite divergent tasks.
Gender Stereotyping in Portuguese Children Living in Portugal and Abroad: Effects of Migration, Age, and Gender
Authors: Neto Félix
Published: July 2002

Williams and Best’s (1990) study of the development of sex stereotype knowledge among young children in 24 countries was extended to Portuguese subjects living in Portugal and abroad. Subjects were 720 children (aged 8-11 years), with each age group evenly divided by gender, and each age/gender group evenly divided into three places of residence: urban and rural areas in Portugal, and in France. Subjects were administered the Sex Stereotype Measure II (SSM II) in which children select between male and female silhouettes as the person described in brief stories containing highly sex-typed psychological characteristics (aggressive, emotional, etc.). The results of the study indicated an increase in sex stereotype knowledge from 8 to 11 years, a greater knowledge of the migrants’ children in France than of the children living in urban and rural areas in Portugal, and a greater knowledge of female stereotype traits than male stereotype traits.
Children’s Representations of Parental Loss due to War
Authors: Rafman Sandra , Canfield Joyce , Barbas José , Kaczorowski Janusz
Published: July 2002

To study the specific contribution of parental loss in war, play representations and family interviews of thirty 4- to 6-year-old immigrant children (15 war-orphaned) from war-torn Central American countries were analysed. The play of children who had lost a parent through death or “disappearance in war differed significantly from that of children who had not. Two years after the loss, war-orphaned children symbolically re-enacted the manner of the parental death or disappearance in play but could not sustain the play scenario for long. Expressions of imminent danger and emptiness were prevalent but anger and vengeance were not. Children who had been exposed to war without parental loss depicted situations and themes reflecting issues associated with their age. Low levels of secrecy surrounding reasons for immigration or past losses, parental acceptance of death, remarriage and presence of extended family characterised the content of family interviews in both groups.
Role of macrophage migration inhibitory factor (MIF) in allergic and endotoxin‐induced airway inflammation in mice
Authors: Korsgren M. , Källström L. , Uller L. , Bjerke T. , Sundler F. , Persson C. G. A. , Korsgren O.
Published: July 2002

Macrophage migration inhibitory factor (MIF) has recently been forwarded as a critical regulator of inflammatory conditions, and it has been hypothesized that MIF may have a role in the pathogenesis of asthma and chronic obstructive pulmonary disease (COPD). Hence, we examined effects of MIF immunoneutralization on the development of allergen‐induced eosinophilic inflammation as well as on lipopolysaccaride (LPS)‐induced neutrophilic inflammation in lungs of mice. Anti‐MIF serum validated with respect to MIF neutralizing capacity or normal rabbit serum (NRS) was administered i.p. repeatedly during allergen aerosol exposure of ovalbumin (OVA)‐immunized mice in an established model of allergic asthma, or once before instillation of a minimal dose of LPS into the airways of mice, a tentative model of COPD. Anti‐MIF treatment did not affect the induced lung tissue eosinophilia or the cellular composition of bronchoalveolar lavage fluid (BALF) in the asthma model. Likewise, anti‐MIF treatment did not affect the LPS‐induced neutrophilia in lung tissue, BALF, or blood, nor did it reduce BALF levels of tumor necrosis factor‐α (TNF‐α) and macrophage inflammatory protein–1 α (MIP–1 α). The present data suggest that MIF is not critically important for allergen‐induced eosinophilic, and LPS‐induced neutrophilic responses in lungs of mice. These findings do not support a role of MIF inhibition in the treatment of inflammatory respiratory diseases.
Inflammatory cytokines in newborn infants
Authors: Sarandakou A. , Giannaki G. , Malamitsi-Puchner A. , Rizos D. , Hourdaki E. , Protonotariou E. , Phocas I.
Published: July 2002

Serum levels of IL‐1β, IL‐6 and TNF‐α were measured in 48 healthy, termed neonates on the 1st (N1), 5th (N5) and 40th (N40) day after birth, compared with those in maternal serum (MS), umbilical cord (UC) and adult controls. Cytokine values in N1 and N5 were significantly elevated, than those in UC and in controls (p < 0.0001). IL‐1β and IL‐6 declined significantly from N1 to N40 (p < 0.0001), while TNF‐α increased significantly from N1 to N5 and declined thereafter. MS ∞ IL‐1β and IL‐6, but not MS ∞ TNF‐α, were significantly higher than those of controls (p < 0.0001). IL‐1β values depended on the mode of delivery. In conclusion, the increased concentrations of IL‐1 β, IL‐6 and TNF‐α during the perinatal period might suggest their involvement in an inflammation like process during normal parturition, and reflect also a newborn immune response to the stress of delivery and environmental changes.
A Short Alcohol Withdrawal Scale (SAWS): development and psychometric properties
Authors: Gossop Michael , Keaney Francis , Stewart Duncan , Marshall E. Jane , Strang John
Published: July 2002

Abstract The measurement of alcohol withdrawal symptoms is important for the assessment of the alcohol withdrawal syndrome and for the evaluation of the effectiveness of withdrawal treatment interventions. There continues to be a need for an instrument for the measurement of alcohol withdrawal severity which is short, easy to understand (especially by respondents who may feel anxious, confused or physically ill) and easy to administer (for example, within clinical services with limited time and resources).This paper describes the development and psychometric properties of the 10‐item Short AlcoholWithdrawal Scale. The SAWS includes five items which represent psychological symptoms (anxious, confused, restless, miserable, memory problems) which accounted for 47% of the variance. A further five items represent physical symptoms (tremor, nausea, heart pounding, sleep disturbance, sweating) and accounted for 11% of the variance. The procedures leading to the development of the scale are described and results are presented showing that the SAWS has high internal consistency, and good construct and concurrent validity.
Expression and Characterization of Human Ecto‐ATPase and Chimeras with CD39 Ecto‐Apyrase
Authors: Hicks‐Berger Carrie A. , Kirley Terence L.
Published: July 2002

Human ecto‐ATPase (ecto‐nucleoside triphosphate d iphosphohydrolase 2 [eNTPDase2], also known as CD39L1) has been expressed and characterized in COS cells. It exhibits some unusual enzymology that is similar to a few members of this class of proteins but different from the majority of the family members. Hydrolysis of ATP by human ecto‐ATPase is nonlinear with time, and its activity is stimulated/stabilized by both the lectin concanavalin A and the chemical cross‐linking agent disuccinimidyl suberate. Like other members of the eNTPDase family, the human ecto‐ATPase is a tetramer, the activity of which depends on its glycosylation. Chimeras of this protein with human CD39 (eNTPDase1) were constructed to test the hypothesis that the N‐terminal half of these proteins regulates nucleotide specificity. The two chimeras generated demonstrated that the N‐terminal half of these proteins is crucial for determining the relative activities of the nucleoside diand triphosphatases. Chemical cross‐linking of the two chimeras suggests that disuccinimidyl suberate interacts with the C‐terminal half of ecto‐ATPase in a manner that results in an increase of activity for both the ecto‐ATPase and the ecto‐apyrase/ecto‐ATPase chimera.
Tenascin Supports Lymphocyte Rolling
Authors: Clark Rachael A. , Erickson Harold P. , Springer Timothy A.
Published: July 2002

Tenascin is a large extracellular matrix molecule expressed at specific sites in the adult, including immune system tissues such as the bone marrow, thymus, spleen, and T cell areas of lymph nodes. Tenascin has been reported to have both adhesive and anti-adhesive effects in static assays. We report here that tenascin supports the tethering and rolling of lymphocytes and lymphoblastic cell lines under flow conditions. Binding was calcium dependent and was not inhibited by treatment of lymphocytes with O-glycoprotease or a panel of glycosidases including neuraminidase and heparitinase but was inhibited by treatment of cells with proteinase K. Binding was to the fibrinogen-like terminal domain of tenascin as determined by antibody blocking studies and binding to recombinant tenascin proteins. When compared to rolling of the same cell type on E-selectin, rolling on tenascin was found to be smoother at all shear stresses tested, suggesting that cells formed a larger number of bonds on the tenascin substrate than on the E-selectin substrate. When protein plating densities were adjusted to give similar profiles of cell detachment under increasing shears, the density of tenascin was 8.5-fold greater than that of E-selectin. Binding to tenascin was not dependent on any molecules previously identified as tenascin receptors and is likely to involve a novel tenascin receptor on lymphocytes. We postulate that the ability of tenascin to support lymphocyte rolling may reflect its ability to support cell migration and that this interaction may be used by lymphocytes migrating through secondary lymphoid organs.