bluuebunny/crossref_metadata_2025 huggingface dataset:
The basic helix–loop–helix transcription factor capsulin controls spleen organogenesis
Authors: Lu JianRong , Chang Priscilla , Richardson James A. , Gan Lin , Weiler Hartmut , Olson Eric N.
Published: July 2002

Formation of numerous internal organs involves reciprocal epithelial–mesenchymal signaling and subsequent patterning and growth of the organ primordium. Capsulin is a basic helix–loop–helix transcription factor expressed in mesenchymal cells that encapsulate the epithelial primordia of internal organs, including the kidney and lung, as well as the epicardium, which gives rise to the coronary arteries. Capsulin is also expressed in the mesothelium that gives rise to the spleen. We demonstrate that mice homozygous for a
capsulin
null mutation fail to form a spleen. The homeobox genes
Hox11
and
Bapx1
, shown previously to be essential regulators of spleen organogenesis, and a
lacZ
reporter introduced into the
capsulin
locus, were expressed in the early splenic primordium, derived from the splanchnic mesoderm, of homozygous mutant embryos. However, this primordium failed to develop beyond an initial group of precursor cells and underwent rapid apoptosis. The phenotype of
capsulin
mutant mice demonstrates that capsulin acts within a subpopulation of splanchnic mesodermal cells to control an essential early step in spleen organogenesis that is likely to represent a point of regulatory convergence of the
capsulin
,
Hox11
, and
Bapx1
genes.
The Concept of Wisdom: A Cross‐cultural Comparison
Authors: Takahashi Masami , Bordia Prashant
Published: July 2002

To examine the meaning of wisdom cross‐culturally, American, Australian, Indian, and Japanese samples judged the similarity of seven personality descriptors: “aged,” “awakened,” “discreet,” “experienced,” “intuitive,” “knowledgeable,” and “wise.” Multidimensional scaling (MDS) analysis revealed different clustering patterns for the Western (American and Australian) and the Eastern (Indian and Japanese) samples. For the Westerners, “wise” was clustered with “experienced” and “knowledgeable,” whereas the Easterners associated “wise” with “discreet.” Further, the Western samples selected “wise” and “knowledgeable” as the favourable descriptors for an ideal self whereas mixed results were obtained from the Eastern samples. The results suggest that the conceptualization of wisdom in the West differs from that in the East, with the former emphasizing the cognitive dimension and the latter stressing the cognitive and the affective dimensions.
Effect of ricinoleic acid in acute and subchronic experimental models of inflammation
Authors: Vieira Celme , Evangelista Stefano , Cirillo Rocco , Lippi Annalisa , Maggi Carlo Alberto , Manzini Stefano
Published: July 2002

Observational studies indicate that topical application of ricinoleic acid (RA), the main component of castor oil, exerts remarkable analgesic and anti‐inflammatory effects. Pharmacological characterization has shown similarities between the effects of RA and those of capsaicin, suggesting a potential interaction of this drug on sensory neuropeptide‐mediated neurogenic inflammation. The aim of this study was to assess RA anti‐inflammatory activities in comparison with capsaicin in several models of acute and subchronic inflammation. The acute inflammation was induced by intradermal injection of carrageenan in the mouse or by histamine in the guinea‐pig eyelid. In either experiment, the extent of the oedema thickness was measured. Subchronic oedema was induced by complete Freund′s adjuvant injection in the ventral right paw of mice. Tissue substance P (SP) was measured in the carrageenan experiments by radioimmunoassay (RIA). It was found that the acute topical application of RA (0.9 mg/mouse) or capsaicin (0.09 mg/mouse) significantly increased the mouse paw oedema induced by carrageenan, while an 8‐day repeated topical treatment with the same doses of both compounds resulted in a marked inhibition of carrageenaninduced paw oedema matched by a reduction in SP tissue levels. Similar effects were found against histamine‐induced eyelid oedema in guinea‐pigs after acute or repeated application of RA or capsaicin. RA and capsaicin given for 1–3 weeks reduced the established oedema induced by Freund′s adjuvant, a subchronic model of inflammation, particularly if given by the intradermal route. Either in mouse paw or in guineapig eyelid, capsaicin but not RA by itself produced a slight hyperemia and activation of a behavioural response (e.g. scratching of the eyelids). On the basis of the present results, RA may be seen as a new capsaicin‐like, non‐pungent anti‐inflammatory agent suitable for peripheral application.
On the Genesis of the Canonical Labor Supply Model
Authors: Derobert Laurent
Published: July 2002

The individual's labor supply model, usually called leisure-income, is very well known in labor economics. It determines the time a person spends on the labor market by studying it as the outcome of a trade-off between leisure and income. The model is developed in almost every book on microeconomics. But strangely enough, although all economists know the model, no one seems to know precisely its origins.
A Two‐Rate Hypothesis for Patterns of Retention in Psychosocial Treatments of Cocaine Dependence: Findings from a Study of African‐American Men and a Review of the Published Data
Authors: Pena José M. , Franklin Robert R. , Rice Janet C. , Foulks Edward F. , Bland Irma J. , Shervington Denese , James Arnold
Published: July 2002

In this article, we examine patterns of retention in psychosocial treatment programs for cocaine dependence. We present new data from a comparison trial of Drug Counseling and Supportive‐Expressive Psychotherapy and review published data from all studies utilizing psychosocial interventions alone. We compared Drug Counseling and Psychotherapy on rates of pretreatment and during‐treatment attrition in a sample of 294 African‐American men seeking treatment for cocaine dependence (mean age, 37.6). Survival analyses were utilized to identify significant differences in during‐treatment attrition between the two treatments and to identify significant changes in the rate of attrition during the course of each treatment. We then compared the patterns of retention in this study with those from other available published reports of psychosocial treatments for cocaine abuse. The weekly during‐treatment attrition rate was not constant in either treatment condition, and the change in rate of attrition occurred at week six for both Drug Counseling and Psychotherapy. Comparison with other studies suggested that the during‐treatment pattern of attrition among most psychosocial treatments for cocaine abuse is typified by two rates, with the rate of subject attrition early in treatment being greater than the rate of later attrition and also exhibiting greater variance. Future studies of treatment retention should identify significant shifts in the rate of during‐treatment attrition, examine if the pattern of attrition is typified by two rates, and, if so, determine where the shift occurs. Future studies should also assess if changes in the rate of during‐treatment attrition signal the timeframes within which strategies that enhance retention can be implemented in the treatment program.
Safety Assessment Studies in Nonhuman Primates
Authors: Hobson William
Published: July 2002

Worldwide regulatory guidelines for drug safety evaluations recommend testing in both a rodent and a nonrodent species. Non-human primates, which are phylogenetically close to man, are often thought of as the “ideal” nonrodent species. Historically, because of conservation issues, biosafety concerns, and price and supply issues, use of nonhuman primates in toxicology programs has been restricted to special cases. Recently, however, biopharmaceutical scientists have turned to primates as the only nonhuman species in which the biological activities of some drugs are expressed. Also, as the cost of test article for toxicology studies has increased, there has been a corresponding increase in the use of primates because of their smaller body size compared to dogs. With increasing demand, primatologists have solved the price, supply, and conservation issues by worldwide development of breeding centers that produce adequate numbers of well-characterized rhesus and cynomolgus macaques. New international personnel protective standards, shipping and quarantine requirements have addressed some of the public health concerns. However, tuberculosis, Herpesvirus simiae (B virus) and the “Ebola-like” hemorrhagic primate viruses remain of concern to primate researchers. With new requirements for specialized training, housing, equipment, and procedures for primate research and husbandry, many pharmaceutical companies now outsource their primate toxicology work to contract research organizations. The effort to “harmonize” international regulatory requirements for nonclinical toxicology has led to more uniformity in nonhuman primate study design. Typical study designs and procedures are discussed.
Streptozotocin and Insulin-Dependent Diabetes Induce Changes in Hepatic Cytoarchitecture in Mice
Authors: Watkins John B. , Gardner Phillip A. , Feczko John D. , Klueber Kathleen M.
Published: July 2002

Streptozotocin (STZ) causes both direct organ toxicity and diabetes, and both actions can affect the structure and function of many organs. Because biliary excretory function changes with time after STZ injection, it was hypothesized that morphological changes would occur in livers from mice made diabetic with STZ. Blood glucose concentrations were elevated above that in control mice from day 3 onward. Liver tissue collected on days 1, 3, 5, 7, 14, 21, 28, 35, and 42 following a single administration of STZ (200 mg/kg IV) was prepared for electron microscopy using standard procedures. Liver samples from vehicle control mice were obtained on each experimental day for comparison. Morphological changes on days 1 and 3 included a swelling of the hepatic sinusoids, an apparent widening between hepatocyte borders, and deterioration of the microvilli of the bile canaliculi. On days 5, 7, 14, 21, and 28, the liver exhibited normal extracellular space and canaliculi with regenerated microvilli. However, findings similar to those from days 1 and 3 were observed in the liver samples from days 35 and 42. The most dramatic effect seen on day 42 was the dilation of extracellular space. Hepatic sinusoids were enlarged and canalicular microvilli appeared to have degenerated. Findings from days 1 and 3 may be attributed to STZ hepatotoxicity with subsequent normalization of the fiver, whereas the alterations observed on days 35 and 42 are probably a manifestation of diabetes mellitus, because these changes became more extensive with progression of the disease.
12-Month Chronic Toxicity Study of LY275585 (Human Insulin Analog) Administered Subcutaneously to Fischer 344 Rats
Authors: Zimmermann J. L. , Truex L. L.
Published: July 2002

The monocomponent insulin analog LY275585 was administered to Fischer 344 rats in daily subcutaneous doses of 0, 20, or 200 U/kg for 12 months. Each treatment group consisted of 30 males and 30 females, and the vehicle control group consisted of 35 of each sex. Changes related to the pharmacologic activity of LY275585 included an increase in body weight, body weight gain, food consumption, and efficacy of food utilization in male and female rats given 200 U/kg. Pharmacologically related clinical chemistry effects occurring at 200 U/kg were an increase in mean serum glucose (24 h postdose) of males and females, a slight decrease in mean serum triglyceride of females, and decreased mean serum cholesterol of males and females. Fewer effects occurred in low-dose rats (20 U/kg) and included an increase of efficiency of food utilization only in female rats, a slight decrease in mean serum triglyceride in females, and decreased mean serum cholesterol in low-dose males and females. Three male and two female rats administered 200 U/kg died during the treatment period. Death of one male was attributed to hypoglycemia. Cause of death of four other high-dose rats was either not apparent, or the result of a variety of intercurrent disease processes unrelated to treatment. Survival in the low-dose (20 U/kg) and control groups was similar; one rat in each group died prior to treatment termination. The only compound-related lesion associated with treatment was a non-dose-related enhancement of the degree and incidence of inflammation at the site of subcutaneous injection. There were no compound-related changes in background lesions including neoplasms, or in hematologic or urinalysis values. In a comparison study, pharmacokinetic profiles of LY275585 and serum glucose values were determined in groups of 30 male and female rats administered single doses of 20 or 200 U/kg. Plasma levels of LY275585 peaked after 30 min, were dose related, and were similar in male and female rats. The hypoglycemia produced in rats receiving a single dose of 20 U/kg was maximal, suggesting saturation of the insulin receptor sites at this dose. The dose of 200 U/kg of LY275585 was, therefore, a supramaximal pharmacological dose when compared to an average daily human dose of 0.5 U/kg/ d. It is concluded that no toxicologically significant changes, other than moderate injection site inflammation, occurred in Fischer 344 rats treated with LY275585 at doses of 20 and 200 U/kg for 12 months.
Differences in propensity for drinking alcohol are reflected in subunit‐ and region‐specific GABAA receptor levels
Authors: TYNDALE RACHEL F. , TOMKINS DENISE M.
Published: July 2002

Enhancement of GABAA receptor activity within certain discrete brain areas can elicit increased ethanol consumption, supporting a regionally specific role for GABAergic mechanisms in modulating ethanol reinforcement. The present study investigated if rats, which were in the highest (HES) or lowest (LES) 15th percentile of ethanol self‐administration, had different GABAA receptor levels. MaleWistar rats (n=30) were trained to self‐administer ethanol for 8 weeks followed by assessment of GABAA receptor mRNAs. In the last operant session the HES rats (4/group) were consuming significantly more ethanol than the LES rats (1.31±‐0.31 g/kg versus 0.02±0.02 g/kg; p<0.001). Significant GABAA receptor mRNA differences were found between the groups, which were subunit‐ and brain region‐specific, with higher mRNA levels in the HES rats in the dorsal raphe (α2, α3, γ1), medial raphe (α3, α5, β1, β3, γ1), cerebellum (α1, α6, β3, γ2long) and hippocampus (β1, β3, γ1 and γ2long). The elevated cerebellum α1 mRNA level in the HES rats was confirmed using Western blotting (mean density units ±SEM; LES rats 0.460 ±0.005 versus HES rats 0.610 ± 0.006, p=0.03). These data suggest that the differences in GABA receptors were due either to the different propensities of the groups to consume ethanol or were caused by their differing ethanol exposure.
Language Development Following Brain Injury In Early Childhood: A Longitudinal Case Study
Authors: Trudeau Natacha , Poulin‐Dubois Diane , Joanette Yves
Published: July 2002

The present longitudinal case study was designed to investigate the possibility that a traumatic brain injury (TBI) occurring during the second year of life, while significant lexical and grammatical competencies are emerging, could have an impact on subsequent language development. Thus, the language development of a very young girl (BL) who suffered a TBI at the age of 17 months was monitored for 6 months following the injury. Different procedures were used to measure her lexical and grammatical development: monthly parental checklists, free‐play sessions and word‐learning tasks. BLA's results were compared with two control groups (n = 5 and 9) matched for age and gender. Overall, the results are consistent with the classical view of acquired language disorders in children: despite an initial decrease in the use of her premorbid vocabulary, BL showed no durable significant impairment on any measure of lexical or grammatical development.
Targeted Disruption of the Pemphigus Vulgaris Antigen (Desmoglein 3) Gene in Mice Causes Loss of Keratinocyte Cell Adhesion with a Phenotype Similar to Pemphigus Vulgaris
Authors: Koch Peter J. , Mahoney M G. , Ishikawa Hiroyasu , Pulkkinen Leena , Uitto Jouni , Shultz Leonard , Murphy George F. , Whitaker-Menezes Diana , Stanley John R.
Published: July 2002

In patients with pemphigus vulgaris (PV), autoantibodies against desmoglein 3 (Dsg3) cause loss of cell–cell adhesion of keratinocytes in the basal and immediate suprabasal layers of stratified squamous epithelia. The pathology, at least partially, may depend on protease release from keratinocytes, but might also result from antibodies interfering with an adhesion function of Dsg3. However, a direct role of desmogleins in cell adhesion has not been shown. To test whether Dsg3 mediates adhesion, we genetically engineered mice with a targeted disruption of the DSG3 gene. DSG3 −/− mice had no DSG3 mRNA by RNase protection assay and no Dsg3 protein by immunofluorescence (IF) and immunoblots. These mice were normal at birth, but by 8–10 d weighed less than DSG3 +/− or +/+ littermates, and at around day 18 were grossly runted. We speculated that oral lesions (typical in PV patients) might be inhibiting food intake, causing this runting. Indeed, oropharyngeal biopsies showed erosions with histology typical of PV, including suprabasilar acantholysis and “tombstoning” of basal cells. EM showed separation of desmosomes. Traumatized skin also had crusting and suprabasilar acantholysis. Runted mice showed hair loss at weaning. The runting and hair loss phenotype of DSG3 −/− mice is identical to that of a previously reported mouse mutant, balding (bal). Breeding indicated that bal is coallelic with the targeted mutation. We also showed that bal mice lack Dsg3 by IF, have typical PV oral lesions, and have a DSG3 gene mutation. These results demonstrate the critical importance of Dsg3 for adhesion in deep stratified squamous epithelia and suggest that pemphigus autoantibodies might interfere directly with such a function.
Integrin and Cadherin Synergy Regulates Contact Inhibition of Migration and Motile Activity
Authors: Huttenlocher Anna , Lakonishok Margot , Kinder Melissa , Wu Stanley , Truong Tho , Knudsen Karen A. , Horwitz Alan F.
Published: July 2002

Integrin receptors play a central role in cell migration through their roles as adhesive receptors for both other cells and extracellular matrix components. In this study, we demonstrate that integrin and cadherin receptors coordinately regulate contact-mediated inhibition of cell migration. In addition to promoting proliferation (Sastry, S., M. Lakonishok, D. Thomas, J. Muschler, and A. Horwitz. 1996. J. Cell Biol. 133:169–184), ectopic expression of the α5 integrin in cultures of primary quail myoblasts promotes a striking contact-mediated inhibition of cell migration. Myoblasts ectopically expressing α5 integrin (α5 myoblasts) move normally when not in contact, but upon contact, they show inhibition of migration and motile activity (i.e., extension and retraction of membrane protrusions). As a consequence, these cells tend to grow in aggregates and do not migrate to close a wound. This phenotype is also seen with ectopic expression of β1 integrin, paxillin, or activated FAK (CD2 FAK) and therefore appears to result from enhanced integrin-mediated signaling. The contact inhibition observed in the α5 myoblasts is mediated by N-cadherin, whose expression is upregulated more than fivefold. Perturbation studies using low calcium conditions, antibody inhibition, and ectopic expression of wild-type and mutant N-cadherins all implicate N-cadherin in the contact inhibition of migration. Ectopic expression of N-cadherin also produces cells that show inhibited migration upon contact; however, they do not show suppressed motile activity, suggesting that integrins and cadherins coordinately regulate motile activity. These observations have potential importance to normal and pathologic processes during embryonic development and tumor metastasis.
Endothelial Cell E- and P-Selectin and Vascular Cell Adhesion Molecule-1 Function as Signaling Receptors
Authors: Lorenzon P. , Vecile E. , Nardon E. , Ferrero E. , Harlan J.M. , Tedesco F. , Dobrina A.
Published: July 2002

Previous studies have shown that polymorphonuclear leukocyte (PMN) adherence to endothelial cells (EC) induces transient increases in EC cytosolic free calcium concentration ([Ca2+]i) that are required for PMN transit across the EC barrier (Huang, A.J., J.E. Manning, T.M. Bandak, M.C. Ratau, K.R. Hanser, and S.C. Silverstein. 1993. J. Cell Biol. 120:1371–1380). To determine whether stimulation of [Ca2+]i changes in EC by leukocytes was induced by the same molecules that mediate leukocyte adherence to EC, [Ca2+]i was measured in Fura2-loaded human EC monolayers. Expression of adhesion molecules by EC was induced by a pretreatment of the cells with histamine or with Escherichia coli lipopolysaccharide (LPS), and [Ca2+]i was measured in single EC after the addition of mAbs directed against the EC adhesion proteins P-selectin, E-selectin, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), or platelet/endothelial cell adhesion molecule-1 (PECAM-1). Both anti–P- and anti–E-selectin mAb, as well as anti–VCAM-1 mAb, induced transient increases in EC [Ca2+]i that were comparable to those induced by 200 μM histamine. In contrast, no effect was obtained by mAbs directed against the endothelial ICAM-1 or PECAM-1. PMN adherence directly stimulated increases in [Ca2+]i in histamine- or LPS-treated EC. mAbs directed against leukocyte CD18 or PECAM-1, the leukocyte counter-receptors for endothelial ICAM-1 and PECAM-1, respectively, did not inhibit PMN-induced EC activation. In contrast, mAb directed against sialyl Lewis x (sLex), a PMN ligand for endothelial P- and E-selectin, completely inhibited EC stimulation by adherent PMN. Changes in EC [Ca2+]i were also observed after adherence of peripheral blood monocytes to EC treated with LPS for 5 or 24 h. In these experiments, the combined addition of mAbs to sLex and VLA-4, the leukocyte counter-receptor for endothelial VCAM-1, inhibited [Ca2+]i changes in the 5 h–treated EC, whereas the anti–VLA-4 mAb alone was sufficient to inhibit [Ca2+]i changes in the 24 h-treated EC. Again, no inhibitory effect was observed with an anti-CD18 or anti–PECAM-1 mAb. Of note, the conditions that induced changes in EC [Ca2+]i, i.e., mAbs directed against endothelial selectins or VCAM-1, and PMN or monocyte adhesion to EC via selectins or VCAM-1, but not via ICAM-1 or PECAM-1, also induced a rearrangement of EC cytoskeletal microfilaments from a circumferential ring to stress fibers. We conclude that, in addition to their role as adhesion receptors, endothelial selectins and VCAM-1 mediate endothelial stimulation by adhering leukocytes.
Role of CDMP-1 in Skeletal Morphogenesis: Promotion of Mesenchymal Cell Recruitment and Chondrocyte Differentiation
Authors: Tsumaki Noriyuki , Tanaka Kazuhiro , Arikawa-Hirasawa Eri , Nakase Takanobu , Kimura Tomoatsu , Thomas J. Terrig , Ochi Takahiro , Luyten Frank P. , Yamada Yoshihiko
Published: July 2002

Cartilage provides the template for endochondral ossification and is crucial for determining the length and width of the skeleton. Transgenic mice with targeted expression of recombinant cartilage-derived morphogenetic protein-1 (CDMP-1), a member of the bone morphogenetic protein family, were created to investigate the role of CDMP-1 in skeletal formation. The mice exhibited chondrodysplasia with expanded cartilage, which consists of the enlarged hypertrophic zone and the reduced proliferating chondrocyte zone. Histologically, CDMP-1 increased the number of chondroprogenitor cells and accelerated chondrocyte differentiation to hypertrophy. Expression of CDMP-1 in the notochord inhibited vertebral body formation by blocking migration of sclerotome cells to the notochord. These results indicate that CDMP-1 antagonizes the ventralization signals from the notochord. Our study suggests a molecular mechanism by which CDMP-1 regulates the formation, growth, and differentiation of the skeletal elements.
Monocyte Adhesion and Spreading on Human Endothelial Cells Is Dependent on Rho-regulated Receptor Clustering
Authors: Wójciak-Stothard Beata , Williams Lynn , Ridley Anne J.
Published: July 2002

The GTPase Rho is known to mediate the assembly of integrin-containing focal adhesions and actin stress fibers. Here, we investigate the role of Rho in regulating the distribution of the monocyte-binding receptors E-selectin, ICAM-1, and VCAM-1 in human endothelial cells. Inhibition of Rho activity with C3 transferase or N19RhoA, a dominant negative RhoA mutant, reduced the adhesion of monocytes to activated endothelial cells and inhibited their spreading. Similar effects were observed after pretreatment of endothelial cells with cytochalasin D. In contrast, dominant negative Rac and Cdc42 proteins did not affect monocyte adhesion or spreading. C3 transferase and cytochalasin D did not alter the expression levels of monocyte-binding receptors on endothelial cells, but did inhibit clustering of E-selectin, ICAM-1, and VCAM-1 on the cell surface induced by monocyte adhesion or cross-linking antibodies. Similarly, N19RhoA inhibited receptor clustering. Monocyte adhesion and receptor cross-linking induced stress fiber assembly, and inhibitors of myosin light chain kinase prevented this response but did not affect receptor clustering. Finally, receptor clusters colocalized with ezrin/moesin/ radixin proteins. These results suggest that Rho is required in endothelial cells for the assembly of stable adhesions with monocytes via the clustering of monocyte-binding receptors and their association with the actin cytoskeleton, independent of stress fiber formation.
Nischarin, a Novel Protein That Interacts with the Integrin α5 Subunit and Inhibits Cell Migration
Authors: Alahari Suresh K. , Lee Jung Weon , Juliano Rudy L.
Published: July 2002

Integrins have been implicated in key cellular functions, including cytoskeletal organization, motility, growth, survival, and control of gene expression. The plethora of integrin α and β subunits suggests that individual integrins have unique biological roles, implying specific molecular connections between integrins and intracellular signaling or regulatory pathways. Here, we have used a yeast two-hybrid screen to identify a novel protein, termed Nischarin, that binds preferentially to the cytoplasmic domain of the integrin α5 subunit, inhibits cell motility, and alters actin filament organization. Nischarin is primarily a cytosolic protein, but clearly associates with α5β1, as demonstrated by coimmunoprecipitation. Overexpression of Nischarin markedly reduces α5β1-dependent cell migration in several cell types. Rat embryo fibroblasts transfected with Nischarin constructs have “basket-like” networks of peripheral actin filaments, rather than typical stress fibers. These observations suggest that Nischarin might affect signaling to the cytoskeleton regulated by Rho-family GTPases. In support of this, Nischarin expression reverses the effect of Rac on lamellipodia formation and selectively inhibits Rac-mediated activation of the c-fos promoter. Thus, Nischarin may play a negative role in cell migration by antagonizing the actions of Rac on cytoskeletal organization and cell movement.
Cyclin-dependent kinases govern formation and maintenance of the nucleolus
Authors: Sirri Valentina , Hernandez-Verdun Danièle , Roussel Pascal
Published: July 2002

In higher eukaryotic cells, the nucleolus is a nuclear compartment assembled at the beginning of interphase, maintained during interphase, and disorganized during mitosis. Even if its structural organization appears to be undissociable from its function in ribosome biogenesis, the mechanisms that govern the formation and maintenance of the nucleolus are not elucidated. To determine if cell cycle regulators are implicated, we investigated the putative role of the cyclin-dependent kinases (CDKs) on ribosome biogenesis and nucleolar organization. Inhibition of CDK1–cyclin B during mitosis leads to resumption of rDNA transcription, but is not sufficient to induce proper processing of the pre-rRNA and total relocalization of the processing machinery into rDNA transcription sites. Similarly, at the exit from mitosis, both translocation of the late processing machinery and pre-rRNA processing are impaired in a reversible manner by CDK inhibitors. Therefore, CDK activity seems indispensable for the building of functional nucleoli. Furthermore, inhibition of CDKs in interphasic cells also hampered proper pre-rRNA processing and induced a dramatic disorganization of the nucleolus. Thus, we propose that the mechanisms governing both formation and maintenance of functional nucleoli involve CDK activities and couple the cell cycle to ribosome biogenesis.
On the Key Role of Secondary Lymphoid Organs in Antiviral Immune Responses Studied in Alymphoplastic (aly/aly) and Spleenless (Hox11−/−) Mutant Mice
Authors: Karrer Urs , Althage Alana , Odermatt Bernhard , Roberts Charles W.M. , Korsmeyer Stanley J. , Miyawaki Shigeki , Hengartner Hans , Zinkernagel Rolf M.
Published: July 2002

The role of the spleen and of other organized secondary lymphoid organs for the induction of protective antiviral immune responses was evaluated in orphan homeobox gene 11 knockout mice (Hox11−/−) lacking the spleen, and in homozygous alymphoplastic mutant mice (aly/aly) possessing a structurally altered spleen but lacking lymph nodes and Peyer's patches. Absence of the spleen had no major effects on the immune response, other than delaying the antibody response by 1–2 d. In aly/aly mice, the thymus-independent IgM response against vesicular stomatitis virus (VSV) was delayed and reduced, whereas the T-dependent switch to the protective IgG was absent. Therefore, aly/aly mice were highly susceptible to VSV infection. Since aly/aly spleen cells yielded neutralizing IgM and IgG after adoptive transfer into recipients with normally structured secondary lymphoid organs, these data suggest that the structural defect was mainly responsible for inefficient T–B cooperation. Although aly/aly mice generated detectable, but reduced, CTL responses after infection with vaccinia virus (VV) and lymphocytic choriomeningitis virus (LCMV), the elimination of these viruses was either delayed (VV) or virtually impossible (LCMV); irrespective of the dose or the route of infection, aly/aly mice developed life-long LCMV persistence. These results document the critical role of organized secondary lymphoid organs in the induction of naive T and B cells. These structures also provide the basis for cooperative interactions between antigen-presenting cells, T cells, and B cells, which are a prerequisite for recovery from primary virus infections via skin or via blood.
IgE Enhances Mouse Mast Cell FcεRI Expression In Vitro and In Vivo: Evidence for a Novel Amplification Mechanism in IgE-dependent Reactions
Authors: Yamaguchi Masao , Lantz Chris S. , Oettgen Hans C. , Katona Ildy M. , Fleming Tony , Miyajima Ichiro , Kinet Jean-Pierre , Galli Stephen J.
Published: July 2002

The binding of immunoglobulin E (IgE) to high affinity IgE receptors (FcεRI) expressed on the surface of mast cells primes these cells to secrete, upon subsequent exposure to specific antigen, a panel of proinflammatory mediators, which includes cytokines that can also have immunoregulatory activities. This IgE- and antigen-specific mast cell activation and mediator production is thought to be critical to the pathogenesis of allergic disorders, such as anaphylaxis and asthma, and also contributes to host defense against parasites. We now report that exposure to IgE results in a striking (up to 32-fold) upregulation of surface expression of FcεRI on mouse mast cells in vitro or in vivo. Moreover, baseline levels of FcεRI expression on peritoneal mast cells from genetically IgE-deficient (IgE −/−) mice are dramatically reduced (by ∼83%) compared with those on cells from the corresponding normal mice. In vitro studies indicate that the IgE-dependent upregulation of mouse mast cell FcεRI expression has two components: an early cycloheximide-insensitive phase, followed by a later and more sustained component that is highly sensitive to inhibition by cycloheximide. In turn, IgE-dependent upregulation of FcεRI expression significantly enhances the ability of mouse mast cells to release serotonin, interleukin-6 (IL-6), and IL-4 in response to challenge with IgE and specific antigen. The demonstration that IgE-dependent enhancement of mast cell FcεRI expression permits mast cells to respond to antigen challenge with increased production of proinflammatory and immunoregulatory mediators provides new insights into both the pathogenesis of allergic diseases and the regulation of protective host responses to parasites.
Invariant Chain–independent Function of H-2M in the Formation of Endogenous Peptide–Major Histocompatibility Complex Class II Complexes In Vivo
Authors: Kovats Susan , Grubin Catherine E. , Eastman Susan , deRoos Paul , Dongre Ashok , Kaer Luc Van , Rudensky Alexander Y.
Published: July 2002

Efficient loading of major histocompatibility complex class II molecules with peptides requires the invariant chain (Ii) and the class II–like molecule H-2M. Recent in vitro biochemical studies suggest that H2-M may function as a chaperone to rescue empty class II dimers. To test this hypothesis in vivo, we generated mice lacking both Ii and H-2M (Ii−/−M−/−). Antigen presenting cells (APCs) from Ii−/−M−/− mice, as compared with APCs from Ii−/− mice, exhibit a significant reduction in their ability to present self-peptides to a panel of class II I-Ab–restricted T cells. As a consequence of this defect in the loading of self peptides, CD4+ thymocyte development is profoundly impaired in Ii−/−M−/− mice, resulting in a peripheral CD4+ T cell population with low levels of T cell receptor expression. These findings are consistent with the idea that H-2M functions as a chaperone in the peptide loading of class II molecules in vivo.
Initiation of Autoimmune Diabetes by Developmentally Regulated Presentation of Islet Cell Antigens in the Pancreatic Lymph Nodes
Authors: Höglund Petter , Mintern Justine , Waltzinger Caroline , Heath William , Benoist Christophe , Mathis Diane
Published: July 2002

Little is known about the events triggering lymphocyte invasion of the pancreatic islets in prelude to autoimmune diabetes. For example, where islet-reactive T cells first encounter antigen has not been identified. We addressed this issue using BDC2.5 T cell receptor transgenic mice, which express a receptor recognizing a natural islet beta cell antigen. In BDC2.5 animals, activated T cells were found only in the islets and the lymph nodes draining them, and there was a close temporal correlation between lymph node T cell activation and islet infiltration. When naive BDC2.5 T cells were transferred into nontransgenic recipients, proliferating cells were observed only in pancreatic lymph nodes, and this occurred significantly before insulitis was detectable. Surprisingly, proliferation was not seen in 10-day-old recipients. This age-dependent dichotomy was reproduced in a second transfer system based on an unrelated antigen artificially expressed on beta cells. We conclude that beta cell antigens are transported specifically to pancreatic lymph nodes, where they trigger reactive T cells to invade the islets. Systemic or extrapancreatic T cell priming, indicative of activation via molecular mimicry or superantigens, was not seen. Compromised presentation of beta cell antigens in the pancreatic lymph nodes of juvenile animals may be the root of a first “checkpoint” in diabetes progression.
Cross-Presentation of Glycoprotein 96–Associated Antigens on Major Histocompatibility Complex Class I Molecules Requires Receptor-Mediated Endocytosis
Authors: Singh-Jasuja Harpreet , Toes René E.M. , Spee Pieter , Münz Christian , Hilf Norbert , Schoenberger Stephen P. , Ricciardi-Castagnoli Paola , Neefjes Jacques , Rammensee Hans-Georg , Arnold-Schild Danièle , Schild Hansjörg
Published: July 2002

Heat shock proteins (HSPs) like glycoprotein (gp)96 (glucose-regulated protein 94 [grp94]) are able to induce specific cytotoxic T lymphocyte (CTL) responses against cells from which they originate. Here, we demonstrate that for CTL activation by gp96-chaperoned peptides, specific receptor-mediated uptake of gp96 by antigen-presenting cells (APCs) is required. Moreover, we show that in both humans and mice, only professional APCs like dendritic cells (DCs), macrophages, and B cells, but not T cells, are able to bind gp96. The binding is saturable and can be inhibited using unlabeled gp96 molecules. Receptor binding by APCs leads to a rapid internalization of gp96, which colocalizes with endocytosed major histocompatibility complex (MHC) class I and class II molecules in endosomal compartments. Incubation of gp96 molecules isolated from cells expressing an adenovirus type 5 E1B epitope with the DC line D1 results in the activation of E1B-specific CTLs. This CTL activation can be specifically inhibited by the addition of irrelevant gp96 molecules not associated with E1B peptides. Our results demonstrate that only receptor-mediated endocytosis of gp96 molecules leads to MHC class I–restricted re-presentation of gp96-associated peptides and CTL activation; non–receptor-mediated, nonspecific endocytosis is not able to do so. Thus, we provide evidence on the mechanisms by which gp96 is participating in the cross-presentation of antigens from cellular origin.
Delayed Expulsion of the Nematode Trichinella spiralisIn Mice Lacking the Mucosal Mast Cell–Specific Granule Chymase, Mouse Mast Cell Protease-1
Authors: Knight Pamela A. , Wright Steven H. , Lawrence Catherine E. , Paterson Yvonne Y.W. , Miller Hugh R.P.
Published: July 2002

Expulsion of gastrointestinal nematodes is associated with pronounced mucosal mast cell (MMC) hyperplasia, differentiation, and activation, accompanied by the systemic release of MMC granule chymases (chymotrypsin-like serine proteases). The β-chymase mouse mast cell protease-1 (mMCP-1) is expressed predominantly by intraepithelial MMCs, and levels in the bloodstream and intestinal lumen are maximal at the time of worm expulsion in parasitized mice. To address the in vivo functions of MMC-specific β-chymases, we have generated transgenic mice that lack the mMCP-1 gene. They were backcrossed onto a congenic BALB/c background to investigate the response to nematode infection. The deletion of the mMCP-1 gene is associated with significantly delayed expulsion of Trichinella spiralis and increased deposition of muscle larvae in BALB/c mice despite the presence of normal and sometimes increased numbers of MMCs. Neither worm fecundity nor worm burdens were altered in Nippostrongylus-infected mMCP-1−/− BALB/c mice. These data demonstrate, for the first time, that the ablation of an MMC-derived effector molecule compromises the expulsion process.
Combined Stimulation with the T Helper Cell Type 2 Cytokines Interleukin (Il)-4 and IL-10 Induces Mouse Mast Cell Apoptosis
Authors: Yeatman C. Fitzhugh , Jacobs-Helber Sarah M. , Mirmonsef Paria , Gillespie Sheila R. , Bouton Lawrence Andrew , Collins Henrietta A. , Sawyer Stephen T. , Shelburne Christopher P. , Ryan John J.
Published: July 2002

Mast cells are found in connective and mucosal tissues throughout the body. Their activation via immunoglobulin E (IgE)–antigen interactions is promoted by T helper cell type 2 (Th2) cytokines and leads to the sequelae of allergic disease. We now report a mechanism by which Th2 cytokines can regulate mast cell survival. Specifically, we find that interleukin (IL)-4 and IL-10 induce apoptosis in IL-3–dependent bone marrow–derived mast cells and peritoneal mast cells. This process required 6 d of costimulation with IL-3, IL-4, and IL-10, and expression of signal transducer and activator of transcription 6 (Stat6). Apoptosis was coupled with decreased expression of bcl-xL and bcl-2. While this process occurred independent of the Fas pathway, culture in IL-3+IL-4+IL-10 greatly sensitized mast cells to Fas-mediated death. Additionally, we found that IgE cross-linkage or stimulation with stem cell factor enhanced the apoptotic abilities of IL-4 and IL-10. Finally, IL-3–independent mastocytomas and mast cell lines were resistant to apoptosis induced by IL-3+IL-4+IL-10. These data offer evidence of Th2 cytokine–mediated homeostasis whereby these cytokines both elicit and limit allergic responses. Dysregulation of this pathway may play a role in allergic disease and mast cell tumor survival.
Complement Activation Selectively Potentiates the Pathogenicity of the IgG2b and IgG3 Isotypes of a High Affinity Anti-Erythrocyte Autoantibody
Authors: da Silveira Samareh Azeredo , Kikuchi Shuichi , Fossati-Jimack Liliane , Moll Thomas , Saito Takashi , Verbeek J. Sjef , Botto Marina , Walport Mark J. , Carroll Michael , Izui Shozo
Published: July 2002

By generating four IgG isotype-switch variants of the high affinity 34–3C anti-erythrocyte autoantibody, and comparing them to the IgG variants of the low affinity 4C8 anti-erythrocyte autoantibody that we have previously studied, we evaluated in this study how high affinity binding to erythrocytes influences the pathogenicity of each IgG isotype in relation to the respective contributions of Fcγ receptor (FcγR) and complement. The 34–3C autoantibody opsonizing extensively circulating erythrocytes efficiently activated complement in vivo (IgG2a = IgG2b > IgG3), except for the IgG1 isotype, while the 4C8 IgG autoantibody failed to activate complement. The pathogenicity of the 34–3C autoantibody of IgG2b and IgG3 isotypes was dramatically higher (>200-fold) than that of the corresponding isotypes of the 4C8 antibody. This enhanced activity was highly (IgG2b) or totally (IgG3) dependent on complement. In contrast, erythrocyte-binding affinities only played a minor role in in vivo hemolytic activities of the IgG1 and IgG2a isotypes of 34–3C and 4C8 antibodies, where complement was not or only partially involved, respectively. The remarkably different capacities of four different IgG isotypes of low and high affinity anti-erythrocyte autoantibodies to activate FcγR-bearing effector cells and complement in vivo demonstrate the role of autoantibody affinity maturation and of IgG isotype switching in autoantibody-mediated pathology.
Rational 𝑆¹-equivariant homotopy theory
Authors: Scull Laura
Published: July 2002

We give an algebraicization of rational

S
1

S^1

-equivariant homotopy theory. There is an algebraic category of “

T

\mathbb {T}

-systems” which is equivalent to the homotopy category of rational

S
1

S^1

-simply connected

S
1

S^1

-spaces. There is also a theory of “minimal models” for

T

\mathbb {T}

-systems, analogous to Sullivan’s minimal algebras. Each

S
1

S^1

-space has an associated minimal

T

\mathbb {T}

-system which encodes all of its rational homotopy information, including its rational equivariant cohomology and Postnikov decomposition.
Largest known twin primes
Authors: Indlekofer Karl-Heinz , Járai Antal
Published: July 2002

The numbers

697053813
⋅

2

16352

±
1

697053813\cdot 2^{16352}\pm 1

are twin primes.
Aurifeuillian factorizations and the period of the Bell numbers modulo a prime
Authors: Wagstaff Samuel
Published: July 2002

We show that the minimum period modulo

p
p

of the Bell exponential integers is

(

p
p

−
1
)

/

(
p
−
1
)

(p^p-1)/(p-1)

for all primes

p
>
102

p>102

and several larger

p
p

. Our proof of this result requires the prime factorization of these periods. For some primes

p
p

the factoring is aided by an algebraic formula called an Aurifeuillian factorization. We explain how the coefficients of the factors in these formulas may be computed.
On quadrature convergence of extended Lagrange interpolation
Authors: Gautschi Walter , Li Shikang
Published: July 2002

Quadrature convergence of the extended Lagrange interpolant

L

2
n
+
1

f

L_{2n+1}f

for any continuous function

f
f

is studied, where the interpolation nodes are the

n
n

zeros

τ
i

\tau _i

of an orthogonal polynomial of degree

n
n

and the

n
+
1

n+1

zeros

τ
^

j

\hat {\tau }_j

of the corresponding “induced” orthogonal polynomial of degree

n
+
1

n+1

. It is found that, unlike convergence in the mean, quadrature convergence does hold for all four Chebyshev weight functions. This is shown by establishing the positivity of the underlying quadrature rule, whose weights are obtained explicitly. Necessary and sufficient conditions for positivity are also obtained in cases where the nodes

τ
i

\tau _i

and

τ
^

j

\hat {\tau }_j

interlace, and the conditions are checked numerically for the Jacobi weight function with parameters

α
\alpha

and

β
\beta

. It is conjectured, in this case, that quadrature convergence holds for

|

α

|

≤

1
2

,
 

|

β

|

≤

1
2

| \alpha | \leq \frac {1}{2}, ~ | \beta | \leq \frac {1}{2}

.
Turán’s pure power sum problem
Authors: Cheer A. , Goldston D.
Published: July 2002

Let

1
=

z

1

≥

|

z

2

|

≥
⋯
≥

|

z

n

|

1 = z_{1} \ge |z_{2}|\ge \cdots \ge |z_{n}|

be

n
n

complex numbers, and consider the power sums

s

ν

=

z

1

ν

+

z

2

ν

+
⋯
+

z

n

ν

s_{\nu }= {z_{1}}^{\nu }+ {z_{2}}^{\nu }+ \cdots + {z_{n}}^{\nu }

,

1
≤
ν
≤
n

1\le \nu \le n

. Put

R

n

=
min

max

1
≤
ν
≤
n

|

s

ν

|

R_{n} = \min \max _{1\le \nu \le n} |s_{\nu }|

, where the minimum is over all possible complex numbers satisfying the above. Turán conjectured that

R

n

>
A

R_{n} > A

, for

A
A

some positive absolute constant. Atkinson proved this conjecture by showing

R

n

>
1

/

6

R_{n} > 1/6

. It is now known that

1

/

2
>

R

n

>
1

1/2>R_{n} > 1

, for

n
≥
2

n\ge 2

. Determining whether

R

n

→
1

R_{n} \to 1

or approaches some other limiting value as

n
→
∞

n\to \infty

is still an open problem. Our calculations show that an upper bound for

R

n

R_{n}

decreases for

n
≤
55

n\le 55

, suggesting that

R

n

R_{n}

decreases to a limiting value less than

0.7
0.7

as

n
→
∞

n\to \infty

.
Integration of polyharmonic functions
Authors: Dimitrov Dimitar
Published: July 2002

The results in this paper are motivated by two analogies. First,

m
m

-harmonic functions in

R

n

\mathbf {R}^{n}

are extensions of the univariate algebraic polynomials of odd degree

2
m
−
1

2m-1

. Second, Gauss’ and Pizzetti’s mean value formulae are natural multivariate analogues of the rectangular and Taylor’s quadrature formulae, respectively. This point of view suggests that some theorems concerning quadrature rules could be generalized to results about integration of polyharmonic functions. This is done for the Tchakaloff-Obrechkoff quadrature formula and for the Gaussian quadrature with two nodes.