Shedding of the soluble IL-6 receptor is triggered by Ca2+ mobilization, while basal release is predominantly the product of differential mRNA splicing in THP-1 cells

The soluble IL-6 receptor (sIL-6R) is generated through either proteolytic shedding of the cognate receptor (PC-sIL-6R), or released as the product of differential mRNA splicing (DS-sIL-6R). Using monocytic THP-1 cells, we demonstrate that both mechanisms are independently regulated, and that each process contributes to sIL-6R production. Shedding of the IL-6R was activated by the Ca2+ ionophore, ionomycin, and inhibited by the TNF-alpha protease inhibitor (TAPI). In contrast, basal sIL-6R release was unaffected by Ca2+ depletion and largely insensitive to TAPI. Moreover, although IL-6R shedding was inactivated by serum starvation, non-stimulated production remained intact. Basal sIL-6R production via differential mRNA splicing was shown through the inhibitory action of brefeldin A and an enzyme-linked immunosorbent assay specific for DS-sIL-6R. Release of this isoform was unaffected by ionomycin or TAPI, indicating that Ca2+ mobilization activates PC-sIL-6R generation, but not DS-sIL-6R. The divergent control of these sIL-6R isoforms indicates that they may independently influence the inflammatory response.     

Impact on human health of Salmonella spp. on pork in The Netherlands and the anticipated effects of some currently proposed control strategies

Cell-cell and cell-extracellular matrix interactions are fundamental processes involved in cell migration and tissue remodeling. Both the cyclic regeneration of the human endometrium during the menstrual cycle as well as the process of embryo implantation involve such dynamic interactions. It has become quite clear that integrin adhesion molecules expressed on the surface of cells play critical roles in the transmission of signals from the extracellular milieu to the cells. It is these signals that presumably regulate the behavior of these cells during major morphogenetic processes. In recent years, work in human endometrium and trophoblasts has uncovered both the regulated and constitutive expression of integrin subunits and their extracellular matrix ligands in these tissues. In addition, attempts have been made to correlate pathological states related to either infertility or abnormal pregnancy to the aberrant expression of several of these integrins. The purpose of the present review is to describe briefly our present state of knowledge of the expression of integrins in human endometrium and trophoblasts and provide the reader with the necessary background needed to understand, at the cellular and molecular levels, processes in reproduction such as embryo implantation.     

Community-acquired pneumonia

This seminar reviews the aetiology, clinical presentation, approach to diagnosis, and management of immunocompetent adults with community-acquired pneumonia (CAP). Pneumonia is a common clinical entity, particularly among the elderly. A thorough understanding of the epidemiology and microbiology of CAP is essential for appropriate diagnosis and management. Although the microbiology of CAP has remained relatively stable over the last decade, there is new information on the incidence of atypical pathogens, particularly in patients not admitted to hospital, and new information on the incidence of pathogens in cases of severe CAP and in CAP in the elderly. Recent studies have provided new data on risk factors for mortality in CAP, which can assist the clinician in decisions about the need for hospital admission. The emergence of antimicrobial resistance in Streptococcus pneumoniae, the organism responsible for most cases of CAP, has greatly affected the approach to therapy, especially in those patients who are treated empirically. Guidelines for the therapy of CAP have been published by the American Thoracic Society, the British Thoracic Society, and, most recently, the Infectious Diseases Society of America. These guidelines differ in their emphasis on empirical versus pathogenic-specific management.     

B lymphocytes are critical antigen-presenting cells for the initiation of T cell-mediated autoimmune diabetes in nonobese diabetic mice

Nonobese diabetic (NOD) mice genetically deficient in B lymphocytes (NODJg mu(null)) are resistant to T cell-mediated autoimmune insulin-dependent diabetes mellitus (IDDM). Ig infusions from diabetic NOD donors did not abrogate IDDM resistance in NODJg mu(null) mice. However, T cell responses to the candidate pancreatic beta cell autoantigen glutamic acid decarboxylase (GAD), but not the control Ag keyhole limpet hemocyanin, were eliminated in NODJg mu(null) mice. To initially test whether they contribute to IDDM as APC, NOD B lymphocytes were transferred into NODJg mu(null) recipients. B lymphocytes transferred into unmanipulated NODJg mu(null) recipients were rejected by MHC class I-restricted T cells. Stable T and B lymphocyte repopulation was achieved in irradiated NODJg mu(null) mice reconstituted with syngeneic bone marrow admixed with NOD B lymphocytes. IDDM susceptibility was restored in NODJg mu(null) mice reconstituted with syngeneic marrow plus B lymphocytes, but not with syngeneic marrow only. T cell responses to GAD were restored only in NODJg mu(null) mice reconstituted with syngeneic marrow plus B lymphocytes. Hence, B lymphocytes appear to contribute to IDDM in NOD mice as APC with a preferential ability to present certain beta cell Ags such as GAD to autoreactive T cells.     

Routine intraoperative laparoscopic cholangiography

BACKGROUND: Whether intraoperative laparoscopic cholangiography should be routine is debatable. METHODS: We reviewed the cholangiography experience in 669 consecutive laparoscopic cholecystectomies. RESULTS: Mean age of the patients was 39 years, 78% were female, and 29% had acute cholecystitis. Cholecystectomy was completed laparoscopically in 606 (91%). Laparoscopic cholangiography was completed in 562 (93%) and 348 (62%) were routine (no preoperative indication). The mean operating time in 1996 was 61 minutes. Out of the 348 routine cholangiograms, 17 demonstrated evidence of unsuspected choledocholithiasis. Five patients had choledocholithiasis documented by laparoscopic common bile duct exploration and/or endoscopic retrograde cholangiopancreatography. Two patients had normal postoperative cholangiopancreatography. One of 10 patients managed expectantly was readmitted postoperatively with obstructive jaundice. In 4 patients, routine cholangiography revealed unexpected anatomy, and in 2, this prevented misidentification and transection of the common bile duct. CONCLUSION: Laparoscopic cholangiography is safe, quick, detects unsuspected choledocholithiasis, and can prevent common bile duct transection. It should be routine.     

Automatic alerting does not speed late motoric processes in a reaction-time task

When an irrelevant 'accessory' stimulus is presented at about the same time as the imperative signal in a choice reaction time-task, the latency of the voluntary response is markedly reduced. The most prominent cognitive theories agree that this effect is attributable to a brief surge in arousal ('automatic alerting'), but they disagree over whether the facilitation is localized to a late, low-level motoric process or to an earlier stage, the process of orienting to and then perceptually categorizing the reaction stimulus. To test these alternative hypotheses, we used the onset of the lateralized readiness potential (a movement-related brain potential) as a temporal landmark to partition mean reaction time into two time segments. The first segment included the time required to perceive the visual stimulus and decide which hand to react with; the second included only motoric processes. Presentation of an irrelevant acoustic stimulus shortened the first interval but had no effect on the second. We therefore rejected the motoric hypothesis.     

Phytochromes and cryptochromes in the entrainment of the Arabidopsis circadian clock

Circadian clocks are synchronized by environmental cues such as light. Photoreceptor-deficient Arabidopsis thaliana mutants were used to measure the effect of light fluence rate on circadian period in plants. Phytochrome B is the primary high-intensity red light photoreceptor for circadian control, and phytochrome A acts under low-intensity red light. Cryptochrome 1 and phytochrome A both act to transmit low-fluence blue light to the clock. Cryptochrome 1 mediates high-intensity blue light signals for period length control. The presence of cryptochromes in both plants and animals suggests that circadian input pathways have been conserved throughout evolution.     

Tissue phenotype depends on reciprocal interactions between the extracellular matrix and the structural organization of the nucleus

What determines the nuclear organization within a cell and whether this organization itself can impose cellular function within a tissue remains unknown. To explore the relationship between nuclear organization and tissue architecture and function, we used a model of human mammary epithelial cell acinar morphogenesis. When cultured within a reconstituted basement membrane (rBM), HMT-3522 cells form polarized and growth-arrested tissue-like acini with a central lumen and deposit an endogenous BM. We show that rBM-induced morphogenesis is accompanied by relocalization of the nuclear matrix proteins NuMA, splicing factor SRm160, and cell cycle regulator Rb. These proteins had distinct distribution patterns specific for proliferation, growth arrest, and acini formation, whereas the distribution of the nuclear lamina protein, lamin B, remained unchanged. NuMA relocalized to foci, which coalesced into larger assemblies as morphogenesis progressed. Perturbation of histone acetylation in the acini by trichostatin A treatment altered chromatin structure, disrupted NuMA foci, and induced cell proliferation. Moreover, treatment of transiently permeabilized acini with a NuMA antibody led to the disruption of NuMA foci, alteration of histone acetylation, activation of metalloproteases, and breakdown of the endogenous BM. These results experimentally demonstrate a dynamic interaction between the extracellular matrix, nuclear organization, and tissue phenotype. They further show that rather than passively reflecting changes in gene expression, nuclear organization itself can modulate the cellular and tissue phenotype.     

Nucleolar localization elements in U8 snoRNA differ from sequences required for rRNA processing

U8 small nucleolar RNA (snoRNA) is essential for metazoan ribosomal RNA (rRNA) processing in nucleoli. The sequences and structural features in Xenopus U8 snoRNA that are required for its nucleolar localization were analyzed. Fluorescein-labeled U8 snoRNA was injected into Xenopus oocyte nuclei, and fluorescence microscopy of nucleolar preparations revealed that wild-type Xenopus U8 snoRNA localized to nucleoli, regardless of the presence or nature of the 5' cap on the injected U8 snoRNA. Nucleolar localization was observed when loops or stems in the 5' portion of U8 that are critical for U8 snoRNA function in rRNA processing were mutated. Therefore, sites of interaction in U8 snoRNA that potentially tether it to pre-rRNA are not essential for nucleolar localization of U8. Boxes C and D are known to be nucleolar localization elements (NoLEs) for U8 snoRNA and other snoRNAs of the Box C/D family. However, the spatial relationship of Box C to Box D was not crucial for U8 nucleolar localization, as demonstrated here by deletion of sequences in the two stems that separate them. These U8 mutants can localize to nucleoli and function in rRNA processing as well. The single-stranded Cup region in U8, adjacent to evolutionarily conserved Box C, functions as a NoLE in addition to Boxes C and D. Cup is unique to U8 snoRNA and may help bind putative protein(s) needed for nucleolar localization. Alternatively, Cup may help to retain U8 snoRNA within the nucleolus.