Multipotential nestin-positive stem cells isolated from adult pancreatic islets differentiate ex vivo into pancreatic endocrine, exocrine, and hepatic phenotypes

The endocrine cells of the rat pancreatic islets of Langerhans, including insulin-producing beta-cells, turn over every 40-50 days by processes of apoptosis and the proliferation and differentiation of new islet cells (neogenesis) from progenitor epithelial cells located in the pancreatic ducts. However, the administration to rats of islet trophic factors such as glucose or glucagon-like peptide 1 for 48 h results in a doubling of islet cell mass, suggesting that islet progenitor cells may reside within the islets themselves. Here we show that rat and human pancreatic islets contain a heretofore unrecognized distinct population of cells that express the neural stem cell-specific marker nestin. Nestin-positive cells within pancreatic islets express neither the hormones insulin, glucagon, somatostatin, or pancreatic polypeptide nor the markers of vascular endothelium or neurons, such as collagen IV and galanin. Focal regions of nestin-positive cells are also identified in large, small, and centrolobular ducts of the rat pancreas. Nestin-positive cells in the islets and in pancreatic ducts are distinct from ductal epithelium because they do not express the ductal marker cytokeratin 19 (CK19). After their isolation, these nestin-positive cells have an unusually extended proliferative capacity when cultured in vitro (approximately 8 months), can be cloned repeatedly, and appear to be multipotential. Upon confluence, they are able to differentiate into cells that express liver and exocrine pancreas markers, such as alpha-fetoprotein and pancreatic amylase, and display a ductal/endocrine phenotype with expression of CK19, neural-specific cell adhesion molecule, insulin, glucagon, and the pancreas/duodenum specific homeodomain transcription factor, IDX-1. We propose that these nestin-positive islet-derived progenitor (NIP) cells are a distinct population of cells that reside within pancreatic islets and may participate in the neogenesis of islet endocrine cells. The NIP cells that also reside in the pancreatic ducts may be contributors to the established location of islet progenitor cells. The identification of NIP cells within the pancreatic islets themselves suggest possibilities for treatment of diabetes, whereby NIP cells isolated from pancreas biopsies could be expanded ex vivo and transplanted into the donor/recipient.

Calcitonin precursors are reliable markers of sepsis in a medical intensive care unit

OBJECTIVE

The diagnosis of infection in critically ill patients is challenging because traditional markers of infection are often misleading. For example, serum concentrations of calcitonin precursors are increased in patients with infections. However, their predictive accuracy for the diagnosis of sepsis in unselected patients in a medical intensive care unit (ICU) is unknown. Therefore, we compared the usefulness of serum concentrations of calcitonin precursors, C-reactive protein, interleukin-6, and lactate for the diagnosis of sepsis in consecutive patients suffering from a broad range of diseases with an anticipated stay of > or =24 hrs in a medical ICU.

DESIGN

Prospective cohort study.

SETTING

Medical intensive care unit in a university medical center.

PATIENTS

101 consecutive critically ill patients.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

Blood samples were collected at various time points during the course of the disease. Systemic inflammatory response syndrome, sepsis, severe sepsis, and septic shock were diagnosed according to standardized criteria, and patients were reclassified daily without prior knowledge of the serum concentrations of calcitonin precursors or interleukin-6. At admission, 99% of the patients had systemic inflammatory response syndrome, 53% had sepsis, and 5% developed sepsis during their stay in the ICU. Calcitonin precursors, C-reactive protein, interleukin-6, and lactate levels increased with the severity of infection (p < .01, one-way analysis of variance). In a receiver operating characteristic curve analysis, calcitonin precursors were found to be the most reliable laboratory variable for the diagnosis of sepsis as compared with C-reactive protein, interleukin-6, and lactate (p < .01, for each comparison). Calcitonin precursor concentrations of >1 ng/mL had sensitivity of 89% and specificity of 94% for the diagnosis of sepsis. High serum concentrations of calcitonin precursors were associated with poor prognosis (p = .01).

CONCLUSIONS

In a medical ICU, serum calcitonin precursor concentrations are more sensitive and are specific markers of sepsis as compared with serum C-reactive protein, interleukin-6, and lactate levels.

Proteasome subunit Rpn1 binds ubiquitin-like protein domains

The yeast protein Rad23 belongs to a diverse family of proteins that contain an amino-terminal ubiquitin-like (UBL) domain. This domain mediates the binding of Rad23 to proteasomes, which in turn promotes DNA repair and modulates protein degradation, possibly by delivering ubiquitinylated cargo to proteasomes. Here we show that Rad23 binds proteasomes by directly interacting with the base subcomplex of the regulatory particle of the proteasome. A component of the base, Rpn1, specifically recognizes the UBL domain of Rad23 through its leucine-rich-repeat-like (LRR-like) domain. A second UBL protein, Dsk2, competes with Rad23 for proteasome binding, which suggests that the LRR-like domain of Rpn1 may participate in the recognition of several ligands of the proteasome. We propose that the LRR domain of Rpn1 may be positioned in the base to allow the cargo proteins carried by Rad23 to be presented to the proteasomal ATPases for unfolding. We also report that, contrary to expectation, the base subunit Rpn10 does not mediate the binding of UBL proteins to the proteasome in yeast, although it can apparently contribute to the binding of ubiquitin chains by intact proteasomes.

Characterization of the cell-wall polysaccharides of Arabidopsis thaliana leaves

The cell-wall polysaccharides of Arabidopsis thaliana leaves have been isolated, purified, and characterized. The primary cell walls of all higher plants that have been studied contain cellulose, the three pectic polysaccharides homogalacturonan, rhamnogalacturonan I and rhamnogalacturonan II, the two hemicelluloses xyloglucan and glucuronoarabinoxylan, and structural glycoproteins. The cell walls of Arabidopsis leaves contain each of these components and no others that we could detect, and these cell walls are remarkable in that they are particularly rich in phosphate buffer-soluble polysaccharides (34% of the wall). The pectic polysaccharides of the purified cell walls consist of rhamnogalacturonan I (11%), rhamnogalacturonon II (8%), and homogalacturonan (23%). Xyloglucan (XG) accounts for 20% of the wall, and the oligosaccharide fragments generated from XG by endoglucanase consist of the typical subunits of other higher plant XGs. Glucuronoarabinoxylan (4%), cellulose (14%) and protein (14%) account for the remainder of the wall. Except for the phosphate buffer-soluble pectic polysaccharides, the polysaccharides of Arabidopsis leaf cell walls occur in proportions similar to those of other plants. The structure of the Arabidopsis cell-wall polysaccharides are typical of those of many other plants.

Rad23 and Rpn10 serve as alternative ubiquitin receptors for the proteasome

The selective recognition of ubiquitin conjugates by proteasomes is a key step in protein degradation. The receptors that mediate this step have yet to be clearly defined although specific candidates exist. Here we show that the proteasome directly recognizes ubiquitin chains through a specific subunit, Rpn10, and also recognizes chains indirectly through Rad23, a reversibly bound proteasome cofactor. Both binding events can be observed in purified biochemical systems. A block substitution in the chain-binding ubiquitin interacting motif of RPN10 when combined with a null mutation in RAD23 results in a synthetic defect in protein degradation consistent with the view that the direct and indirect recognition modes function to some extent redundantly in vivo. Rad23 and the deubiquitinating enzyme Ubp6 both bind proteasome subunit Rpn1 through N-terminal ubiquitin-like domains. Surprisingly, Rad23 and Ubp6 do not compete with each other for proteasome binding. Thus, Rpn1 may act as a scaffold to assemble on the proteasome multiple proteins that act to either bind or hydrolyze multiubiquitin chains.

ATP-dependent branch migration of Holliday junctions promoted by the RuvA and RuvB proteins of E. coli

The RuvA and RuvB proteins of E. coli, which are induced as part of the cellular response to DNA damage, act together to promote the branch migration of Holliday junctions. Addition of purified RuvA and RuvB to a RecA-mediated recombination reaction stimulates the rate of strand exchange and the formation of hetero-duplex DNA. Stimulation does not occur via interaction with RecA; instead, RuvA and RuvB act directly upon recombination intermediates (Holliday junctions) made by RecA. We show that RuvAB-mediated branch migration requires ATP and can bypass UV-induced DNA lesions. At high RuvB concentrations, the requirement for RuvA is overcome, indicating that the RuvB ATPase provides the motor force for branch migration. RuvA protein provides specificity by binding to the Holliday junction, thereby reducing the requirement for RuvB by 50-fold. The newly discovered biochemical properties of RuvA, RuvB, and RuvC are incorporated into a model for the postreplicational repair of DNA following UV irradiation.

Intravenous immunoglobulin versus oral corticosteroids in acute immune thrombocytopenic purpura in childhood

In a randomised, multicentre study intravenous IgG was compared with oral corticosteroids in 108 children with untreated acute immune thrombocytopenic purpura. IgG was an efficient treatment with no severe untoward reactions. The effects of corticosteroids and IgG were identical for rapid responders, who accounted for 62% of all patients. In contrast, patients requiring more than initial treatment responded better if randomised to IgG. The serum IgG level increased two-fold after IgG. A significant rise in IgM levels was observed after both IgG and corticosteroids. The platelet-associated IgG index was high in 75% of all patients. No significant differences between the two treatment groups were found, but rapid responders had a smaller mean initial platelet-associated IgG index which returned more rapidly and more permanently to normal than that of slow responders.

Biochemical characterization of a putative axonal guidance molecule of the chick visual system

Temporal retinal axons growing in vitro on carpets of tectal membranes are deflected by cell membranes of posterior tectum. The activity responsible for this deflection can be abolished by antibodies raised against tectal membranes and the corresponding Fab fragments. Analysis of tectal membranes by two-dimensional gel electrophoresis and immunoblotting reveals a 33 kd glycoprotein that has a higher concentration in posterior than in anterior tectum. Its expression is developmentally regulated, and it is sensitive to phosphatidylinositol-specific phospholipase C. These are properties expected for a molecule responsible for the phenomena observed in experiments on in vitro guidance of retinal axons.

TSH-controlled L-thyroxine therapy reduces cholesterol levels and clinical symptoms in subclinical hypothyroidism: a double blind, placebo-controlled trial (Basel Thyroid Study)

This study evaluated the effect of physiological, TSH-guided, L-thyroxine treatment on serum lipids and clinical symptoms in patients with subclinical hypothyroidism. Sixty-six women with proven subclinical hypothyroidism (TSH, 11.7 +/- 0.8 mIU/liter) were randomly assigned to receive L-thyroxine or placebo for 48 wk. Individual L-thyroxine replacement (mean dose, 85.5 +/- 4.3 microg/d) was performed based on blinded TSH monitoring, resulting in euthyroid TSH levels (3.1 +/- 0.3 mIU/liter). Lipid concentrations and clinical scores were measured before and after treatment. Sixty-three of 66 patients completed the study. In the L-thyroxine group (n = 31) total cholesterol and low density lipoprotein cholesterol were significantly reduced [-0.24 mmol/liter, 3.8% (P = 0.015) and -0.33 mmol/liter, 8.2% (P = 0.004), respectively]. Low density lipoprotein cholesterol decrease was more pronounced in patients with TSH levels greater than 12 mIU/liter or elevated low density lipoprotein cholesterol levels at baseline. A significant decrease in apolipoprotein B-100 concentrations was observed (P = 0.037), whereas high density lipoprotein cholesterol, triglycerides, apolipoprotein AI, and lipoprotein(a) levels remained unchanged. Two clinical scores assessing symptoms and signs of hypothyroidism (Billewicz and Zulewski scores) improved significantly (P = 0.02). This is the first double blind study to show that physiological L-thyroxine replacement in patients with subclinical hypothyroidism has a beneficial effect on low density lipoprotein cholesterol levels and clinical symptoms of hypothyroidism. An important risk reduction of cardiovascular mortality of 9-31% can be estimated from the observed improvement in low density lipoprotein cholesterol.

A conformational switch controlling HIV-1 morphogenesis

Assembly of infectious human immunodeficiency virus type 1 (HIV-1) proceeds in two steps. Initially, an immature virus with a spherical capsid shell consisting of uncleaved Gag polyproteins is formed. Extracellular proteolytic maturation causes rearrangement of the inner virion structure, leading to the conical capsid of the infectious virus. Using an in vitro assembly system, we show that the same HIV-1 Gag-derived protein can form spherical particles, virtually indistinguishable from immature HIV-1 capsids, as well as tubular or conical particles, resembling the mature core. The assembly phenotype could be correlated with differential binding of the protein to monoclonal antibodies recognizing epitopes in the HIV-1 capsid protein (CA), suggesting distinct conformations of this domain. Only tubular and conical particles were observed when the protein lacked spacer peptide SP1 at the C-terminus of CA, indicating that SP1 may act as a molecular switch, whose presence determines spherical capsid formation, while its cleavage leads to maturation.

p53 Protein exhibits 3'-to-5' exonuclease activity

Highly purified p53 protein from different sources was able to degrade DNA with a 3'-to-5' polarity, yielding deoxynucleoside monophosphates as reaction products. This exonuclease activity was dependent on Mg2+ and inhibited by addition of 5 mM nucleoside monophosphates. This exonuclease activity is intrinsic to the wild-type p53 protein: it copurified with p53 during p53 preparation; only purified wild-type p53, but not identically purified mutant p53 proteins displayed exonuclease activity; the exonuclease activity could be reconstituted from SDS gel-purified and urea-renatured p53 protein and mapped to the core domain of the p53 molecule; and finally, purified p53 protein could be UV-cross-linked to GMP. A p53-intrinsic exonuclease activity should substantially extend our view on the role of p53 as a "guardian of the genome."

Incidence of Parkinson's disease in Norway: the Norwegian ParkWest study

OBJECTIVE

To present the incidence of Parkinson's disease (PD) in Norway and to explore gender influences on incidence and age at onset, as well as severity and pattern of parkinsonism at the time of diagnosis in a representative drug naïve cohort with newly diagnosed PD.

METHODS

In four Norwegian counties comprising a base population of 1 052 075 inhabitants, multiple sources of case ascertainment and a four step diagnostic procedure were used to establish a representative cohort of patients with incident PD at a high level of diagnostic accuracy. Of a total of 604 subjects referred to the study, 265 individuals fulfilled the clinical research criteria of PD at their latest clinical visit, at a mean 28 months after identification.

RESULTS

The incidence of PD in the study area, age standardised to the 1991 European standard population, was 12.6/10(5yr-1) (95% CI 11.1 to 14.2). The overall age standardised male to female ratio was 1.58 (95% CI 1.22 to 2.06), with a consistent male preponderance throughout all age groups. Clinical onset of PD was later in women than in men (68.6 vs 66.3 years; p = 0.062) whereas severity and pattern of parkinsonism in drug naïve patients was not different between genders at the time of diagnosis.

CONCLUSION

Incidence rates of PD in Norway are similar to those in other Western European and American countries. Female gender was associated with a considerably lower risk of PD and slightly delayed motor onset but had no impact on severity of parkinsonism or clinical phenotype in incident drug naïve PD, suggesting that the female gender influences on the nigrostriatal system are most pronounced in the preclinical phase of the disease.

Axonal guidance in the chick visual system: posterior tectal membranes induce collapse of growth cones from the temporal retina

Membranes from posterior and anterior thirds of the chick optic tectum were added to explants from nasal and temporal retina. Posterior membranes, and to a lesser extent anterior membranes, cause temporal growth cones to collapse and their axonal processes to retract. Neither tectal source has an effect on nasal growth cones. We interpret these results to mean that there is a tectal activity, stronger in the posterior than the anterior region of the tectum, which helps guide growth cones during the development of the retinotectal map. We believe that in vivo this activity helps to steer temporal growth cones away from the posterior tectum. Nasal growth cones, which must map to the posterior tectum, are resistant to it. In vitro, when posterior membranes contact temporal growth cones over their surface, filopodia and lamellipodia withdraw rapidly. This leads to loss of contact between the growth cone and the substrate, followed by collapse.

Biomarkers in respiratory tract infections: diagnostic guides to antibiotic prescription, prognostic markers and mediators

Used appropriately, biomarkers improve the assessment of respiratory tract infections and sepsis. Most prominently, circulating procalcitonin levels increase by a factor of several tens of thousands during sepsis. Using a sensitive assay, procalcitonin safely and markedly reduces antibiotic usage in respiratory tract infections and nonbacterial meningitis. Procalcitonin is the protopye of hormokine mediators. The term "hormokine" encompasses the cytokine-like behaviour of hormones during inflammation and infections. The concept is based on a ubiquitous expression of calcitonin peptides during sepsis. Adrenomedullin, another member of the calcitonin peptide superfamily, was shown to complement and improve the current prognostic assessment in lower respiratory tract infections. Other peptides share some features of hormokines, e.g. natriuretic peptide and copeptin. Hormokines are not only biomarkers of infection but are also pivotal inflammatory mediators. Like all mediators, their role during systemic infections is basically beneficial, possibly to combat invading microbes. However, at increased levels they can become harmful for their host. Multiple mechanisms of action were proposed. In several animal models the modulation and neutralisation of hormokines during infection was shown to improve survival, and thus might open new treatment options for severe infections, especially of the respiratory tract.

Reliability and interobserver variability in radiological patellar height ratios

This study evaluated the reliability and interobserver variability of five patellar height ratios as measured by two examiners on standard radiographs: Insall-Salvati (IS), modified Insall-Salvati (MIS), Blackburne-Peel (BP), Caton-Deschamps (CD), and Labelle-Laurin (LL). Plain lateral radiographs with a knee flexion angle of 20 degrees for IS, MIS, BP, and CD ratios and 90 degrees for the LL method of 22 knees of 21 patients with varying pathological knee conditions were analyzed. Statistical results revealed a low interobserver variability with high correlation coefficients (0.86 for IS, 0.82 for MIS, 0.86 for BP, 0.92 for CD, and 0.81 for LL; P > 0.3) and low mean interobserver errors. However, regarding the reliability of the radiographic results of the different methods for patella alta, baja, or norma we found varying results in 68% of the patients. In two patients the patellar height was classified as alta, norma, or baja depending on the ratio used. Regarding the definitions of patellar height used by the authors of these methods, we found the lowest number of normal patellae with the IS ratio and no patella alta for the CD ratio. The LL method revealed the highest number of patella alta. The BP ratio showed intermediate results for both patella alta and baja, being the most moderate method. This study showed that there was a good interobserver reliability for the evaluation of patellar height according to the common radiological ratios. However, the high frequency of differing results between the different radiographic ratios showed that patellar height classification as "alta," "norma," or "baja" depends heavily on the chosen index. The differing results were due mainly to the normative patellar height data and to anatomical differences. Based on these findings we recommend a ratio using the articular surface of the patella in relation to the joint line. We recommend the BP method because it revealed the lowest interobserver variability and discriminated best among the groups alta, norma, and baja.

Overweight and obesity in children with Attention-Deficit/Hyperactivity Disorder

OBJECTIVE

Epidemiological studies suggest that adiposity in children may be associated with a reduced level of physical activity. Children with Attention-Deficit/Hyperactivity Disorder (ADHD) are physically hyperactive as of early childhood and have been shown to exhibit higher levels of motor activity than normal. The aim of our study was to assess if the prevalence of overweight and obesity is lower in a population of boys with ADHD in comparison with the German healthy male reference population of the same age.

DESIGN

Patients were investigated from 1999 until 2001 upon referral to the inpatient and outpatient unit of the Department of Child and Adolescent Psychiatry of the University of Aachen.

SUBJECTS

A total of 97 male patients (mean age 10+/-2 y) with a diagnosis of ADHD according the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), who were free of potentially orexigenic medication and who had no further comorbid diagnosis apart from conduct disorder.

MEASUREMENTS

BMI standard deviation scores (BMI-SDS) were calculated and compared to age-adapted reference value of the German population.

RESULTS

Patients' mean BMI-SDS was significantly higher than the age-adapted reference values of the German population (P=0.038). Our sample included significantly more subjects than expected with a BMI > or =90th percentile (19.6%, P<0.001) and > or =97th percentile (7.2%, P=0.007).

CONCLUSION

Surprisingly, being 'hyperactive' in the sense of the DSM-IV diagnosis of ADHD does not prevent the development or persistence of overweight and obesity in children. The examination of these children might be a helpful approach in the investigation of the relationship between obesity and its contributing psychological and behavioural factors.

Increased angiotensin-I converting enzyme gene expression in the failing human heart. Quantification by competitive RNA polymerase chain reaction

Local activation of the components of the renin angiotensin system in the heart is regarded as an important modulator of cardiac phenotype and function; however, little is known about their presence, regulation, and potential activation in the human heart. To investigate the gene expression of major angiotensin-II-forming enzymes in left ventricles of normal (n = 9) and failing human hearts (n = 20), we established a competitive RNA-polymerase chain reaction (PCR) for mRNA quantification of angiotensin-I converting enzyme (ACE) and human heart chymase. For each gene, competitor RNA targets with small internal deletions were used as internal standards to quantify the original number of transcripts and to control reverse transcription and PCR. In PCR, each target and the corresponding competitor were amplified by competing for the same primer oligonucleotides. The variability of ACE RNA-PCR was 11% indicating a high reproducibility of this method. In addition, ACE mRNA levels obtained by competitive RNA-PCR correlated favorably with traditional slot blot hybridization (r = 0.69, n = 10; P < 0.05). Compared with nonfailing hearts, the number of ACE transcripts referred to 100 ng of total RNA was increased threefold in patients with chronic heart failure (4.2 +/- 2.5 vs. 12.8 +/- 6 x 10(5); P < 0.0005). In contrast, no significant difference was found in chymase gene expression between normal and failing hearts. Thus, the expression of the cardiac ACE but not of human heart chymase is upregulated in failing human heart indicating an activation of the cardiac renin-angiotensin system in patients with advanced heart failure.

Circulating levels of copeptin, a novel biomarker, in lower respiratory tract infections

BACKGROUND

Vasopressin has haemodynamic as well as osmoregulatory effects, and reflects the individual stress response. Copeptin is co-synthesized with vasopressin, directly mirroring vasopressin levels, but is more stable in plasma and serum. Both levels are increased in patients with septic shock. Lower respiratory tract infections (LRTI) are a precursor of sepsis. Thus, we investigated circulating levels and the prognostic use of copeptin for the severity and outcome in patients with LRTI.

MATERIALS AND METHODS

Five hundred and forty-five consecutive patients with LRTI and 50 healthy controls were evaluated. Serum copeptin levels were measured with a new chemiluminescent sandwich immunoassay.

RESULTS

Of the 545 patients, 373 had community-acquired pneumonia (CAP), 60 acute exacerbations of chronic obstructive pulmonary disease (COPD), 59 acute bronchitis, 13 exacerbations of asthma and 40 other final diagnoses. Copeptin levels were significantly higher in patients with LRTI as compared to controls (P < 0.001) with highest levels in patients with CAP. Copeptin levels increased with increasing severity of CAP, as classified by the pneumonia severity index (PSI) (P < 0.001). In patients who died, copeptin levels on admission were significantly higher as compared to levels in survivors [70.0 (28.8-149.0) vs. 24.3 (10.8-43.8) pmol L(-1), P < 0.001]. The area under the receiver operating curve (AUC) for survival was 0.75 for copeptin, which was significantly higher as compared to C-reactive protein (AUC 0.61, P = 0.01), leukocyte count (AUC 0.59, P = 0.01) and similar to procalcitonin (AUC 0.68, P = 0.21).

CONCLUSIONS

Copeptin levels are increased with increasing severity of LRTI namely in patients with CAP and unfavourable outcome. Copeptin levels, as a novel biomarker, might be a useful tool in the risk stratification of patients with LRTI.

Ubiquitous expression of the calcitonin-i gene in multiple tissues in response to sepsis

Calcitonin precursors (CTpr), including procalcitonin, are important markers and also potentially harmful mediators in response to microbial infections. The source and function of CTpr production in sepsis, however, remains an enigma. In the classical view, the transcription of the CT-I gene is restricted to neuroendocrine cells, in particular the C cells of the thyroid. To better understand the pathophysiology of CTpr induction in sepsis, we used an animal model analog to human sepsis, in which bacterial infection is induced in hamsters by implanting Escherichia coli pellets ip. Compared with control hamsters, levels of CTpr were elevated several fold in septic plasma and in nearly all septic hamster tissues analyzed. Unexpectedly, CT-messenger RNA was ubiquitously and uniformly expressed in multiple tissues throughout the body in response to sepsis. Notably, the transcriptional expression of CT-messenger RNA seemed more widely up-regulated in sepsis than were classical cytokines (e.g. tumor necrosis factor-alpha and interleukin-6). Our findings, which describe a potentially new mechanism of host response to a microbial infection mediated by CTpr, introduce a new pathophysiological role for the CT-I gene.

The gene for histone RNA hairpin binding protein is located on human chromosome 4 and encodes a novel type of RNA binding protein

The hairpin structure at the 3' end of animal histone mRNAs controls histone RNA 3' processing, nucleocytoplasmic transport, translation and stability of histone mRNA. Functionally overlapping, if not identical, proteins binding to the histone RNA hairpin have been identified in nuclear and polysomal extracts. Our own results indicated that these hairpin binding proteins (HBPs) bind their target RNA as monomers and that the resulting ribonucleoprotein complexes are extremely stable. These features prompted us to select for HBP-encoding human cDNAs by RNA-mediated three-hybrid selection in Saccharomyces cerevesiae. Whole cell extract from one selected clone contained a Gal4 fusion protein that interacted with histone hairpin RNA in a sequence- and structure-specific manner similar to a fraction enriched for bovine HBP, indicating that the cDNA encoded HBP. DNA sequence analysis revealed that the coding sequence did not contain any known RNA binding motifs. The HBP gene is composed of eight exons covering 19.5 kb on the short arm of chromosome 4. Translation of the HBP open reading frame in vitro produced a 43 kDa protein with RNA binding specificity identical to murine or bovine HBP. In addition, recombinant HBP expressed in S. cerevisiae was functional in histone pre-mRNA processing, confirming that we have indeed identified the human HBP gene.

Synthesis, anticonvulsant activity, and structure-activity relationships of sodium channel blocking 3-aminopyrroles

Starting from the corresponding acetophenone and glycine derivatives, a series of new 3-aminopyrroles was synthesized in few steps. Using this procedure with hydrazine and hydroxylamine instead of the glycinates provides access to 3-aminopyrazoles and 5-amino 1,2-oxazoles. The various derivatives were tested for anticonvulsant activity in a variety of test models. Several compounds exhibit considerable activity with a remarkable lack of neurotoxicity. 4-(4-Bromophenyl)-3-morpholinopyrrole-2-carboxylic acid methyl ester, 3, proved to be the most active compound. It was protective in the maximal electroshock seizure (MES) test in rats with an oral ED50 of 2.5 mg/kg with no neurotoxicity noted at doses up to 500 mg/kg. Compound 3 blocks sodium channels in a frequency-dependent manner. The essential structural features which could be responsible for an interaction with an active site of the voltage-dependent sodium channel are established within a suggested pharmacophore model.

RuvA and RuvB proteins of Escherichia coli exhibit DNA helicase activity in vitro

The SOS-inducible ruvA and ruvB gene products of Escherichia coli are required for normal levels of genetic recombination and DNA repair. In vitro, RuvA protein interacts specifically with Holliday junctions and, together with RuvB (an ATPase), promotes their movement along DNA. This process, known as branch migration, is important for the formation of heteroduplex DNA. In this paper, we show that the RuvA and RuvB proteins promote the unwinding of partially duplex DNA. Using single-stranded circular DNA substrates with annealed fragments (52-558 nucleotides in length), we show that RuvA and RuvB promote strand displacement with a 5'-->3' polarity. The reaction is ATP-dependent and its efficiency is inversely related to the length of the duplex DNA. These results show that the ruvA and ruvB genes encode a DNA helicase that specifically recognizes Holliday junctions and promotes branch migration.

CD14, new aspects of ligand and signal diversity

The glycosyl-phosphatidylinositol-linked glycoprotein CD14 is expressed in myeloid cells and serum. It binds Gram-negative and -positive bacterial cell wall components and endogenous phospholipids. Toll-like receptors, NF-kappaB and MAP kinases participate in CD14 signaling of inflammation. Alterations of CD14 in inflammatory diseases support a pathogenic role for this microbial receptor.