bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antibiotics that inhibit cell wall biosynthesis induce expression of the Bacillus subtilisσW and σM regulons
Authors: Cao Min , Wang Tao , Ye Rick , Helmann John D. 
Published: March 2003

Summary Bacillus subtilis
encodes seven extracytoplasmic function (ECF) sigma factors. The
σ
W
regulon includes functions involved in detoxification and protection against antimicrobials, whereas
σ
M
is essential for growth at high salt concentrations. We now report that antibiotics that inhibit cell wall biosynthesis induce both
σ
W
and
σ
M
regulons as monitored using DNA microarrays. Induction of selected
σ
W
‐dependent genes was confirmed using
lacZ
reporter fusions and Northern blot analysis. The ability of vancomycin to induce the
σ
W
regulon is dependent on both
σ
W
and the cognate anti‐
σ
, RsiW, but is independent of the transition state regulator AbrB. These results suggest that the membrane‐localized RsiW anti‐
σ
W
factor mediates the transcriptional response to cell wall stress. Our findings are consistent with the idea that one function of ECF
σ factors is to coordinate antibiosis stress responses and cell envelope homeostasis.
Large‐scale identification of serotype 4 Streptococcus pneumoniae virulence factors
Authors: Hava David L. , Camilli Andrew 
Published: March 2003

Summary Streptococcus pneumoniae
(the pneumococcus) is carried in the nasopharynx of healthy individuals, but can spread to other host sites and lead to pneumonia, bacteraemia, otitis media and meningitis. Although it is logical to think
a priori
that differential gene expression would contribute to the ability of this patho­‐gen to colonize different sites, in fact very few genes have been demonstrated to play tissue specific roles in virulence or carriage. Using signature‐tagged mutagenesis to screen 6149
mariner ‐transposon insertion strains, we identified 387 mutants attenuated for infection in a murine model of pneumonia. Among these mutants are ones with disruptions in a number of putative tissue‐specific transcriptional regulators, surface proteins, metabolic proteins and proteins of unknown function, most of which had not previously been associated with virulence. A subset of these, including most of those with insertions in putative transcriptional regulators, was examined for phenotypes in murine models of bacteraemia and nasopharyngeal carriage. Four classes of mutants defective in infection models of the: (I) lung, (II) lung and blood, (III) lung and nasopharynx, and (IV) all three tissues were identified, thus demonstrating the ex­‐istence of tissue‐specific pneumococcal virulence factors. Included in these strains were two with ­disruptions in a genetic locus that putatively codes for a transcriptional regulator, three surface proteins and three sortase homologues. Mutation analysis revealed that three of the seven genes in this locus are virulence factors that are specific to mucosal ­surfaces.
Two transcriptional regulators GlnR and GlnRII are involved in regulation of nitrogen metabolism in Streptomyces coelicolor A3(2)
Authors: Fink D. , Weißschuh N. , Reuther J. , Wohlleben W. , Engels A. 
Published: March 2003

SummaryStreptomyces coelicolor
has an unusually large arsenal of glutamine synthetase (GS) enzymes: a prokaryotic GSI‐β‐subtype enzyme (encoded by
glnA
), three annotated
glnA
‐like genes of the GSI‐α‐subtype and a eukaryote‐like glutamine synthetase II (encoded by
glnII
). Under all tested conditions, GSI was found to represent the dominant glutamine synthetase activity. A significant heat‐labile GSII activity, which is very low to undetectable in liquid‐grown cultures, was only detected in morphologically differentiating
S. coelicolor
cultures. Analysis of
glnA
and
glnII
transcription by S1 nuclease mapping and
egfp
fusions revealed that, on nitrogen‐limiting solid medium,
glnII
but not
glnA
expression is upregulated. An OmpR‐like regulator protein, GlnR, has previously been implicated in transcriptional control of
glnA
expression. Gel retardation analysis revealed that GlnR is a DNA‐binding protein, which interacts with the
glnA
promoter. It is not autoregulatory and does not bind to the upstream regions of the
glnA
‐like genes of the α‐subfamily, nor to the
glnII
promoter
in vitro
. A second GlnR target was identified upstream of the
amtB
gene, encoding a putative ammonium transporter.
amtB
forms an operon with
glnK
(encoding a PII protein) and
glnD
(encoding a putative PII nucleotidylyltransferase) shown by S1 nuclease protection analysis and reverse transcription‐polymerase chain reaction (RT‐PCR). An
amtB
and
glnA
promoter alignment revealed a putative GlnR operator structure. Downstream of
glnII
, a gene encoding for another OmpR‐like regulator, GlnRII, was identified, with strong similarity to GlnR. Gel shifts with GlnRII showed that the promoters recognized by GlnR are also targets of GlnRII. However, GlnRII also interacted with the
glnII
upstream region. Only inactivation of
glnR
resulted in a glutamine auxotrophic phenotype, whereas the
glnRII mutant can grow on minimal medium without glutamine.
Modular domain structure in the Candida glabrata adhesin Epa1p, a β1,6 glucan‐cross‐linked cell wall protein
Authors: Frieman Matthew B. , McCaffery J. Michael , Cormack Brendan P. 
Published: March 2003

SummaryThe yeast pathogen Candida glabrata adheres avidly to cultured human epithelial cells. This interaction depends on the expression of EPA1, which encodes a lectin belonging to a large family of GPI‐anchored glucan‐cross‐linked cell wall proteins (GPI‐CWPs) found in diverse fungal species. To understand the relationship between different domains of EPA1 and its function, we have mapped functional domains of Epa1p and analysed their contribution to Epa1p function. We found that the N‐terminal third of the protein contains the ligand‐binding domain, and that the GPI anchor is essential both for cross‐linking in the cell wall and for Epa1p‐mediated adherence. We also found that the C‐terminal Ser/Thr‐rich domain, characteristic of many GPI‐CWPs, was absolutely essential for function. Although Epa1p derivatives lacking the Ser/Thr domain were expressed abundantly in the cell wall, they were localized to internal layers of the cell wall; such constructs were unable to mediate adherence. The outer layer of the yeast cell wall is known to act as a permeability barrier; we found that the C‐terminal Ser/Thr‐rich region was absolutely required to project the N‐terminal domain of Epa1p through this permeability barrier and into the external environment. Thus, the Ser/Thr‐rich domain of Epa1p and, presumably, of other related GPI‐CWPs serves an essential structural role in localization of the protein at the external surface of the yeast cell where it can interact with its ligand. In conclusion, Epa1p has a modular structure, with each domain serving a distinct and essential role in the function of the adhesin.
The transcriptional response to alkaline pH in Saccharomyces cerevisiae: evidence for calcium‐mediated signalling
Authors: Serrano Raquel , Ruiz Amparo , Bernal Dolores , Chambers James R. , Ariño Joaquín 
Published: March 2003

SummaryThe short‐time transcriptional response of yeast cells to a mild increase in external pH (7.6) has been investigated using DNA microarrays. A total of 150 genes increased their mRNA level at least twofold within 45 min. Alkalinization resulted in the repression of 232 genes. The response of four upregulated genes, ENA1 (encoding a Na+‐ATPase also induced by saline stress) and PHO84, PHO89 and PHO12 (encoding genes upregulated by phosphate starvation), was characterized further. The alkaline response of ENA1 was not affected by mutation of relevant genes involved in osmotic or oxidative signalling, but was decreased in calcineurin and rim101 mutants. Mapping of the ENA1 promoter revealed two pH‐responsive regions. The response of the upstream region was fully abolished by the drug FK506 or mutation of CRZ1 (a transcription factor activated by calcium/calcineurin), whereas the response of the downstream region was essentially calcium independent. PHO84 and PHO12 responses were unaffected in crz1 cells, but required the presence of Pho2 and Pho4. In contrast, part of the alkali‐induced expression of PHO89 was maintained in pho4 or pho2 cells, but was fully abolished in a crz1 strain or in the presence of FK506. Heterologous promoters carrying the minimal calcineurin‐dependent response elements found in ENA1 or FKS2 were able to drive alkaline pH‐induced expression. These results demonstrate that the transcriptional response to alkaline pH involves different signalling mechanisms, and that calcium signalling is a relevant component of this response.
Genome plasticity in Acinetobacter: new degradative capabilities acquired by the spontaneous amplification of large chromosomal segments
Authors: Reams Andrew B. , Neidle Ellen L. 
Published: March 2003

SummaryIn Acinetobacter sp. ADP1, growth on benzoate requires regulation of the cat genes by two transcriptional activators. Here, mutants were obtained from a strain lacking both activators by selecting for growth on benzoate medium. The mutants, which arose within 3 weeks at a frequency of approximately 10−8, carried amplified chromosomal regions (amplicons) encompassing the cat genes. Multiple occurrences of low‐level expression of catA and the catBCIJFD operon provided sufficient transcription for growth. The amplicons of four independently isolated mutants varied in size from approximately 30–100 kbp of the normally 3.8 Mbp chromosome. Mutants had approximately 10–20 copies of an amplicon in adjacent head‐to‐tail orientations. At the amplicon's chromosomal endpoint, an atypical junction juxtaposed normally distant DNA regions from opposite sides of the cat genes. The sequences of these junctions revealed the precise recombination sites underlying amplification. Additionally, amplicon stability was evaluated in the absence of selective pressure. The natural competence of Acinetobacter for transformation by linear DNA has allowed the development of a powerful new model system for investigating chromosomal rearrangements and for engineering DNA amplifications for wide‐ranging applications. The frequent spontaneous amplification of these large chromosomal segments demonstrated the importance of supra‐operonic gene clustering in the evolution of catabolic pathways.
The 13C‐octanoic acid breath test: validation of a new noninvasive method of measuring gastric emptying in rats
Authors: Schoonjans R. , Van Vlem B. , Van Heddeghem N. , Vandamme W. , Vanholder R. , Lameire N. , Lefebvre R. , De Vos M. 
Published: March 2003

Abstract

Currently available rat models for measuring gastric emptying are hampered by the necessity to kill the animals at the end of each experiment, which makes repetitive testing impossible. We have developed and validated a noninvasive test model, adapted from the13C‐octanoic breath test in humans, for repetitive measurements of gastric emptying in rats. Male Wistar rats were trained on a fixed protocol to eat a piece of pancake doped with 1 μg13C‐octanoic acid after 12 h fasting, and to stay thereafter in cylindrical glass cages. Breath tests were performed by a fully automated system of computer‐guided switching valves, which collected consecutive breath samples. All breath samples were analysed by gas chromatography and isotope mass spectrometry. The area under the curve (AUC) from the cumulative13CO2excretion from 0 to 6 h was determined by the trapezium method to calculate the gastric half‐emptying times (t½). Inter‐day variability was determined. The effect of subcutaneous or intraperitoneal injection of saline was studied. The test was further validated for pharmacological interventions by oral administration of cisapride and parenteral administration of atropine, to induce, respectively. acceleration and delay of gastric emptying. Mean gastric emptying times ± SD of 24 rats were 119.3 ± 28.2 min, 138.7 ± 26.0 min, and 124.5 ± 30.9 min on three different test days. The mean coefficient of variation of three repeated measurements in the same 24 rats was 17.5%. No significant differences were observed after subcutaneous or intraperitoneal injection of saline. In a second test series of eight rats, cisapride significantly accelerated gastric emptying (mean t½ 112.7 ± 33.1 min, P < 0.05), while atropine caused a significant delay (mean t½ 205.9 ± 24.9 min, P < 0.05) when compared to control test results (mean t½ 140.7 ± 16.7 min) in the same rats. We validated the13C‐octanoic breath test to study gastric emptying in rats. This test method obviates the necessity to kill laboratory animals and allows repetitive measurements of gastric emptying to study its physiology or pathophysiology as well as the effect of pharmacological agents.
Influence of naloxone on gastric emptying of solid meals, myoelectrical gastric activity and blood hormone levels in young healthy volunteers
Authors: Reber P. U. , Netzer P. , Gaia C. , Wildi S. , Lourens ST. , Noelpp U. , Lüscher D. , Varga L. , Brenneisen R. , Scheurer U. 
Published: March 2003

Abstract
There is considerable evidence that opioid mechanisms are involved in the mediation of pyloric motor responses that in turn regulate gastric emptying. The purpose of this randomized, placebo‐controlled crossover study was to investigate the effect of naloxone on gastric emptying of a solid meal, gastric myoelectrical activity and the postprandial release of gastrointestinal peptides and neuropeptides in 20 healthy volunteers. Naloxone was administered as an intravenous bolus, followed by continuous infusion according to an intravenous dosing nomogram. Gastric emptying time was evaluated by scintigraphy and gastric myoelectrical activity was evaluated by cutaneous electrogastrography. Naloxone did not significantly alter gastric half‐emptying time and postprandial dominant gastric electrical frequency compared with placebo. It also did not significantly change the plasma levels of several peptide hormones with the exception of neuropeptide Y, which was significantly increased (P = 0.001). In conclusion, in doses that influence human intestinal motility, naloxone had no effect on gastric motility and release of several peptide hormones in healthy male volunteers. The importance of the isolated increased neuropeptide Y plasma level needs further investigation.
Do quantitative or qualitative histological changes occur in the premotor substrate for vertical gaze as a function of ageing?
Authors: Henson C. , Staunton H. , Brett F. M. 
Published: March 2003

Introduction:  Currently, there is debate in the clinical literature as to whether defects in vertical gaze occur as a consequence of normal ageing or a component of an underlying neurodegenerative disorder (Waite et al. Arch Neurol 1996; 53: 498). Although pathological changes have been demonstrated in diseased subjects (Brett et al. Arch Neurol 2001 in press), no study to date has addressed the question of normal ageing effects. The goal of our study was qualitatively and quantitatively to investigate histological changes in the primary premotor substrate of vertical gaze in young and aged subjects.Subjects and methods:  Twenty‐three subjects were chosen from a group of 52 neurologically and pathologically normal subjects, ages 18–91. Using an unbiased, frame‐based sampling method (Gundersen et al. J Microscopy 1977; 111: 219–222), we quantified neuronal and glial cell densities in 10 young (<50 years old) and 13 aged (>65 years old) subjects in the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF), i.e. the key premotor substrate in the vertical gaze pathway.Results:  We found no statistically significant difference in neuronal density (P ≥ 0.05), glial cell density (P ≥ 0.05) or neuron‐to‐glial cell ratios (P ≥ 0.05) between the young and the aged subjects.Conclusion:  Our results support the conclusion that neuronal loss, neuronal atrophy or gliosis in the riMLF are not consequences of normal ageing.
Atypical pituitary adenoma (silent corticotroph pituitary adenoma)
Authors: Al‐Sarraj S. , King A. , Harris P. , Lantos P. 
Published: March 2003

Introduction:  Pituitary adenomas are benign neoplasms with clinical behaviour and recurrence depending on the size of the tumour, therefore it is more common in nonfunctioning macroadenoma adenomas.Material and methods:  Patient 1: A 40‐year female presented originally with visual field disturbance and underwent transphenoidal resection of pituitary macroadenoma in 1995. The tumour recurred in 1997 and 1998. Despite aggressive radiotherapy, the tumour metastasized to the vertebra in 1999. Patient 2: A 46‐year female presented with clinically nonfunctioning pituitary macroadenoma. She required two transphenoidal operations in 1998 and 1999, and underwent radiotherapy.Results:  Patient 1: The initial biopsy shows silent corticotroph pituitary adenoma with occasional mitotic figures and Ki67 labelling index 2%. The recurrences in 1997 and 1998 showed increased nuclear pleomorphism, mitotic activity and Ki67 labelling (5% and 8%). The p53 was positive. The metastatic deposit in the vertebra showed similar histology but with Ki67 labelling of 15% and p53 immunoreactivity of 10%. Patient 2: The initial biopsy in 1998 showed silent corticotroph adenoma with Ki67 of 1%. The recurrence in 1999 showed increased mitotic figure, Ki67 labelling of 5% and p53 immunoreactivity.Conclusion:  Silent corticotroph adenoma could be regarded as atypical pituitary adenoma with aggressive behaviour and high recurrence rate.
Neuropathology of septic shock
Authors: Gray F. , Sharshar T. , De La Grandmaison G. Lorin , Annane D. 
Published: March 2003

Introduction:  Septic shock is the most frequent cause of death in intensive care units. It is often complicated by an encephalopathy and there is increasing evidence that central autonomic nervous system (CANS) dysfunction plays a crucial role in the onset and persistance of the haemodynamic failure. However, only a few neuropathological studies are available; they are always retrospective and often disagree.Material and methods:  Twenty consecutive patient who died from septic shock were examined and compared with eight patients who died from nonseptic shock in the same unit and five ‘normal’ controls collected from the Forensic Medicine Service.Results and conclusion:  A variety of lesions, including microabscesses, multifocal necrotizing leukoencephalopathy, haemorrhages and disseminated intravascular coagulation, were found, and were most probably related to the biological disturbances associated with sepsis. These lesions may contribute to the ‘septic encephalopathy’. Ischaemic changes in ‘susceptible’ areas were comparable in septic shock and in nonseptic shock. In contrast, ischaemic changes in the nuclei of the CANS were significantly more severe in septic shock than in nonseptic shock. Neuronal apoptosis in these nuclei was significantly more frequent and more severe in septic shock; apoptosis did not correlate exactly with neuronal ischaemia and was associated with only mild microglial activation suggesting that circulating factors may also play a role in its causation.
Differential neuronal responses between brain nuclei after blunt head‐injury
Authors: Mitchell Y. , Pennington K. , Maxwell W. , Graham D. I. 
Published: March 2003

Introduction:  Stereological evidence for loss of neurons after human blunt head‐injury is lacking. A quantitative analysis of total numbers of neurons in two different brain regions in nonhead‐injured control (n = 10) and severely head‐injured patients (n = 24) (age range 18–64) was undertaken.Material and methods:  8 µm paraffin sections of the left and right thalami and of the left hippocampus from all patients were cut and cresyl violet stained. The neuronal size in subfields of the hippocampus, and dorsomedial, lateral and ventral thalamic nuclei was measured to determine the size of the counting box and, within this, the total number of neurons was counted. Statistical analysis used the Student's t‐test.Results:  At 1 week, pyramidal neurons were lost from hippocampal subfields CA1 (P = 0.012), CA3 (P = 0.003) and CA4 (P = 0.002), but not from CA2. Further loss occurred at 6 months but only in CA1 (P = 0.033) and CA4 (P = 0.013). No evidence for loss of neurons from any thalamic nucleus was obtained.Conclusions:  Loss of neurons from different nuclei of the brain after blunt head‐injury occurs both with a different timescale and to a different extent. Anecdotal evidence of damage to thalamic nuclei after head‐injury has not been supported using stereology.
Influence of ApoE genotype on cerebral amyloid angiopathy after closed head‐injury
Authors: Leclercq P. D. , Graham D. I. , Nicoll J. A. R. , Gentleman S. M. 
Published: March 2003

Introduction:  Possession of an ε4 allele of the apolipoprotein E gene is a recognized genetic risk factor for Alzheimer's disease but has also been linked to traumatic brain injury, dementia pugilistica, cerebrovascular diseases and stroke.Materials and methods:  In this study, we have combined morphological and quantitative analysis to investigate the effect of the genotype on the pathology observed after fatal closed head‐injury in a cohort of 88 patients.Results:  Quantification of the amyloid‐β (Aβ) pathology in these cases has confirmed the original qualitative observations made by Nicoll et al. (Nat Medicine 1995) that the amount of Aβ pathology correlates with the ε4 gene dose. More striking, however, was the fact that the presence of cerebral amyloid angiopathy (CAA) was very strongly associated with the possession of the ε4 allele. Seven out of eight cases with CAA were ε4 carriers and half of them were ε4 homozygotes.Conclusion:  Over the total HI cohort, ε4 carriers had 8.75 times more chance of developing CAA after brain trauma than non‐ε4 carriers.