bluuebunny/crossref_metadata_2025_split huggingface dataset:
A conserved region within the Bordetella pertussis autotransporter BrkA is necessary for folding of its passenger domain
Authors: Oliver David C. , Huang George , Nodel Elena , Pleasance Steve , Fernandez Rachel C. 
Published: March 2003

SummaryAutotransporter secretion represents a unique mechanism that Gram‐negative bacteria employ to deliver proteins to their cell surface. BrkA is a Bordetella pertussis autotransporter protein that mediates serum resistance and contributes to adherence of the bacterium to host cells. BrkA is a 103 kDa protein that is cleaved to form a 73 kDa α‐domain and a 30 kDa β domain. The α domain, also referred to as the passenger domain, is responsible for the effector functions of the protein, whereas the β domain serves as a transporter. In an effort to characterize BrkA secretion, we have shown that BrkA has a 42 amino acid signal peptide for transit across the cytoplasmic membrane, and a translocation unit made up of a short linker region fused to the β‐domain to ferry the passenger domain to the bacterial surface through a channel formed by the β‐domain. In this report, we provide genetic, biochemical and structural evidence demonstrating that a region within the BrkA passenger (Glu601–Ala692) is necessary for folding the passenger. This region is not required for surface display in the outer membrane protease OmpT‐deficient Escherichia coli strain UT5600. However, a BrkA mutant protein bearing a deletion in this region is susceptible to digestion when expressed in E. coli strains expressing OmpT suggesting that the region is required to maintain a stable structure. The instability of the deletion mutant can be rescued by surface expressing Glu601–Ala692in trans suggesting that this region is acting as an intramolecular chaperone to effect folding of the passenger concurrent with or following translocation across the outer membrane.
Tn5 as a model for understanding DNA transposition
Authors: Reznikoff William S. 
Published: March 2003

SummaryTn5 is an excellent model system for understanding the molecular basis of DNA‐mediated transposition. Mechanistic information has come from genetic and biochemical investigations of the transposase and its interactions with the recognition DNA sequences at the ends of the transposon. More recently, molecular structure analyses of catalytically active transposase; transposon DNA complexes have provided us with unprecedented insights into this transposition system. Transposase initiates transposition by forming a dimeric transposase, transposon DNA complex. In the context of this complex, the transposase then catalyses four phosphoryl transfer reactions (DNA nicking, DNA hairpin formation, hairpin resolution and strand transfer into target DNA) resulting in the integration of the transposon into its new DNA site. The studies that elucidated these steps also provided important insights into the integration of retroviral genomes into host DNA and the immune system V(D)J joining process. This review will describe the structures and steps involved in Tn5 transposition and point out a biologically important although surprising characteristic of the wild‐type Tn5 transposase. Transposase is a very inactive protein. An inactive transposase protein ensures the survival of the host and thus the survival of Tn5.
Anorectal functions in patients with spinal cord injury
Authors: GREVING  , TEGENTHOFF  , NEDJAT  , ORTH  , BÖTEL  , MEISTER  , MICKLEFIELD  , MAY  , ENCK  
Published: March 2003

We wished to establish anorectal functions in patients with spinal cord lesions, related to the level of lesion and its completeness. We also wished to determine the value of neurophysiological tests for completeness of transsections in comparison with manometry and visceral sensory testing.In 32 patients (31.5 ± 14.1 years, 25 males) with spinal trauma, completeness of transsection was assessed clinically. In 16 of these patients (30 ± 15.6 years, nine males), a neurological work‐up included recording of somatosensory evoked potentials (SEP) and motor evoked potentials (MEP) from the pudendal nerve within the first week after trauma. Also, anal sphincter EMG and pudendal nerve terminal motor latency (PNTML) were assessed. All patients also underwent conventional anorectal manometry and visceral sensory testing.Of all 32 patients, 15 were judged as `complete' based on their clinical signs. Of those 16 tested neurologically, seven were labelled `complete' since no MEP or SEP were detectable; one had pudendal SEP and MEP present, while SEP were present but delayed (47.0 ± 8.8 msec) in the remaining patients. In four of these patients, also MEP were recorded (27.9 ± 5.2 msec) and normal. PNTML was present in 12/16 patients independent of the completeness of lesion, and was rated normal in nine and delayed in three patients. EMG was normal in five, and pathological in 11 cases. In 5/15 cases of those judged as `complete' (in 3/7 evaluated neurologically), visceral sensory testing revealed a minimal threshold for rectal perception of distension of 44 mL (range: 10–130), which sometimes was also perceived as urge to defecate. In a further case, manometry showed major voluntary action of the anal sphincter. These patients had lesions at all levels of the spinal column, ranging from cervical (C4,C6,C7) via thoratical (2 × T7,T8,T12) to lumbar segments.Anorectal function testing, and specifically visceral sensory testing may be superior to neurological assessment of `completeness' of spinal cord lesions. It may be that visceral afferent pathways others than spinothalamic tract are involved in rectal perception that are less accessible to conventional neurophysiological diagnostic work‐up.
Effect of the selective serotonin reuptake inhibitor sertraline on gastric sensitivity and compliance in healthy humans1
Authors: Ladabaum U , Glidden D 
Published: March 2003

Abstract
Visceral hypersensitivity may contribute to symptoms in functional dyspepsia. Selective serotonin reuptake inhibitors (SSRIs) may be beneficial in functional gastrointestinal disorders. The aim of this study was to determine whether the SSRI sertraline affects gastric sensitivity and compliance in healthy humans. Ten healthy humans completed a 6‐week randomized, double‐blind, crossover trial of sertraline (50 mg day−1) vs. placebo. After each 2‐week treatment, fullness, pain and nausea were rated at increasing gastric barostat distending pressures. Sensation thresholds above minimal distending pressure (MDP) were determined with a tracking method. Somatic sensory testing was performed by hand immersion in ice water. No differences were found between sertraline and placebo for symptoms as a function of distending pressure (fullness, P = 0.72; pain, P = 0.79; nausea, P = 0.41), gastric compliance (P = 0.15), median and interquartile range thresholds for first sensation [4.1 (3.5–5.7) vs. 6.2 (3.3–10.0) mmHg above MDP, P = 0.19] and pain [15.2 (8.3–21.0) vs. 15.3 (10.3–19.8) mmHg above MDP, P = 0.85], and median tolerance times for hand ice water immersion [27 (19–99) vs. 29 (20–180) s, P = 0.73]. In conclusion, sertraline had no effect on gastric sensitivity or compliance, or somatic pain tolerance in healthy humans. Studies are needed to assess the effects of SSRIs on visceral sensation and clinical symptoms in patients with functional dyspepsia.
Subdiaphragmatic vagal afferent innervation in activation of an opioidergic antinociceptive system in response to colorectal distension in rats
Authors: Gschossmann J. M. , Mayer E. A. , Miller J. C. , Raybould H. E. 
Published: March 2003

Abstract
In a number of different experimental paradigms of somatic pain, there is evidence for a vagally mediated antinociceptive system. This pathway probably involves opioid mechanisms. However, whether this pathway is activated in visceral pain or if it involves subdiaphragmatic vagal afferents is unclear. The aim of the present study was to determine whether subdiaphragmatic vagal afferents mediate antinociception in response to a visceral stimulus and whether this involves an opioid pathway. Colorectal distension was performed in fasted, conscious male Sprague–Dawley rats using a balloon catheter connected to an electronic distension device. The number of abdominal contractions (visceromotor response) in response to a tonic colorectal distension (60 mmHg for 10 min) was recorded. Experiments were performed in sham or subdiaphragmatically vagotomized, perineural vehicle‐ or capsaicin‐treated rats (to functionally denervate vagal afferents) before and after administration of naloxone (25 mg kg−1bodyweight intraperitoneally). Vagotomy, capsaicin and naloxone pretreatments all significantly enhanced the visceromotor response to colorectal distension. The effect of naloxone in capsaicin‐treated rats did not appear to be additive. These results suggest that activation of subdiaphragmatic afferents, which can be blocked by capsaicin, may play a role in opioid‐dependent antinociceptive pathways activated by a noxious visceral stimulus.
Distinct patterns of oesophageal shortening during primary peristalsis, secondary peristalsis and transient lower oesophageal sphincter relaxation
Authors: Shi G. , Pandolfino J. E. , Joehl R. J. , Brasseur J. G. , Kahrilas P. J. 
Published: March 2003

Abstract
This study characterized oesophageal shortening during secondary peristalsis and transient lower oesophageal sphincter relaxation (TLOSR) in an attempt to determine its contribution to the opening mechanism. Eight healthy subjects (four males, 26 ± 1 years) had metal clips affixed at 0, +3, and +8 cm relative to the squamocolumnar junction (SCJ), defining two distal oesophageal segments. Axial clip movement was assessed with concurrent videofluoroscopy and manometry during primary peristalsis, secondary peristalsis and TLOSR. Clip‐defined oesophageal segment length change was measured at 0.5‐s intervals. The magnitude of the most distal segment shortening was least with TLOSR, greatest with primary peristalsis and intermediate with secondary peristalsis. Conversely, maximal overall oesophageal shortening during TLOSR, evidenced by SCJ movement, was similar to that during primary peristalsis. In 3/12 TLOSRs, the moment of LOS opening and gas reflux was optimally imaged; SCJ excursion was 0.3 ± 0.1 cm prior to LOS opening and 1.4 ± 0.7 cm immediately after gas reflux. The segmental pattern of oesophageal shortening was distinct during primary peristalsis, secondary peristalsis and TLOSR. During TLOSR, significant elevation of the SCJ occurred only after LOS opening, suggesting that this was a consequence of oesophageal distension induced by gas reflux rather than a component of the opening mechanism.
HIV‐associated brain pathology: a comparative international study
Authors: Davies J. , Everall I. P. , Weich S. , Glass J. , Sharer L. R. , Cho E. S. , Bell J. E. , Majtenyi C. , Gray F. , Scaravilli F. , Lantos P. L. 
Published: March 2003

J. Davies, I. P. Everall, S. Weich, J. Glass, L. R. Sharer, E. S. Cho, J. E. Bell, C. Majtenyi, F. Gray, F. Scaravilli and P. L. Lantos (1998) Neuropathology and Applied Neurobiology24, 118–124HIV‐associated brain pathology: a comparative international studyLittle is known about the frequency and variation of HIV‐associated brain pathology in different geographical centres. To assess whether there is an association between the frequency of disease and demographic factors we examined the neuropathological findings in four European and two American cities. The cities included London, Edinburgh, Paris, Budapest, Baltimore and Newark. Information was collected on a total of 1144 cases. HIV encephalitis was the most common observation in all the centres, although its frequency varied between them (P < 0.01). Furthermore, there were significant differences (P < 0.001) between the various categories of exposure and the frequency of HIV encephalitis in Edinburgh and other centres. The occurrence of toxoplasmosis, progressive multifocal leukoencephalolpathy (PML) and cryptococcal infection also differed between the various centres (P < 0.01). None of the findings was attributable to age, sex, or ethnic origin, but the introduction of anti‐retroviral treatment, such as Zidovudine, may have been important. Overall, this study highlights geographical variability and the potential importance for group of exposure and anti‐retroviral medication as factors affecting the development of various HIV‐associated brain lesions.
The threat to primates and other mammals from the bushmeat trade in Africa, and how this threat could be diminished
Authors: Jones-Bowen Evan , Pendry Stephanie 
Published: March 2003

AbstractThe threat that the bushmeat trade presents to primates and other taxa was assessed from the literature, including data from markets, village hunting studies and logging concessions in Central and West Africa. In many cases the numbers of both common and protected species of primate being killed throughout the region are thought to be unsustainable. This is also the case for other taxa involved in the bushmeat trade, which crosses geographic, cultural and economic boundaries. A suite of measures must be considered to mitigate the effects of this trade, and these measures will have to recognize the local, regional and national socio-economic importance of the trade if they are to result in long-term conservation success.
Risk factors for low birthweight in north‐east Brazil: the role of caesarean section
Authors: Silva Antônio A.M. , Lamy‐Filho Fernando , Alves Maria T.S.S.B. , Coimbra Liberata C. , Bettiol Heloisa , Barbieri Marco A. 
Published: March 2003

SummaryCaesarean section (CS) delivery is associated with low birthweight (LBW) in south‐east Brazil. A hospital‐based study was conducted on singleton infants from mothers residing in São Luís, to assess if an association between CS and LBW was found in the northern part of the country, where the CS rate is lower than in the south‐east. A standardised questionnaire was administered to a sample of 2541 mothers in 10 hospitals, representing 94% of all deliveries, from March 1997 to February 1998. In a logistic model, type of delivery was the independent variable, the other variables were treated as confounders, and interaction terms were added between type of delivery and all other factors. LBW was associated with low maternal height, maternal smoking, primiparity, previous LBW, public insurance, preterm birth and CS. The CS rate was 33.7%. The risk of CS was higher for primiparous and married mothers, those with high level of schooling and attended by the same physician during prenatal and delivery care, deliveries held in private hospitals, daylight hours or evenings, and for those mothers who had adequate prenatal care. Because it appears unlikely that only medical reasons are operative, it is a possibility that CS could cause LBW, reflecting abusive indications for elective CS.
Prevalence of cigarette smoking in pregnant women participating in the special supplemental nutrition programme for Women, Infants and Children (WIC) in Minneapolis and Saint Paul, Minnesota, USA
Authors: Ross Julie A. , Swensen Andrine R. , Murphy Sharon E. 
Published: March 2003

SummarySeveral adverse birth outcomes are associated with cigarette smoking. It is important to determine the prevalence of cigarette smoking among pregnant low‐income women and to evaluate their smoking cessation patterns in order to target appropriate interventions. Ethnically diverse pregnant women aged 15–45 years were recruited from Minneapolis or Saint Paul Women, Infants, and Children (WIC) clinics before their third trimester. Serum cotinine levels were assayed for 98 women and compared with self‐report. The women were unaware that their smoking status would be validated. Twenty‐one (21%) women had a positive serum cotinine value (≥3 ng/mL); 16 (76%) admitted smoking within the previous 24 h before interview and five denied smoking. Of the five, four had cotinine levels that could suggest passive smoke exposure. Thirty‐seven women (38%) admitted cigarette smoking during the pregnancy but before knowing that they were pregnant; 18 (49%) of these denied current smoking at the interview and also presented with negative cotinine levels. These data suggest that some participants in WIC make a concerted effort to quit smoking when they find out they are pregnant, and are generally truthful when reporting their smoking habits during pregnancy.
Maternal second‐trimester serum ferritin concentrations and subsequent risk of preterm delivery
Authors: Xiao Rong , Sorensen Tanya K. , Frederick Ihunnaya O. , El‐Bastawissi Amira , King Irena B. , Leisenring Wendy M. , Williams Michelle A. 
Published: March 2003

SummaryWe studied the relationship between maternal second‐trimester serum ferritin concentrations and preterm delivery. The 312 preterm delivery cases, studied in aggregate and in subgroups [spontaneous preterm labour, preterm premature rupture of membranes, medically induced preterm delivery, moderate preterm delivery (gestational age at delivery 34–36 weeks) and very preterm delivery (gestational age at delivery <34 weeks)] were compared with 424 randomly selected women who delivered at term. Maternal ferritin concentrations, measured in serum collected at 17 weeks gestation on average, was determined using a two‐site chemiluminometric immunoassay. Using multiple logistic regression, we derived maximum likelihood estimates of adjusted odds ratios (OR) and 95% confidence intervals [CI]. Elevation in maternal second‐trimester ferritin was weakly associated with the risk of preterm delivery overall. After adjusting for possible confounding by maternal age, race/ethnicity, parity, Medicaid payment status and smoking during the index pregnancy, the OR for extreme quartiles (>64.5 vs. <26.0 ng/mL) of ferritin was 1.3 [95% CI 0.8, 2.1]. Stratified analyses indicated that elevated maternal serum ferritin was associated with an increased risk of preterm premature rupture of membranes (OR = 2.1; 95% CI 1.1, 4.1), but not with spontaneous preterm labour (OR = 0.9; 95% CI 0.4, 1.7) or medically induced preterm delivery (OR = 1.1; 95% CI 0.6, 2.0). The relationship between elevated maternal second‐trimester serum ferritin concentrations and preterm delivery was strongest for spontaneous very preterm deliveries (<34 weeks gestation). Women with ferritin concentrations in the highest decile (>96 ng/mL) experienced a 2.7‐fold increased risk of delivering before 34 completed weeks, compared with women with concentrations <26.0 ng/mL. These results are consistent with some previous reports, and further underline the potential for heterogeneity in the aetiology of preterm delivery.
The Schistosoma mansoni egg‐derived r38 peptide‐induced Th1 response affects the synchronous pulmonary but not the asynchronous hepatic granuloma growth
Authors: Chen Yiguang , Boros Dov L. 
Published: March 2003

SummaryThe p38 peptide derived from Schistosoma mansoni egg‐antigens (SEA) is a preferential inducer of the Th1 response. In the present study, we investigated whether induction of a p38‐specific Th1 or Th2 response can influence granuloma development in infected or sensitized mice. Mice sensitized with SEA/IL‐12 3 weeks after infection but before worm oviposition commenced developed Th1 cytokine responses and had significantly reduced hepatic granuloma size. Similar immunization with p38/IL‐12 induced a strong peptide‐specific Th1, mixed SEA‐specific Th1/Th2 responses without effect on hepatic granuloma development. Presentation of p38 with alum or alum/IL‐12 mixture enhanced Th2 cytokine responses and hepatic granuloma sizes. In the synchronized pulmonary model, sensitization of naïve mice with p38/IL‐12 induced a strong Th1 cytokine production to p38 and SEA, led to a moderate increase in granuloma growth at days 4 and 8 following egg injection and actually promoted the resolution of the lesion by day 16. Sensitization with p38 in alum induced Th2 cytokine production and generated the largest granulomas whereas the p38/alum/IL‐12 sensitized group showed intermediate results in cytokine production and granuloma growth. Thus, in infected mice, the p38 induced strong Th1 response was insufficient to cross‐regulate the evolving Th2 environment that generated large granulomas.
Relationship between reactive nitrogen intermediates and total immunoglobulin E, soluble CD21 and soluble CD23: comparison between cerebral malaria and nonsevere malaria
Authors: Nacher Mathieu , Singhasivanon Pratap , Kaewkungwal Jaranit , Silachamroon Udomsak , Treeprasertsuk Sombat , Tosukhowong Thanawat , Vannaphan Suparp , Looareesuwan Sornchai 
Published: March 2003

SummaryTo search for evidence of a protective role of the CD23/NO pathway against cerebral malaria, concentrations of reactive nitrogen intermediates (RNI) and sCD21, total immunoglobulin (Ig)E and sCD23 were compared between 17 cases of cerebral malaria and 33 controls. The geometric mean of sCD23 concentration was higher among cerebral malaria cases than among controls (optical density 2643/1495, P = 0·01). The ratio between sCD21 and sCD23 was significantly lower in cerebral malaria cases than in controls (0·67 ± 0·02 versus 0·77 ± 0·02, respectively, P = 0·009). Multiple linear regression analysis showed that, among cerebral malaria cases, there was a clear correlation between RNI and both IgE (P = 0·007) and sCD21 (P < 0·0001). Among controls, there was a strong negative correlation between RNI and sCD23 concentrations (r = −0·61, P < 0·0001). However, multivariate analysis unmasked the fact that, in controls, there was also a positive correlation between RNI and IgE (P = 0·045). Logistic regression showed that increased RNI concentrations were associated with a cerebral malaria adjusted odds ratio of 1·05 per unit increase [95% confidence interval (CI) 1·006–1·1, P = 0·02] and that an increased ratio between sCD21 and sCD23 was associated with protection from cerebral malaria (adjusted OR = 0·00001 per unit increase (95% CI 0–0·03, P = 0·005). These different immunological profiles suggest that, among controls, the CD23/NO pathway was chronically stimulated whereas, in cerebral malaria, its stimulation was acute, which could explain why some patients developed cerebral malaria and others did not.
Respiratory gas exchanges of termites from the Sabah (Borneo) assemblage
Authors: Jeeva D. , Bignell D. E. , Eggleton P. , Maryati M. 
Published: March 2003

Abstract.Oxygen uptake and carbon dioxide release at 28°C were determined in worker castes of twenty‐six species of forest termites from the Danum Valley Conservation Area, south‐east Sabah, by Warburg manometry.Metabolic rate varied inversely with body weight in a suite of soil‐, wood/soil‐ and wood‐feeding species, giving a slope (in a log–log plot) of – 0.63. However, a number of large species, actively foraging forms such as Macrotermes malaccensis, M. gilvus, Havilanditermes atripennis and Hospitalitermes hospitalis, but also the wood‐feeding Schedorhinotermes sarawakensis, showed an oxygen consumption greater than expected for their body weight. Rates of methane emission were above 0.100 μmol g–1 h–1 in seventeen species, with very high fluxes in two wood/soil‐feeders, Termes borneensis (0.546 ± 0.163 μmol g–1 h–1) and Prohamitermes mirabilis (0.303 ± 0.123 μmol g–1 h–1). Of the fifteen remaining species, seven were soil‐feeders, five were wood‐feeders, two were wood/litter‐feeders and a single species fed on lichen and moss. Low or negligible CH4 emissions (< 0.100 μmol g–1 h–1) were observed in three other species, all wood‐feeders.An apparent respiratory quotient (RQapp) was calculated using xCO2 and xO2 (corrected for methane emission, but not hydrogen). Mean RQapp was at or above 1.00 in eleven species and between 0.95 and 1.00 in a further six species, the two sets of species together representing all trophic groups, including lichen‐feeders. This is argued to be consistent with carbohydrate being the principal substrate supporting respiration.