bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection of ‘Candidatus Liberibacter asiaticus’ in Diaphorina citri and Its Importance in the Management of Citrus Huanglongbing in Florida
Authors: Manjunath K. L. , Halbert S. E. , Ramadugu C. , Webb S. , Lee R. F.
Published: March 2008

Citrus huanglongbing (HLB or citrus greening), is a highly destructive disease that has been spreading in both Florida and Brazil. Its psyllid vector, Diaphorina citri Kuwayama, has spread to Texas and Mexico, thus threatening the future of citrus production elsewhere in mainland North America. Even though sensitive diagnostic methods have been developed for detection of the causal organisms, Candidatus Liberibacter spp., the pathogen cannot be detected consistently in plants until symptoms develop, presumably because of low titer and uneven distribution of the causal bacteria in nonsymptomatic tissues. In the present study, TaqMan based real-time quantitative polymerase chain reaction methodology was developed for detection of ‘Ca. L. asiaticus’ in D. citri. Over 1,200 samples of psyllid adults and nymphs, collected from various locations in Florida, from visually healthy and HLB symptomatic trees at different times of the year were analyzed to monitor the incidence and spread of HLB. The results showed that spread of ‘Ca. L. asiaticus’ in an area may be detected one to several years before the development of HLB symptoms in plants. The study suggests that discount garden centers and retail nurseries may have played a significant role in the widespread distribution of psyllids and plants carrying HLB pathogens in Florida.
Genetic Differentiation of Magnaporthe oryzae Populations from Scouting Plots and Commercial Rice Fields in Korea
Authors: Park S.-Y. , Milgroom M. G. , Han S. S. , Kang S. , Lee Y.-H.
Published: March 2008

A previous study of the diversity and population structure of the rice blast fungus, Magnaporthe oryzae, over a 20-year period in Korea, found novel fingerprint haplotypes each year, and the authors hypothesized that populations might experience annual bottlenecks. Based on this model, we predicted that M. oryzae populations would have little or no genetic differentiation among geographic regions because rice blast is commonly found throughout Korea each year and M. oryzae would have to disperse from small populations surviving annually between rice crops. To test this hypothesis, we sampled M. oryzae from rice fields in eight provinces in Korea in a single year (1999). In four provinces, we sampled from a set of rice cultivars commonly grown in commercial fields (group I); because of low disease incidence in four other provinces, we could not sample from commercial fields and instead sampled from scouting plots of different cultivars set up for detecting new pathotypes of M. oryzae (group II). All isolates were genotyped with DNA fingerprint probes MGR586 and MAGGY, a telomere-linked gene family member TLH1, the PWL2 host specificity gene and mating type. Fingerprint haplotypes clustered into two distinct lineages corresponding to the two sets of cultivars (groups I and II), with haplotype similarities of 71% between lineages and >76% within lineages. Isolates from the same cultivar within group I were genetically differentiated among locations, and isolates within the same location were differentiated among cultivars. Differentiation for TLH1 and PWL2 was significant (P < 0.03), but not as strong as for fingerprint markers. Similar analyses were not possible among group II isolates because too few isolates were available from any one cultivar. All isolates were in the same mating type, Mat1-1, ruling out sexual reproduction as a source of novel haplotypes. When the 1999 samples were compared with the historical samples from the previous study, haplotypes of group I formed a separate cluster, while those of group II clustered with haplotypes from the historical sample. Altogether, geographic subdivision, monomorphism of mating type, and correlation of haplotypes to sets of cultivars are not consistent with the hypothesis of repeated turnover of haplotypes. Instead, the previous correlations of haplotypes to year might have been caused by inadequate sampling of haplotypes each year, highlighting the need for studies of population genetics to be conducted with systematic samples collected to address specific questions.
Selection for Quantitative Trait Loci Associated with Resistance to Stewart's Wilt in Sweet Corn
Authors: Pataky J. K. , Bohn M. O. , Lutz J. D. , Richter P. M.
Published: March 2008

The objectives of this research were to identify quantitative trait loci (QTL) for Stewart's wilt resistance from a mapping population derived from a sweet corn hybrid that is highly resistant to Pantoea stewartii and to determine if marker-based selection for those QTL could substantially improve Stewart's wilt resistance in a population derived from a cross of resistant lines and a highly susceptible sweet corn inbred. Three significant QTL for Stewart's wilt resistance on chromosomes 2 (bin 2.03), 5 (bin 5.03), and 6 (bin 6.06/6.07) explained 31% of the genetic variance in a population of 110 F3:4 families derived from the sweet corn hybrid Bonus. The three QTL appeared to be additive in their effects on Stewart's wilt ratings. Based on means of families that were either homozygous or heterozygous for marker alleles associated with the resistance QTL, the QTL on chromosomes 2 and 6 appeared to have dominant or partially dominant gene action, while the QTL on chromosome 5 appeared to be recessive. A population of 422 BC2S2 families was derived from crosses of a sweet corn inbred highly susceptible to Stewart's wilt, Green Giant Code 88 (GG88), and plants from two F3:4 families (12465 and 12467) from the Bonus mapping population that were homozygous for marker alleles associated with Stewart's wilt resistance at the three QTL. Mean Stewart's wilt ratings for BC2S2 families were significantly (P < 0.05) lower for families that were homozygous for the bnlg1902 marker allele (bin 5.03) from resistant lines 12465 or 12467 than for families that were heterozygous at this marker locus or homozygous for the bnlg1902 marker allele from GG88. Resistance associated with this QTL was expressed only if F3:5 or BC2S2 families were homozygous for marker alleles associated with the resistant inbred parent (P1). Marker alleles identified in the F3:5 mapping population that were in proximity to the resistance QTL on chromosomes 2 and 6 were not polymorphic in crosses of GG88 with 12465 and 12467. Selection for other polymorphic marker loci adjacent to these two regions did not improve Stewart's wilt resistance of BC2S2 families.
Dynamic social networks and the implications for the spread of infectious disease
Authors: Read Jonathan M , Eames Ken T.D , Edmunds W. John
Published: March 2008

Understanding the nature of human contact patterns is crucial for predicting the impact of future pandemics and devising effective control measures. However, few studies provide a quantitative description of the aspects of social interactions that are most relevant to disease transmission. Here, we present the results from a detailed diary-based survey of casual (conversational) and close contact (physical) encounters made by a small peer group of 49 adults who recorded 8661 encounters with 3528 different individuals over 14 non-consecutive days. We find that the stability of interactions depends on the intimacy of contact and social context. Casual contact encounters mostly occur in the workplace and are predominantly irregular, while close contact encounters mostly occur at home or in social situations and tend to be more stable. Simulated epidemics of casual contact transmission involve a large number of non-repeated encounters, and the social network is well captured by a random mixing model. However, the stability of the social network should be taken into account for close contact infections. Our findings have implications for the modelling of human epidemics and planning pandemic control policies based on social distancing methods.
Pushing versus pulling: division of labour between tarsal attachment pads in cockroaches
Authors: Clemente Christofer J , Federle Walter
Published: March 2008

Adhesive organs on the legs of arthropods and vertebrates are strongly direction dependent, making contact only when pulled towards the body but detaching when pushed away from it. Here we show that the two types of attachment pads found in cockroaches (Nauphoeta cinerea), tarsal euplantulae and pretarsal arolium, serve fundamentally different functions. Video recordings of vertical climbing revealed that euplantulae are almost exclusively engaged with the substrate when legs are pushing, whereas arolia make contact when pulling. Thus, upward-climbing cockroaches used front leg arolia and hind leg euplantulae, whereas hind leg arolia and front leg euplantulae were engaged during downward climbing. Single-leg friction force measurements showed that the arolium and euplantulae have an opposite direction dependence. Euplantulae achieved maximum friction when pushed distally, whereas arolium forces were maximal during proximal pulls. This direction dependence was not explained by the variation of shear stress but by different contact areas during pushing or pulling. The changes in contact area result from the arrangement of the flexible tarsal chain, tending to detach the arolium when pushing and to peel off euplantulae when in tension. Our results suggest that the euplantulae in cockroaches are notadhesiveorgans but ‘frictionpads’, mainly providing the necessary traction during locomotion.
Congestion, ramp metering and tolls
Authors: Varaiya Pravin
Published: March 2008

The cell transmission model of a freeway is used to compare four congestion-reducing schemes: (R) ramp control only; (T) one lane is tolled and ramps are uncontrolled; (B) bottlenecks are tolled and ramps are uncontrolled; and (RB) ramps are controlled and bottlenecks are tolled. In the base case, ramps are uncontrolled and there are no tolls. It is found that (T) is inefficient and may leave all travellers worse off; (R), (B) and (RB) can achieve efficient freeway use; (B) can eliminate queues, but has adverse spatial and equity side effects; (RB) minimizes these side effects. (RB) is likely to be least costly to implement and maintain.
Control of communication networks: welfare maximization and multipath transfers
Authors: Key Peter B , Massoulié Laurent
Published: March 2008

We discuss control strategies for communication networks such as the Internet. We advocate the goal of welfare maximization as a paradigm for network resource allocation. We explore the application of this paradigm to the case of parallel network paths. We show that welfare maximization requires active balancing across paths by data sources, and potentially requires implementation of novel transport protocols. However, the only requirement from the underlying ‘network layer’ is to expose the marginal congestion cost of network paths to the ‘transport layer’. We further illustrate the versatility of the corresponding layered architecture by describing transport protocols with the following properties: they achieve welfare maximization when each communication may use an arbitrary collection of paths; available in an overlay; and are combined in series and parallel. We conclude by commenting on incentives, pricing and open problems.
Development of COS genes as universally amplifiable markers for phylogenetic reconstructions of closely related plant species
Authors: Li Mingai , Wunder Jörg , Bissoli Gaetano , Scarponi Eliana , Gazzani Silvia , Barbaro Enrico , Saedler Heinz , Varotto Claudio
Published: March 2008

With the aim of developing widely applicable gene markers for phylogenetic reconstructions at low taxonomic level, we tested the low copy nuclear Conserved Ortholog Set (COS) genes. Most of the 15 genes tested provided good amplification efficiency (as compared with rbcL) from a set of 67 representative angiosperm families. Nine selected COS markers were further characterized at both intra‐ and interfamilial level on a test set, including 25 species representative of 15 different families. While four of the COS led to incongruent results, the remaining five improved the phylogenetic reconstructions of closely related species as illustrated in the case of Orobanchaceae species. They were found to be highly informative in phylogenetic reconstruction of congeneric species, where introns provide a higher proportion of parsimony informative sites in comparison with traditional phylogenetic markers such as ITS and matK. At higher phylogenetic distance, where only coding regions could be aligned, the polymorphism levels of the COS ranged between those of ndhF and matK.

On the basis of these results, the success rate in developing universally amplifiable low copy nuclear markers based on COS genes is about 30%. We report the successful development of five pCOS that, together with a few other well characterized genes, such as Rpb2 and GbssI, can be considered the closest approximation to low‐copy “universally” amplifiable markers for phylogeny in plants at present. The possible pitfalls of universally amplifiable COS marker development and their range of applicability at different taxonomic levels in comparison with traditional phylogenetic molecular markers are discussed.

© The Willi Hennig Society 2008.
Availability of lipid emulsion in obstetric anaesthesia in the UK: a national questionnaire survey
Authors: Williamson R. M. , Haines J.
Published: March 2008

There is evidence that administration of lipid emulsion improves outcome in cardiovascular collapse secondary to local anaesthetic toxicity. We sent a questionnaire to the lead consultant anaesthetist in every consultant‐led labour ward in the UK asking about local guidelines for treatment of cardiac arrest, and whether or nor lipid emulsion was available on the labour ward and included in the guideline. We received replies from 195 (86%) labour wards. One hundred and seven (55%) reported having a guideline for the treatment of cardiovascular collapse secondary to local anaesthetic toxicity. Of these guidelines, lipid emulsion was included in 78 (40%). Lipid emulsion was readily available on 95 labour wards (49%). Of the remaining units, there were plans to make lipid available in the near future in 46 (46%). Of the 95 labour wards where lipid emulsion was readily available, 80 (84%) had a recommended dose regimen for its administration. Around three‐quarters of labour wards in the UK either have lipid emulsion available or plan to obtain it. This uptake should ideally be 100%.
The rate of alveolar‐capillary uptake of sevoflurane and nitrous oxide following anaesthetic induction
Authors: Peyton P. J. , Fortuin M. , Robinson G J. B. , Stuart‐Andrews C. , Pierce R. , Thompson B. R.
Published: March 2008

The rate of anaesthetic gas uptake from the breathing system has been extensively measured, but this does not reflect the true rate of early gas uptake by pulmonary blood, which drives inhalational induction of anaesthesia. In eight patients undergoing coronary bypass surgery, we measured the rate of alveolar‐capillary uptake of anaesthetic gases up to 30 min following introduction of 0.5% sevoflurane and 33% nitrous oxide using the reverse Fick method, in which blood partial pressures were measured using a headspace equilibration technique. Simultaneous measurements of gas uptake from the breathing system were made by indirect calorimetry. Measured rates of sevoflurane and nitrous oxide uptake from the breathing system agreed well with previously described formulae when adjusted for inspired concentration. The time course of alveolar‐capillary gas uptake followed a characteristic rising curve peaking at 3–4 min and then exponentially declining, and for nitrous oxide was significantly higher than previously estimated.
Subarachnoid haematoma after spinal anaesthesia mimicking transient radicular irritation: a case report and review
Authors: Lam D. H.
Published: March 2008

I report a patient with a spinal subarachnoid haematoma after difficult spinal anaesthesia who presented with symptoms of radicular irritation, and who recovered with conservative management. Subarachnoid haematoma is rare after spinal anaesthesia; a literature review found nine cases. In the majority of these cases, spinal anaesthesia had been difficult and unsuccessful. Other risk factors included antiplatelet and anticoagulant therapy, and direct spinal cord trauma. All the previous cases required decompressive laminectomy.
In vitro evaluation of the CeVOXTM continuous central venous oxygenation monitoring system*
Authors: Baulig W. , Dullenkopf A. , Hasenclever P. , Schmid E. R. , Weiss M.
Published: March 2008

We investigated the in vitro performance of the CeVOXTM system for continuous monitoring of central venous oxygen saturation by spectrophotometry (Pulsion Medical Systems, Munich, Germany). Oxygen inflow into the system was varied, and oxygen saturation values measured by CeVOX were documented. Blood samples were simultaneously taken to assess oxygen saturation by co‐oximetry, and values were compared by Bland–Altman analysis. Sixty‐six data pairs were obtained at CeVOX and co‐oximetry values of 16–99% and 5.5–100%, respectively. Overall, CeVOX values only slightly overestimated co‐oximetry values (mean bias + 2.4%), but limits of agreement (2 SD of bias) were wide (− 11.8 to + 16.6%). Saturation measured by CeVOX underestimated that measured by co‐oximetry at higher oxygen concentrations and overestimated it at lower oxygen concentrations. There was a nearly linear correlation of the mean bias, suggesting a systematic error. We conclude that the current version of the CeVOX system does not reliably reflect oxygen saturation.
Retention of drug administration skills after intensive teaching
Authors: Wheeler D. W. , Degnan B. A. , Murray L. J. , Dunling C. P. , Whittlestone K. D. , Wood D. F. , Smith H. L. , Gupta A. K.
Published: March 2008

We have identified deficiencies in medical students' drug administration skills, and we attempted to address them with interactive online teaching modules and simulated critical incident scenarios. Short‐term improvements have been evident with this intensive effort, but medium‐term retention of skills has not been measured. A drug administration lecture, an online module and a simulated emergency scenario were offered to final year clinical students. None of the teaching was compulsory but participation was recorded, along with students' simulator performances and marks in an objective structured practical examination 9 months later. A poor simulator score predicted a poor performance in the later examination. Participation in the simulated scenario only significantly improved examination scores when supplemented by online teaching (p = 0.002). Intensive drug administration teaching using an online module and high fidelity simulation improves drug administration skills in the medium term. Students found simulation much more engaging than online teaching.
Peri‐operative anaesthetic management of cytoreductive surgery with hyperthermic intraperitoneal chemotherapy
Authors: Schmidt C. , Creutzenberg M. , Piso P. , Hobbhahn J. , Bucher M.
Published: March 2008

Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (HIPEC) is a long and complex procedure with significant blood and fluid loss during debulking and important pathophysiological alterations during the HIPEC phase. We performed a retrospective analysis of 78 consecutive patients undergoing cytoreductive surgery with HIPEC at a university hospital. Our data demonstrate large intra‐operative fluid turnover, with 51% of patients requiring a blood transfusion. During HIPEC, airway pressure and central venous pressure increased with a lower oxygenation ratio as a result of increased intra‐abdominal pressure with the closed abdomen technique. As a consequence of the raised body temperature, heart rate, end tidal carbon dioxide and arterial lactate levels increased with a slight metabolic acidosis. Peri‐operative analysis of routine clotting parameters revealed disturbances of the coagulation status. For pain management, 72% of patients received supplementary thoracic epidural analgesia with consequential peri‐operative opioid sparing and a reduced duration of postoperative ventilation.
Traumatic haemorrhage into an occult phaeochromocytoma: presentation and management in a patient with septic shock
Authors: Saxena N. , Parry‐Jones A. J. D.
Published: March 2008

Phaeochromocytomas can have a variety of presentations; however, traumatic haemorrhage into a phaeochromocytoma is a rare presentation. Diagnosing and managing a critically ill, septic patient with a phaeochromocytoma can be very challenging. We report a case of a 57‐year‐old man, with a previously undiagnosed phaeochromocytoma, who presented initially with bowel perforation following an assault. Following a laparotomy for bowel resection and anastomosis, whilst on the intensive care unit, he developed paroxysmal severe hypertension overlying septic shock. Phaeochromocytoma was confirmed using a computed tomography scan and urinary assay of metanephrines and catecholamines. We managed the haemodynamic instability using labetalol and noradrenaline infusions. As his septic state improved he was started on conventional therapy and following control of his symptoms over the next few weeks, he underwent an uncomplicated right sided adrenalectomy. He made a full recovery.
Safety in anaesthesia: a study of 12 606 reported incidents from the UK National Reporting and Learning System
Authors: Catchpole K. , Bell M. D. D. , Johnson S.
Published: March 2008

The incident reporting database at the National Patient Safety Agency was interrogated on the nature, frequency and severity of incidents related to anaesthesia. Of 12 606 reports over a 2‐year period, 2842 (22.5%) resulted in little harm or a moderate degree of harm, and 269 (2.1%) resulted in severe harm or death, with procedure or treatment problems generating the highest risk. One thousand and thirty‐five incidents (8%) related to pre‐operative assessment, with harm occurring in 275 (26.6%), and 552 (4.4%) related to epidural anaesthesia, with harm reported in 198 (35.9%). Fifty‐eight occurrences of anaesthetic awareness were also examined. This preliminary analysis is not authoritative enough to warrant widespread changes of practice, but justifies future collaborative approaches to reduce the potential for harm and improve the submission, collection and analysis of incident reports. Practitioners, departments and professional bodies should consider how the information can be used to promote patient safety and their own defensibility.
Laryngoscopy force in the sniffing position compared to the extension‐extension position
Authors: Lee L. , Weightman W. M.
Published: March 2008

Laryngoscopy is sometimes easier with the patient’s head and neck in the extension‐extension position (head extension with the neck extended by the head section of the table bent down at 30°) rather than the classical ‘sniffing the morning air’ position. We therefore tested the hypothesis that the axial force required for laryngoscopy is less in the extension‐extension than the sniffing position. We measured the force axial to the handle of a Macintosh 3 laryngoscope in 20 subjects under general anaesthesia who had been given neuromuscular blocking drugs. Measurement of force was made in the sniffing position and the extension‐extension position. The mean (SD) axial force required in the extension‐extension position was lower than in the sniffing position (19.6 (7.8) N versus 23.6 (8.6) N, p = 0.04). In the setting of routine tracheal intubation, less force is required when the patient is in the extension‐extension position than in the sniffing position.
A population pharmacokinetic meta‐analysis of maraviroc in healthy volunteers and asymptomatic HIV‐infected subjects
Authors: Chan Phylinda L. S. , Weatherley Barry , McFadyen Lynn
Published: March 2008

AIMS

To develop a population pharmacokinetic model for maraviroc, a noncompetitive CCR5 antagonist, after oral administration of tablets to healthy volunteers and asymptomatic HIV‐infected subjects and to quantify the inherent variability and influence of covariates on the parameters of the model.

METHODS

Rich pharmacokinetic data available from 15 studies in healthy volunteers (n = 365) and two studies in asymptomatic HIV‐infected subjects (n = 48) were analysed using NONMEM. Maraviroc was administered as single or multiple oral tablet doses under fasted and fed conditions. Doses ranged from 100 to 1800 mg day−1.

RESULTS

A two‐compartment model parameterized to separate out absorption and clearance components on bioavailability was used. Absorption was described by a lagged first‐order process. A sigmoid Emax model described the effect of dose on absorption. A visual predictive check and nonparametric bootstrap evaluation confirmed that the model was a good description of the data. Typical CL, Vc and Vp values for a 30‐year‐old non‐Asian are 51.5 l h−1, 132 l and 277 l, respectively.

CONCLUSIONS

For the typical non‐Asian subject, fasted bioavailability increased asymptotically with dose from 24% at 100 mg to 33% at 600 mg. A high‐fat meal taken with maraviroc reduced exposure by 43% for a 100‐mg dose to approximately 25% at doses of 600 mg. The typical Asian subject had a 26.5% higher AUC than the typical non‐Asian subject irrespective of dose, a difference not considered to be clinically relevant. None of the other covariates tested had any clinically relevant effects on exposure.
p21Cip1 expression is increased in ambient oxygen, compared to estimated physiological (5%) levels in rat muscle precursor cell culture
Authors: Lees S. J. , Childs T. E. , Booth F. W.
Published: March 2008

Abstract.  Objective: While it is common practice to culture cells in the presence of ambient oxygen (~21% O2), O2 level observed in the physiological environment is often much lower. Previous efforts to culture a variety of different stem cells, including muscle precursor cells (MPC), under O2 conditions that better mimic in vivo conditions have resulted in enhanced proliferation. In the present study, we hypothesized that 20% O2 in culture represents a sufficient stimulus to cause increased expression of two key negative regulators of the cell‐cycle Cip/Kip family of cyclin‐dependent kinase inhibitors, p21Cip1 and p27Kip1, in MPCs. Materials and methods: MPCs were isolated from Fischer 344 × Brown Norway F1 hybrid male rats and O2 was adjusted in culture using a tri‐gas incubator. Results: 5‐Bromo‐2′‐deoxyuridine incorporation, cell number and nuclear proliferating cell nuclear antigen expression were all decreased after 48 h culture in 20% O2, compared to 5% O2. Twenty per cent O2 had no effect on either p27Kip1 promoter activity or protein expression. Although p21Cip1 promoter activity remained unchanged between 5% and 20% O2, there were significant increases in both p21Cip1 mRNA and protein expression. Furthermore, 20% O2 caused an increase in p21Cip1 mRNA stability and p53 transcription factor activity. Conclusion: These findings are considered important because they reveal p21Cip1 as a critical regulatory protein that needs to be considered when interpreting proliferation data from MPCs studied in culture. In addition, O2‐dependent regulation of MPC proliferation is relevant to conditions, including sarcopenia, heart failure, cancer and muscular dystrophy, where increased oxidative stress exists.
Human plasma accelerates immortalization of B lymphocytes by Epstein–Barr virus
Authors: Manor E.
Published: March 2008

Abstract.  Objective: Serum and plasma contain species‐specific factors that modulate cell population growth and function, and that are required for proliferation of most cell cultures. Foetal calf serum (FCS) is the most common source of these growth factors. We studied the effect of human plasma (HP) on the immortalization process of B lymphocytes by Epstein–Barr virus (EBV) was studied. Materials and methods: The effect of HP as compared to FCS was done through assessment of cell proliferation. Results: It was found that HP (autologous and non‐autologous plasma) is more effective than FCS in generating lymphoblastoid cell lines, regardless of EBV status of the donors: 65% of HP‐supplemented cultures developed into lymphoblastoid cell lines by 7–14 culture days, as compared to 16% of cultures with FCS. In addition, 6% of HP‐supplemented cultures did not achieve becoming lymphoblastoid cell lines by day 35 in comparison to 94% of cultures with FCS. The higher proliferative effect of HP was not altered by heat inactivation or filtration. HP maintained its proliferative activity at 4 °C over 8 months, thus indicating that HP contains a stable growth factor(s), which accelerates B‐lymphocyte immortalization. Conclusion: The results support other studies that recommend the use of autologous plasma for tissue culture, mainly in the case of autologous transplantation. Furthermore, the use of HP allows preparation of lymphoblastoid cell lines from a small amount of peripheral blood in a shorter period of time and with a higher rate of success.
Are progenitor cells pre‐programmed for sequential cell cycles not requiring cyclins D and E and activation of Cdk2?
Authors: Xie D.‐X. , Yao J. , Zhang P. , Li X.‐L. , Feng Y.‐D. , Wu J.‐H. , Tao D.‐D. , Hu J.‐B. , Gong J.‐P.
Published: March 2008

Abstract.  Objectives: Based on studies of unicellular organisms or cultured mammalian cells, the generally accepted model of cell‐cycle regulation has been developed in which sequential (scheduled) expression of cyclins D, E, A and B and activation of Cdk2 and Cdk1 takes place. It is assumed that the same model is applicable both in vivo and in vitro. Materials and methods: In the present study, we compared proliferating marrow cells freshly isolated from healthy individuals with proliferating lymphocytes in cultures. Results: We demonstrate that during progression of freshly collected human bone marrow cells through G1, S and G2/M, only Cdk1 combined with cyclins A and B1 was distinctly present and active, and its activity gradually increased. In contrast, in vitro growing mitogen‐stimulated lymphocytes had perfectly scheduled sequential expression of all four cyclins and Cdk1 and Cdk2 activities. Conclusion: Our findings demonstrate that the pattern of cyclin expression and Cdk activity in bone marrow in vivo is distinctly different from the one observed for normal cells in vitro. Because proliferating bone marrow cells are predominantly expanding populations of committed progenitors, it is likely that during the expansion phase their cell‐cycle progression is pre‐programmed, being driven solely by Cdk1 combined either with cyclin A or with cyclin B1. Expansion of progenitor cells thus may not require the early steps of cell‐cycle regulation, associated with triggering progression by availability of growth factors and mitogens.
Influence of supramammary lymph node extract on in vitro cell proliferation
Authors: Duffy D. M. , Garrett S. M. , Ellis S. E. , Scott T. R.
Published: March 2008

Abstract.  Objectives: Experiments were conducted to evaluate whether or not bovine supramammary lymph node extract (LNE) could support cell proliferation when it was substituted for bovine growth serum (BGS) in cell culture media. Materials and Methods: Two different preparations of LNE were tested. The first yielded protein concentration of 3 mg/mL and the second contained 27 mg/mL protein. Three cell lines (MDA‐MB‐435, MAC‐T and 1C6) were used in serum starvation assays to evaluate LNE. Cell proliferation assays were used to determine growth stimulation in the presence of LNE, and short‐term or rapid adaptation cultures were evaluated for LNE effects on cell survival. Results: Heat‐inactivated preparation 1 supported cell proliferation as well as or better (12–39%) than BGS following 2 days of serum starvation in culture. The second lymph node preparation provided a stimulatory effect (263–702% greater than BGS across all cell lines) following serum starvation at 2.7 and 5.4 mg/mL protein supplementation. A gradual adaptation process with lymph node supplementation into media maintained cell population growth on a short‐term basis. However, once cells were trypsinized or scraped and re‐seeded into 2.7 mg/mL LNE protein containing media, cells were unable to re‐adhere, leaving them detached, and eventually appearing to be dead. Conclusions: Substitution of BGS with LNE protein dramatically stimulated cells to proliferate, but did not allow for rapid cell population growth adaptation in vitro.
Establishment of a gastric epithelial progenitor cell line from a transgenic mouse expressing the simian virus 40 large T antigen gene in the parietal cell lineage
Authors: Farook V. S. , Alkhalaf M. , Karam S. M.
Published: March 2008

Abstract.  Objective: In this study the gastric mucosa of transgenic mice expressing the simian virus 40 large T antigen gene in the parietal cell lineage is used to establish and characterize a new epithelial progenitor cell line. In these mice, proliferation and amplification of preparietal cells preclude their maturation into acid‐secreting parietal cells leading to achlorohydria, hyperplasia, dysplasia and eventually gastric adenocarcinoma.Materials and methods: Enzymatically dispersed gastric epithelial cells were cultured, cloned and screened using immunohistochemical methods, for expression of a variety of biomarkers of differentiated pit, parietal, enteroendocrine and neck/zymogenic cells.Results: A biomarker‐deficient cell line whose ultrastructural features resembled those of mouse gastric epithelial progenitor cells was established. Treatment with either hydrocortisone or oestrogen significantly enhanced proliferation of these cells, whereas retinoic acid inhibited their growth. No change in differentiation was detected with any of these treatments; however, when these cells were injected subcutaneously into nude mice, they proliferated to form tumours and undergo partial differentiation towards parietal cell lineage.Conclusion: This mouse gastric epithelial progenitor cell line could be useful as anin vitromodel to study growth properties, proliferation and differentiation of a subpopulation of gastric epithelial progenitor cells and also to study gastric carcinogenesis.
Conjugated linoleic acids differentially alter polyp number and diameter in the Apcmin/+ mouse model of intestinal cancer
Authors: Mandir N. , Goodlad R. A.
Published: March 2008

Abstract.  Objective: Dietary conjugated linoleic acids (CLA) have had many health benefits claimed for them, including antineoplastic actions. Materials and methods: The effects of the predominant forms of CLA, namely the c9t11 and t10c12 isomers, or a mixture of these on polyp development, were investigated in the ApcMin/+ mouse. CLAs have also been linked to altered rates of cell renewal and cell proliferation so this was also studied, as was a further means of increasing tissue mass, namely crypt fission. Results: The stomach and small intestine were significantly heavier in the t10c12, and in the mixture‐treated groups (P < 0.001). Crypt fission was increased in the middle small intestine by the t10c12 diet while colonic weight was reduced by c9t11 provision and crypts were 20% shorter. The t10c12 and the mixture significantly reduced polyp number in the proximal small intestine but they increased polyp diameter in the middle and distal small intestine, to an extent that the polyp burden was significantly increased at these sites. All CLAs significantly reduced polyp number in the colon, but the mixture significantly increased polyp diameter in the colon. Conclusion: Increased polyp diameter associated with t10c12 diet and especially with the mixture is a cause of concern, as this is the commercially available form. The naturally occurring isomer, c9t11 decreased colonic polyp number and did not increase diameter, suggesting that this natural isomer is the most likely to be protective.
Long‐term prognosis of medullary thyroid carcinoma
Authors: Rendl G. , Manzl M. , Hitzl W. , Sungler P. , Pirich C.
Published: March 2008

Objective  The clinical course of patients with medullary thyroid carcinoma (MTC) is variable, even in the subgroup of patients after surgery with curative intent and postoperatively persistent elevated calcitonin levels. This study aimed to evaluate the long‐term prognosis of survival in patients with MTC.

Patients  Long‐term survival was analysed in 32 patients with MTC being treated in an endocrine centre over a 40‐year period. Patients were classified as having sporadic MTC, familial MTC (FMTC), multiple endocrine neoplasia (MEN) IIA or MEN IIB.

Results  Seventeen patients had sporadic MTC (53·1%), eight had MEN IIA (25%) and three had MEN IIB (9·4%); the remaining four patients (12·5%) had not undergone genetic analysis until now. The overall average age at diagnosis was 42·0 years, and the median follow‐up time was 9·5 years (range 0·5–39 years). Mortality due to progressive MTC was 15·6%. The 5‐year survival rate was 96% (95% CI 89–100), the 10‐year survival rate 91% (95% CI 79–100), and the 15‐year survival rate 85% (95% CI 78–100). The estimated mean survival time after initial diagnosis was 31 years (95% CI 26·7–37·0). There is a significant difference in survival time between patients achieving complete remission compared with patients with biochemical persistent disease (P = 0·038) or metastasis (P = 0·0003). In five patients, advanced imaging with positron emission tomography/computed tomography (PET/CT) identified additional sites of tumour load. Eight more lymph node metastases were found in four patients and one local tumour recurrence in one patient by PET/CT.

Conclusion  The overall prognosis of MTC is favourable, even if the rate of biochemical cure is lower in MTC than in differentiated types of thyroid cancer. This is also true for patients with biochemically persistent disease. Whether the identification of further tumour sites by advanced imaging procedures such as PET/CT translates into a better prognosis in patients with persistently elevated calcitonin levels remains to be investigated.
Restoration options for potential persistence of submersed aquatic vegetation: combining ecological, hydrodynamic and sediment transport modelling
Authors: BEST ELLY P. H. , TEETER ALLEN M. , LANDWEHR KEVIN J. , JAMES WILLIAM F. , NAIR SHYAM K.
Published: March 2008

1. Restoration of shallow turbid lakes to promote growth of submersed aquatic vegetation (SAV) requires knowledge of the environmental factors affecting SAV growth and persistence, and a means to predict the success of SAV reestablishment under different management scenarios to improve these environmental conditions. We used a dynamic ecological modelling approach relating SAV responses to changes in physical and chemical conditions, with information on water level, flow and transparency being provided by hydrodynamic and sediment transport models.

2. The potential persistence of Vallisneria americana was similar under simulated environmental conditions in 1946 and in 1954, as was the potential persistence of Potamogeton pectinatus, indicating that the disappearance of V. americana from Peoria Lake (U.S.A.) previously attributed to an extended spring flood in 1954, may have been related to the combined effects of changes in water level, flow and water transparency as well as possibly other factors.

3. Recent environmental conditions (for 2000) proved not to be conducive for the colonization and persistence potential of V. americana, but would allow colonization by P. pectinatus. The construction of a hypothetical levee along the eastern descending line of the navigation channel in Upper Peoria Lake, which was expected to reduce fetch‐ and navigation‐related turbidity, did not improve the situation for V. americana and overall deteriorated the situation for P. pectinatus. Thus, such a hydraulic alteration, generally considered as beneficial for SAV restoration, may not always be successful.

4. The results of the simulations indicated that the environmental conditions for potential persistence in Peoria Lake were generally less favourable for V. americana than for P. pectinatus. Measures suggested to restore SAV communities in such a lake should aim at reducing concentrations of total suspended solids at the point of inflow by a factor of three to four and limiting fetch‐ and navigation‐related resuspension.
Effects of agriculture on wood breakdown and microbial biofilm respiration in southern Appalachian streams
Authors: MCTAMMANY M. E. , BENFIELD E. F. , WEBSTER J. R.
Published: March 2008

1. Agriculture causes high sediment, nutrient and light input to streams, which may affect rates of ecosystem processes, such as organic matter decay. In the southern Appalachians, socioeconomic trends over the past 50 years have caused widespread abandonment of farmland with subsequent reforestation. Physical and chemical properties of streams in these reforested areas may be returning to pre‐agriculture levels thereby creating the potential for recovery of ecosystem processes.

2. We examined wood breakdown and microbial activity on wood substrata in streams with different historical and current agricultural activity in their catchments. We analysed historical (1950) and recent (1998) forested land cover from large areas of the southern Appalachians and categorized streams based on percent forested land cover in these two time periods. Categories included a gradient of current agriculture from forested to heavily agricultural and reforestation from agriculture due to land abandonment. We compared microbial respiration on wood veneer substrata and breakdown of wood veneers among these land‐use categories. We also compared temperature, sediment accumulation and nitrogen and phosphorus concentrations.

3. Streams with current agriculture had higher concentrations of dissolved inorganic nitrogen than forested streams. Despite reforestation from agriculture, nitrogen concentrations were also elevated in streams with agricultural histories relative to forested streams. Temperature was also higher in agricultural streams but appeared to recover from historical agriculture through reforestation and stream shading.

4. Wood breakdown rates ranged from 0.0015 to 0.0076 day−1 and were similar to other studies using wood veneers to determine breakdown rate. Microbial respiration increased with incubation time in streams up to approximately 150 days, after which it remained constant. Neither wood breakdown nor microbial respiration was significantly different among land‐use categories, despite the observed physical and chemical differences in streams based on land‐use. Wood breakdown rates could be predicted by microbial respiration indicating microbial control of wood breakdown in these streams. Both breakdown and microbial respiration were negatively correlated with the amount of inorganic sediment accumulated on wood veneers.

5. Higher nutrients and temperature led us to expect faster breakdown and higher microbial respiration in agricultural streams, but sediment in these streams may be limiting microbial activity and breakdown of organic material resulting in little net effect of agriculture on wood breakdown. Wood may not be desirable as a tool for functional assessment of stream integrity due to its unpredictable response to agriculture.
Multi‐scale assessment of macroinvertebrate richness and composition in Mediterranean‐climate rivers
Authors: BONADA NÚRIA , RIERADEVALL MARIA , DALLAS HELEN , DAVIS JENNY , DAY JENNY , FIGUEROA RICARDO , RESH VINCENT H. , PRAT NARCÍS
Published: March 2008

1. Similar constraints in distant, but climatically comparable, regions may be expected to yield biotic assemblages with similar attributes. Environmental factors that constrain communities at smaller scales, however, may be different between climatically similar regions. Thus, patterns observed at large scales may differ from those detected at small scales, and international comparisons should be focussed at multiple scales.

2. Mediterranean‐climate regions (MCRs) are characterized by remarkable seasonal variability in precipitation and temperature. Accordingly, rivers in these regions have seasonal and predictable floods and droughts, and temporary reaches are frequent. Present in six geographical regions of the world, MCRs have similar environmental constraints and are ideal for testing intercontinental similarities between macroinvertebrate communities.

3. We examined aquatic macroinvertebrate taxon richness and composition in MCRs at three scales: regional, reach and macrohabitat. At the regional scale, the Mediterranean Basin had the highest taxon richness at family level, and southwestern Australia the lowest. Taxonomic composition showed c. 85% similarity between the northern hemisphere MCRs of California and the Mediterranean Basin, which were followed in similarity by South Africa. The two Australian MCRs (South west and South) showed a similarity to each other of about 70% whereas the Chilean fauna was the most distinct.

4. At the reach scale, taxon richness was not significantly different between permanent and temporary reaches in any MCR, whereas taxonomic composition was significantly different among northern hemisphere MCRs. At the macrohabitat scale, taxon richness was not significantly different between lotic and lentic macrohabitats within any of the MCRs, but differences in macroinvertebrate communities were found between macrohabitats when considering regions.

5. Our results show that the strength of similarity between distant but climatically similar regions is scale‐dependent, being highest at the macrohabitat scale. Although the similarities in richness and composition at the macrohabitat scale are presumed to be universal, the seasonal predictability of drought in MCRs is expected to result in characteristic macroinvertebrate responses at the reach scale. We suggest, however, that regional evolutionary history and environmental characteristics may override this general pattern of a similar response of MCRs at different scales. The Mediterranean Basin and California, having similar historical and environmental condition, thus appeared as the most similar MCRs at all scales.
Climate change affects colonization dynamics in a metacommunity of three Daphnia species
Authors: ALTERMATT FLORIAN , PAJUNEN V. ILMARI , EBERT DIETER
Published: March 2008

Climate change is expected to alter the range and abundance of many species by influencing habitat qualities. For species living in fragmented populations, not only the quality of the present patches but also access to new habitat patches may be affected. Here, we show that colonization in a metacommunity can be directly influenced by weather changes, and that these observed weather changes are consistent with global climate change models. Using a long‐term dataset from a rock pool metacommunity of the three species Daphnia magna, Daphnia longispina and Daphnia pulex with 507 monitored habitat patches, we correlated a four‐fold increase in colonization rate with warmer, drier weather for the period from 1982 to 2006. The higher colonization rate after warm and dry summers led to an increase in metacommunity dynamics over time. A mechanistic explanation for the increased colonization rate is that the resting stages have a higher exposure to animal and wind dispersal in desiccated rock pools. Although colonization rates reacted in the same direction in all three species, there were significant species‐specific effects that resulted in an overall change in the metacommunity composition. Increased local instability and colonization dynamics may even lead to higher global stability of the metacommunity. Thus, whereas climate change has been reported to cause a unidirectional change in species range for many other species, it changes the dynamics and composition of an entire community in this metacommunity, with winners and losers difficult to predict.