bluuebunny/crossref_metadata_2025 huggingface dataset:
Much Improved Water Use Efficiency of Rice under Non‐Flooded Mulching Cultivation
Authors: Xu Guo‐Wei , Zhang Zi‐Chang , Zhang Jian‐Hua , Yang Jian‐Chang
Published: October 2007

Water shortage is increasingly limiting the luxury use of water in rice cultivation. In this study, non‐flooded mulching cultivation of rice only consumed a fraction of the water that was needed for traditional flooded cultivation and largely maintained the grain yield. We also investigated the growth and development of rice plants and examined grain yield formation when rice was subjected to non‐flooded mulching cultivation. One indica hybrid rice combination was grown in a field experiment and three cultivation methods, traditional flooding (TF), non‐flooded straw mulching cultivation (SM) and non‐flooded plastic mulching cultivation (PM), were conducted during the whole season. Grain yield showed that there was no significant difference between SM and TF rice, but the grain yield of SM cultivation was significantly higher than that of PM. The tiller numbers were inhibited in the early stage under non‐flooded mulching cultivation, but the situation was reversed at the later period. Both SM and PM rice reduced dry matter accumulation of shoot, but increased root dry weight, enhanced the remobilization of assimilates from stems to grains and increased the harvest index. During the middle and later grain filling period, mulched plants showed a faster decrease in chlorophyll concentrations, photosynthetic rates of flag leaves and root activity than TF rice, indicating that non‐flooded mulching cultivation enhanced plant senescence. In comparison, SM treatment produced higher grain yield and, more dry matter accumulation and panicle numbers than the PM treatment. The overall results suggest that high yield of non‐flooded mulching cultivation of rice can be achieved with much improved irrigational water use efficiency.
Photosynthesis and Water Use Efficiency of Platycladus Orientalis and Robinia Pseudoacacia Saplings under Steady Soil Water Stress during Different Stages of Their Annual Growth Period
Authors: Wang Ming‐Chun , Wang Jin‐Xin , Shi Qing‐Hua , Zhang Jin‐Song
Published: October 2007

A simulated drought experiment was conducted in a rain‐free shed to test the physiological response of Platycladus orientalis and Robinia pseudoacacia saplings to steady soil water stress during different stages. The five soil water treatments were: 100%, 87.84%, 70%, 52.16% and 40% of field capacity. The results showed that the net photosynthetic rate of R. pseudoacacia decreased as soil water potential decreased in the range between −0.041 MPa and –0.292 MPa. The threshold value at which the net photosynthetic rate changed significantly was −0.12 MPa. The relationship between net photosynthetic rate of P. orientalis and soil water potential could be described as a quadratic parabola in the range between −0.041 MPa and −0.648 MPa. Analysis of variance showed significant differences in the net photosynthetic rate of P. orientalis between soil water potentials of −0.061 MPa ∼−0.648 MPa. Average water use efficiency (WUE) increased as soil water potential decreased, but the influence mechanism of soil water stress on leaf WUE and photosynthetic rate for the two species were different evidently.
In vivo biosensors
Authors: Wilson George S. , Ammam Malika
Published: October 2007

Detailed understanding of the dynamics of living systems requires a means to monitor, in real time, changes in the levels of key components in response to specific stimuli. Applications involving cultured cells, tissue slices and implantation in living systems are discussed.
Lysophosphatidic acid inhibits ghrelin secretion in the human gastric adenocarcinoma AGS cell line − role of mitogenic activated protein kinase signaling pathway
Authors: Pazos Yolanda , Alvarez Carlos J. P. , Camiña Jesus P. , Casanueva Felipe F.
Published: October 2007

Ghrelin, the endogenous ligand for the growth hormone secretagogue receptor type 1a (GHS‐R1a), is a 28 amino acid residue with a post‐translational octanoyl modification on Ser3. Despite the biomedical interest in this hormone, the fine details of its regulation and the mechanisms controlling its secretion are largely unknown. The present study analyzes the molecular steps involved in the full lysophosphatidic acid (LPA) receptor‐mediated activation of the mitogenic extracellular signal‐regulated kinase (ERK) pathway and its consequent role as an inhibitor of ghrelin secretion in the gastric adenocarcinoma cell line AGS. ERK1/2 phosphorylation mediated by LPA proceeds via activation of the type 2 LPA receptor, activation of the nonreceptor tyrosine kinase c‐Src, and subsequent transactivation of the epidermal growth factor receptor. Furthermore, LPA‐induced ERK activation was found to be independent of matrix metalloproteinases; thus, c‐Src acted as the scaffold‐transactivating epidermal growth factor receptor. Finally, a correlation was observed between the mitogenic effects of LPA and ghrelin secretion in the human gastric adenocarcinoma cell line AGS. These data suggest a possible physiological role of LPA in ghrelin secretion. The relationship found between LPA and ghrelin secretion might explain the low circulating levels of ghrelin observed in obese patients, as a bona fide reflex of the energetic stores.
Transcription of mammalian cytochrome c oxidase subunit IV‐2 is controlled by a novel conserved oxygen responsive element
Authors: Hüttemann Maik , Lee Icksoo , Liu Jenney , Grossman Lawrence I.
Published: October 2007

Subunit 4 of cytochrome c oxidase (CcO) is a nuclear‐encoded regulatory subunit of the terminal complex of the mitochondrial electron transport chain. We have recently discovered an isoform of CcO 4 (CcO4‐2) which is specific to lung and trachea, and is induced after birth. The role of CcO as the major cellular oxygen consumer, and the lung‐specific expression of CcO4‐2, led us to investigate CcO4‐2 gene regulation. We cloned the CcO4‐2 promoter regions of cow, rat and mouse and compared them with the human promoter. Promoter activity is localized within a 118‐bp proximal region of the human promoter and is stimulated by hypoxia, reaching a maximum (threefold) under 4% oxygen compared with normoxia. CcO4‐2 oxygen responsiveness was assigned by mutagenesis to a novel promoter element (5′‐GGACGTTCCCACG‐3′) that lies within a 24‐bp region that is 79% conserved in all four species. This element is able to bind protein, and competition experiments revealed that, within the element, the four core bases 5′‐TCNCA‐3′ are obligatory for transcription factor binding. CcO isolated from lung showed a 2.5‐fold increased maximal turnover compared with liver CcO. We propose that CcO4‐2 expression in highly oxygenated lung and trachea protects these tissues from oxidative damage by accelerating the last step in the electron transport chain, leading to a decrease in available electrons for free radical formation.
Substrate specificity of the pseudouridine synthase RluD in Escherichia coli
Authors: Leppik Margus , Peil Lauri , Kipper Kalle , Liiv Aivar , Remme Jaanus
Published: October 2007

Pseudouridine synthase RluD converts uridines at positions 1911, 1915, and 1917 of 23S rRNA to pseudouridines. These nucleotides are located in the functionally important helix‐loop 69 of 23S rRNA. RluD is the only pseudouridine synthase that is required for normal growth in Escherichia coli. We have analyzed substrate specificity of RluD in vivo. Mutational analyses have revealed: (a) RluD isomerizes uridine in vivo only at positions 1911, 1915, and 1917, regardless of the presence of uridine at other positions in the loop of helix 69 of 23S rRNA variants; (b) substitution of one U by C has no effect on the conversion of others (i.e. formation of pseudouridines at positions 1911, 1915, and 1917 are independent of each other); (c) A1916 is the only position in the loop of helix 69, where mutations affect the RluD specific pseudouridine formation. Pseudouridines were determined in the ribosomal particles from a ribosomal large subunit defective strain (RNA helicase DeaD–). An absence of pseudouridines in the assembly precursor particles suggests that RluD directed isomerization of uridines occurs as a late step during the assembly of the large ribosomal subunit.
Immediate versus delayed chemotherapy in patients with asymptomatic incurable metastatic cancer
Authors: CARDEN Craig P , ROSENTHAL Mark A
Published: October 2007

Aim:  To examine the evidence of benefit in initiating immediate chemotherapy in patients with newly diagnosed asymptomatic metastatic incurable cancer, compared with delaying chemotherapy until symptomatic progression.

Methods:  Through an extensive review of published reports, we examined the biological, clinical, psychological and ethical background of the issue and reported on the available clinical trial evidence in a variety of tumor types.

Results:  Only a limited number of clinical trials have directly examined the role of immediate versus delayed chemotherapy in patients with incurable asymptomatic metastatic cancer. Small studies in mesothelioma, colorectal cancer, breast cancer, myeloma, and low‐grade lymphoma suggest no survival benefit for the immediate initiation of chemotherapy. However, there was no evidence in other tumor types.

Conclusion:  The appropriate timing of chemotherapy initiation in an asymptomatic patient with metastatic cancer remains a substantial question in oncology. Many factors are likely to impact on the decision. However, little if any evidence demonstrates a clear advantage in the immediate initiation of chemotherapy in this setting.
Prevalence of distress in cancer patients undergoing chemotherapy
Authors: ZAINAL Nor , HUI Koh , HANG Ting , BUSTAM Anita
Published: October 2007

Aim:  Feeling distressed is often a normal reaction to the diagnosis of cancer and cancer treatment. However, if excessive, distress may lead to more disabling conditions such as depression and anxiety. The aims of the study were to determine the prevalence and level of distress in patients with cancer who were undergoing chemotherapy and to examine the associated factors related to psychological distress in these patients.

Methods:  Adult patients with confirmed cancer who were undergoing out‐patient chemotherapy at the Clinical Oncology Unit, Universiti Malaya Medical Centre were invited to participate in the study. They were assessed on their sociodemographic profiles, clinical history, distress level as measured using the ‘Distress Thermometer’, and problems checklist on practical, family, emotional and physical symptoms. The Hospital Anxiety Depression Scale (HADS) was used by patients to report anxiety and depression.

Results:  One hundred and sixty‐eight patients with mean age of 50 years participated in the study. The prevalence of psychological distress determined by the ‘Distress Thermometer’ was 51%. HADS found the prevalence of depression/anxiety to be 32%. There was no significant association between distress and the primary site of cancer, the phase of chemotherapy and the sociodemographic profiles except for age (r = −0.21, P = 0.007). Distress was significantly associated with practical, family and emotional problems. Some of the physical problems such as appearance, breathing, changes in urination, constipation, eating, fatigue, getting around, memory/concentration, nausea, pain and sleep were also significantly associated with distress.

Conclusion:  Cancer patients undergoing chemotherapy experienced high level of distress. This finding should alert oncologists that some patients exhibiting these signs of distress may need referral to the mental health team.
Asteroseismology of red giants: photometric observations of Arcturus by SMEI
Authors: Tarrant N. J. , Chaplin W. J. , Elsworth Y. , Spreckley S. A. , Stevens I. R.
Published: October 2007

We present new results on oscillations of the K1.5 III giant Arcturus (α Boo), from analysis of just over 2.5 yr of precise photometric observations made by the Solar Mass Ejection Imager on board the Coriolis satellite. A strong mode of oscillation is uncovered by the analysis, having frequency 3.51 ± 0.03 μHz. By fitting its mode peak, we are able to offer a highly constrained direct estimate of the damping time (τ= 24 ± 1 d). The data also hint at the possible presence of several radial-mode overtones, and maybe some non-radial modes. We are also able to measure the properties of the granulation on the star, with the characteristic time-scale for the granulation estimated to be ∼0.50 ± 0.05 d.
EXPOSURE OF LISTERIA MONOCYTOGENES TO FOOD AND TEMPERATURE ABUSE USING A DIALYSIS TUBING CULTURE METHOD
Authors: PANG HOAN‐JEN , POTENSKI CATHERINE J. , MATTHEWS KARL R.
Published: October 2007

Foodborne illnesses are often linked to foods that have been contaminated postprocessing and exposed to temperature abuse conditions prior to consumption. Limitations in methods to recover sufficient numbers of a target bacterium from an (inoculated) intentionally contaminated food can hinder genomic/proteomic analysis, and in conducting in vitro assays using the recovered cells. In this study, a dialysis tubing culture technique was developed to facilitate the recovery of high numbers of Listeria monocytogenes exposed to temperature abuse while in association with chocolate milk and frankfurter slurry. The impact of exposure to foods, followed by temperature abuse, on the virulence of L. monocytogenes was investigated using the Caco‐2 cell infection assay. The expression of groEL, associated with stress, was also determined. L. monocytogenes inoculated into brain–heart infusion (BHI) broth (control), chocolate milk or frankfurter slurry was held at 4C for 24 h to simulate short‐term exposure to each food. The L. monocytogenes‐contaminated food was then exposed to a series of temperature shifts to simulate temperature abuse. The final temperature of the abused BHI and chocolate milk was 30C, and the frankfurter slurry was 22C. The stress response gene, groEL, was only induced in the control cells (suspended in BHI) after they had been exposed to temperature abuse conditions. The expression of groEL was also evident in cells exposed to foods and temperature abuse conditions, suggesting that the foods used in this study were a stressful environment for the cells. This study showed that the exposure of L. monocytogenes to chocolate milk or frankfurter slurry, or temperature abuse has no impact on the virulence of L. monocytogenes as demonstrated using the Caco‐2 cell assay. However, the expression of groEL suggests that the foods evaluated can be stressful environments for L. monocytogenes despite its ability to grow or survive in those foods. The dialysis tubing culture technique developed is a simple and highly cost‐effective method for exposure of bacteria to food and the recovery of a large number of cells suitable for additional analysis.
INCIDENCE OF LISTERIA SPECIES IN SEAFOOD PRODUCTS OF MYSORE, INDIA
Authors: MOHAREM AHMED SAIF , RAJ A.P. CHARITH , JANARDHANA G.R.
Published: October 2007

Listeria monocytogenes is one of the most important foodborne pathogens causing illness in humans and animals. Thus, a study was undertaken to investigate the incidence of Listeria species in fresh and dry fish samples marketed in Mysore, India. A total of 164 fresh and dry fish samples collected from retail outlet shops of Mysore, South India, during the period August 2005 through August 2006 were examined for the presence of Listeria species by using ISO 11290 protocol. The incidence of Listeria species was positive in 62 samples (37.8%), and L. monocytogenes was isolated from only three (1.83%) fresh fish samples. Listeria species in seafood were predominant in the order of Listeria innocua (50) (30.49%), Listeria grayi (eight) (4.9%), L. monocytogenes (three) (1.83%) and Listeria seeligeri (one) (0.6%). All isolates of Listeria species were subjected to polymerase chain reaction (PCR) and confirmed with the genus‐specific set of primers, and special emphasis was given for detection of L. monocytogenes using a species‐specific set of primers. The specificity and sensitivity of PCR were in good correlation with the cultural methods. The results indicated a high incidence of Listeria species and L. monocytogenes in fresh fish samples. This warrants the need for appropriate control measures as this would pose a serious threat to human health.
EFFECTS OF BIFIDOCIN B AND LACTOCOCCIN R ON THE GROWTH OF LISTERIA MONOCYTOGENES AND BACILLUS CEREUS ON STERILE CHICKEN BREAST
Authors: YILDIRIM ZELIHA , YILDIRIM METIN , JOHNSON MICHAEL G.
Published: October 2007

In the study, the efficacies of bifidocin B and lactococcin R produced by Bifidobacterium bifidum and Lactococcus lactis subsp. cremoris R to control Listeria monocytogenes or Bacillus cereus in irradiated raw chicken breast during storage at 5–8C for 28 days or at 22–25C for 24 h were determined. Each irradiated raw chicken breast was inoculated with 106 cfu/g L. monocytogenes or B. cereus. It was found that both bacteriocins were more effective against L. monocytogenes or B. cereus at 5–8C than at 22–25C, and that lactococcin R was more inhibitory than bifidocin B. Challenge study analysis demonstrated that incorporation of bifidocin B or lactococcin R at a level of 1,600 or 3,200 AU/g could effectively inhibit the growth of L. monocytogenes or B. cereus for 3–4 weeks at 5–8C or 6–12 h at 22–25C.
INCIDENCE AND CHARACTERIZATION OF SALMONELLA SPECIES IN STREET FOOD AND CLINICAL SAMPLES
Authors: TUNUNG R. , CHAI L.C. , USHA M.R. , LESLEY M.B. , CHEAH Y.K. , PATRICK G.B. , FARINAZLEEN M.G. , FATIMAH A.B. , MALAKAR P.K. , SON R.
Published: October 2007

The objectives of our study were to investigate the Salmonella species contamination in various types of ready‐to‐eat street‐vended dishes or drinks, to isolate Salmonella spp. from clinical samples and to assess the possible relationship between the serotypes isolated from these two different environments. The isolates were characterized by their antibiotic resistance, plasmid profiles and randomly amplified polymorphic DNA (RAPD) sequences. A total of 24 salmonellae, belonging to seven different serotypes, were isolated from 129 different street‐vended foods and drinks and 12 clinical samples (rectal swabs). The encountered serotypes from street foods were Salmonella Biafra (n = 8), Salmonella Braenderup (n = 3) and Salmonella Weltevreden (n = 1), and from clinical samples were Salmonella Typhi (n = 8), Salmonella Typhimurium (n = 2), Salmonella Paratyphi A (n = 1) and Salmonella Paratyphi B (n = 1). The results showed no similarities in the types of Salmonella serotypes from street food and clinical samples examined. The Salmonella strains were resistant to one or more of the 14 tested antibiotics. Seventeen isolates harbored plasmids, with plasmid sizes ranging from 3.0 to 38.5 MDa. RAPD fingerprinting with primers OPAR3 and OPAR8 produced a combination of 21 fingerprint patterns. The dendrograms generated for the S. Biafra and S. Typhi showed strains of the same serotypes but of very different types of sample and location of sampling clustered together, indicating the possibility of cross contamination during food handling.
BEHAVIOR OF STAPHYLOCOCCUS AUREUS IN SUCUK WITH NETTLE (URTICA DIOICA L.)
Authors: KABAN GÜZİN , AKSU MUHAMMET İRFAN , KAYA MÜKERREM
Published: October 2007

The behavior of Staphylococcus aureus was studied in sucuk (Turkish dry fermented sausage) with different levels of nettle (Urtica dioica L.). Sucuk batters containing different levels (1, 3 and 5%) of nettle were prepared and contaminated with S. aureus at approximately 104 cfu/g. Sucuk batter not inoculated with S. aureus and not containing nettle addition was set as the control lot. Lactobacillus sakei Lb 706 was used as a starter culture. During ripening period, S. aureus, Micrococcus/Staphylococcus and lactic acid bacteria counts were determined. pH and water activity (aw) values were also analyzed.

The S. aureus count was under detectable levels in the control lot, and the pH level dropped below 5.0 after the first 24 h of fermentation. Initial pH values increased gradually in all three lots (1, 3 and 5%). At the end of the first 24 h of fermentation, a significant increase in S. aureus counts was determined in all lots of sausage except for the control lot. The pH value of the sucuk sample containing 1% nettle was under 5.0 on the second day. However, pH values for sucuk samples containing 3 and 5% nettle did not drop below 5.0 during the ripening period, including the fermentation phase. Nettle usage had no effect on the lactic acid bacteria count; however, it had significant effects on the Micrococcus/Staphylococcus count and aw value.
Urinary incontinence – meeting a transcultural challenge in Sydney, Australia
Authors: Ip Virginia , Busuttil Leaver Rachel
Published: October 2007

The universal phenomenon of immigration is a continuous reality in many developed countries. As a consequence, nurses and other health professionals are expected to recognize, understand, take action and interact favourably with people from diverse cultural backgrounds . Nurses need to become culturally competent and develop their knowledge, skills, behaviours and values in transcultural nursing in order to deliver optimum care to the multiethnic cultures accessing health care. However, the combination of a paucity of systematic research and the lack of formal education programmes has resulted in poor development in this area. Many concepts relevant to cross‐culture are poorly understood, valued and studied. The first author describes how she established a urology/continence nurse‐led clinic for local non‐English speaking Chinese residents in South East Sydney. The authors give recommendations for nurses who wish to establish similar clinics to provide culture‐specific urological and continence care required for multiethnic populations.
Patient attitudes to nursing students in urology outpatients
Authors: Bromage Stephen James , Hu Jingy , Ladds Thomas , Robinson Elaine , Pearce Ian
Published: October 2007

Urological conditions are increasingly being managed in an outpatient setting and this environment can offer valuable training in urology nursing particularly with the emergence of nurse‐led clinics. Patient attitudes to nursing students may influence the effectiveness of these training opportunities. We set out to determine patient attitudes to nursing students in urology outpatients and whether opinions are related to patient age, ethnicity or prior exposure to students. Questionnaires were given to all patients attending urology outpatient clinics until 500 completed questionnaires were collected. The questionnaire consisted of nine questions concerning patient demographics and attitudes towards the presence of nursing students. Patients were also asked to grade their comfort with a student’s presence from 0, indicating very comfortable, to 10, indicating very uncomfortable. Only 12% of patients had some degree of objection to the presence of student nurses and most patients (72%) had no preference as to the student gender. When means were derived for patients’ acceptance of the presence of student nurses, there was a significantly lower mean score, indicating more acceptance in patients aged over 30 years compared with those aged under 30 years (p ≤ 0·0001). This also applied to those who spoke English as their first language compared with those who did not (p = 0·063), and to those who had previously been exposed to nursing students compared with those with no exposure (p = 0·0002). Overall, patients were comfortable with nursing students attending their urological outpatient assessment. The patient groups that objected the most were those under the age of 30 years, those who did not speak English as their first language and those with no prior exposure to students.
Inclusive nursing care for people with intellectual disabilities using urology services
Authors: Barr Owen , Sowney Margaret
Published: October 2007

The need to address the health needs and provide equity of access to health care for people with intellectual disabilities has been highlighted nationally within the UK, as well as internationally. Despite a similar likelihood (if not an increased likelihood) of urological problems among people with intellectual disabilities, this topic appears to have received limited attention within the wider nursing or the specific intellectual disability literature. This paper considers the potential challenges that may be encountered in seeking to provide care and support a person with intellectual disabilities who may require the support of a urology nurse and provides some suggestions for practical actions to respond effectively.
General practitioners’ perceptions of a community‐based nurse‐led assessment clinic for patients with benign prostatic hyperplasia
Authors: McCaughan Eilis , Parahoo Kader , Thompson Kathryn , Reid Stuart
Published: October 2007

The prevalence of benign prostatic hyperplasia (BPH) increases with age; therefore, this condition is likely to rise as people live longer. This poses challenges in how best health services can be organized to diagnose, treat or manage this disease effectively. A community‐based nurse‐led clinic was set up to assess and advice people with BPH who were referred by general practitioners (GPs). The aim of this study was to explore the perceptions of GPs of the value and benefits of the nurse‐led BPH clinic. Two focus groups were carried out with a random sample of 10 GPs (five in each group). The findings showed that the assessment carried out at the clinic by the specialist nurse helped them to avoid the ‘trial and error’ approach that GPs sometimes used in treating this condition. Although they did not find that the clinic reduced their (GPs) workload, it offered a valuable, enhanced service to help them make accurate diagnosis and prescribe appropriately, thereby contributing to the quality of life of patients. This study showed that nurses’ and doctors’ work can complement each other to the benefit of patients. It adds to the growing evidence that appropriate skill mix can contribute to effective practice.
Intracellular calcium changes in mice Leydig cells are dependent on calcium entry through T‐type calcium channels
Authors: Costa Roberta Ribeiro , Varanda Wamberto Antonio
Published: October 2007

Luteinizing hormone (LH) regulates testosterone synthesis in Leydig cells by inducing an intracellular increase in cAMP concentration. LH also increases the intracellular calcium concentration ([Ca2+]i), dependent on the presence of Ca2+ in the extracellular medium ([Ca2+]e) for its effect. Despite these evidences, the identity of a pathway for calcium entry has remained elusive and the relationship between cAMP and [Ca2+]i has been questioned. Here we show that mice Leydig cells do have an inward Ca2+ current carried by T‐type Ca2+ channels. In 10 mm[Ca2+]e, the currents start to be activated at −60 mV, reaching maximal amplitude of 1.8 ± 0.3 pA pF−1 at −20 mV. Currents were not modified by Ba2+ or Sr2+, were suppressed in Ca2+‐free external solution, and were blocked by 100 μm nickel or 100 μm cadmium. The Ki for Ni2+ is 2.6 μm and concentrations of Cd2+ smaller than 50 μm have a very small effect on the currents. The calcium currents displayed a window centred at −40 mV. The half‐voltage (V0.5) of activation is −30.3 mV, whereas the half‐voltage steady‐state inactivation is −51.1 mV. The deactivation time constant (τdeactivation) is around 3 ms at −35 mV. Confocal microscopy experiments with Fluo‐3 loaded cells reveal that both LH and dibutyryl‐cAMP (db‐cAMP) increase [Ca2+]i. The db‐cAMP induced calcium increase was dependent on Ca2+ influx since it was abolished by removal of extracellular Ca2+ and by 400 μm Ni2+. [Ca2+]i increases in regions close to the plasma membrane and in the cell nucleus. Similar effects are seen when Leydig cells are depolarized by withdrawing K+ from the extracellular solution. Altogether, our studies show that Ca2+ influx through T‐type Ca2+ channels in the plasma membrane of Leydig cells plays a crucial role in the intracellular calcium concentration changes that follow binding of LH to its receptor.
Multiphoton imaging of chick retinal development in relation to gap junctional communication
Authors: Becker David L. , Webb Kevin F. , Thrasivoulou Christopher , Lin Chih‐Chi , Nadershahi Roxana , Tsakiri Niki , Cook Jeremy E.
Published: October 2007

Neural progenitor cells in the developing retina extend processes that stretch from the basal vitread surface to the apical ventricular surface. During the cell cycle, the nucleus undergoes interkinetic nuclear migration (INM), moving in a vitread direction during G1, passing through S‐phase at its peak and then, on entering G2, returning towards the ventricular surface where it enters M‐phase and divides. We have previously shown that individual saltatory movements of the nucleus correlate with transient changes in cytosolic calcium concentration within these progenitor cells and that these events spread to neighbouring progenitors through connexin43 (Cx43) gap junction channels, thereby coordinating the migration of coupled clusters of cells. Disrupting coupling with pharmacological agents, Cx43‐specific antisense oligodeoxynucleotides (asODNs) or dominant negative Cx43 (dnCx43) inhibits the sharing of calcium events, reducing the number that each cell experiences and significantly slowing INM. We have developed protocols for imaging migrating progenitor cells by confocal microscopy over relatively short periods, and by multiphoton microscopy over more extended periods that include complete cell cycles. We find that perturbing gap junctional communication not only slows the INM of progenitor cells but also apparently prevents them from changing direction at critical phases of the cell cycle. It also disrupts the migration of young neurons to their appropriate layers after terminal division and leads to their ectopic differentiation. The ability to perform extended time‐lapse imaging over 3D volumes in living retina using multiphoton microscopy should now allow fundamental mechanisms governing development of the retinal neuroepithelium to be probed in detail.
Effects of the menstrual cycle on sympathetic neural responses to mental stress in humans
Authors: Carter Jason R. , Lawrence Johnathan E.
Published: October 2007

The influence of the menstrual cycle on resting muscle sympathetic nerve activity (MSNA) remains controversial, and the effect of the menstrual cycle on MSNA responses to mental stress is unknown. We examined MSNA, mean arterial pressure (MAP), and heart rate (HR) responses to mental stress (via mental arithmetic) in 11 healthy females during the early follicular (EF) and mid‐luteal (ML) phases of the menstrual cycle. The menstrual cycle did not alter resting MSNA (EF, 13 ± 3 bursts min−1versus ML, 13 ± 2 bursts min−1), MAP (EF, 79 ± 3 mmHg versus ML, 81 ± 2 mmHg) and HR (EF, 66 ± 3 beats min−1versus ML, 64 ± 2 beats min−1). 5 min of mental stress increased MSNA, MAP and HR during both the EF (Δ4 ± 2 bursts min−1, Δ12 ± 2 mmHg, Δ18 ± 2 beats min−1; P < 0.05) and ML (Δ4 ± 2 bursts min−1, Δ13 ± 3 mmHg and Δ20 ± 2 beats min−1; P < 0.05) phases. These responses were not different between phases. In contrast, MSNA responses were different between phases during the 10 min recovery from mental stress. MSNA remained elevated during the initial 5 min of recovery in both the EF (Δ6 ± 1 bursts min−1; P < 0.01) and ML (Δ7 ± 1 bursts min−1; P < 0.01) phases, but only remained elevated during the ML phase (Δ6 ± 1 bursts min−1; P < 0.01) during the final 5 min of recovery. Our results demonstrate that MSNA, MAP and HR responses at rest or during mental stress are not different during the EF and ML phases of the menstrual cycle in young, healthy females. However, MSNA activation during recovery from mental stress is prolonged during the ML phase compared to the EF phase.
The cerebral metabolic ratio is not affected by oxygen availability during maximal exercise in humans
Authors: Volianitis S. , Fabricius‐Bjerre A. , Overgaard A. , Strømstad M. , Bjarrum M. , Carlson C. , Petersen N. T. , Rasmussen P. , Secher N. H. , Nielsen H. B.
Published: October 2007

Intense exercise decreases the cerebral metabolic ratio of O2 to carbohydrates (glucose +½ lactate) and the cerebral lactate uptake depends on its arterial concentration, but whether these variables are influenced by O2 availability is not known. In six males, maximal ergometer rowing increased the arterial lactate to 21.4 ± 0.8 mm (mean ±s.e.m.) and arterial–jugular venous (a–v) difference from −0.03 ± 0.01 mm at rest to 2.52 ± 0.03 mm (P < 0.05). Arterial glucose was raised to 8.5 ± 0.5 mm and its a–v difference increased from 1.03 ± 0.01 to 1.86 ± 0.02 mm (P < 0.05) in the immediate recovery. During exercise, the cerebral metabolic ratio decreased from 5.67 ± 0.52 at rest to 1.70 ± 0.23 (P < 0.05) and remained low in the early recovery. Arterial haemoglobin O2 saturation was 92.5 ± 0.2% during exercise with room air, and it reached 87.6 ± 1.0% and 98.9 ± 0.2% during exercise with an inspired O2 fraction of 0.17 and 0.30, respectively. Whilst the increase in a–v lactate difference was attenuated by manipulation of cerebral O2 availability, the cerebral metabolic ratio was not affected significantly. During maximal rowing, the cerebral metabolic ratio reaches the lowest value with no effect by a moderate change in the arterial O2 content. These findings suggest that intense whole body exercise is associated with marked imbalance in the cerebral metabolic substrate preferences independent of oxygen availability.
Voltage and calcium transients in basal dendrites of the rat prefrontal cortex
Authors: Milojkovic Bogdan A. , Zhou Wen‐Liang , Antic Srdjan D.
Published: October 2007

Higher cortical functions (perception, cognition, learning and memory) are in large part based on the integration of electrical and calcium signals that takes place in thin dendritic branches of neocortical pyramidal cells (synaptic integration). The mechanisms underlying the synaptic integration in thin basal dendrites are largely unexplored. We use a recently developed technique, multisite voltage–calcium imaging, to compare voltage and calcium transients from multiple locations along individual dendritic branches. Our results reveal characteristic electrical transients (plateau potentials) that trigger and shape dendritic calcium dynamics and calcium distribution during suprathreshold glutamatergic synaptic input. We regularly observed three classes of voltage–calcium interactions occurring simultaneously in three different zones of the same dendritic branch: (1) proximal to the input site, (2) at the input site, and (3) distal to the input site. One hundred micrometers away from the synaptic input site, both proximally and distally, dendritic calcium transients are in tight temporal correlation with the dendritic plateau potential. However, on the same dendrite, at the location of excitatory input, calcium transients outlast local dendritic plateau potentials by severalfold. These Ca2+ plateaus (duration 0.5–2 s) are spatially restricted to the synaptic input site, where they cause a brief down‐regulation of dendritic excitability. Ca2+ plateaus are not mediated by Ca2+ release from intracellular stores, but rather by an NMDA‐dependent small‐amplitude depolarization, which persists after the collapse of the dendritic plateau potential. These unique features of dendritic voltage and calcium distributions may provide distinct zones for simultaneous long‐term (bidirectional) modulation of synaptic contacts along the same basal branch.
Age‐related change in duration of afterhyperpolarization of human motoneurones
Authors: Piotrkiewicz M. , Kudina L. , Mierzejewska J. , Jakubiec M. , Hausmanowa‐Petrusewicz I.
Published: October 2007

Motor unit (MU) potentials were recorded from brachial biceps of healthy subjects aged 5.5–79 years. The subjects were subdivided into young (5.5–19 year) and adult (37.5–79 year) groups, between which single MU discharge characteristics were compared. Firing rates were in the ranges of 8.3–21.7 s−1 (mean 12.87 s−1) and 5.9–18.7 s−1 (mean 11.08 s−1) for young and adult groups, respectively. Standard deviations (s.d.) of interspike intervals (ISIs) were in the range 4.84–11.57 ms (mean 8.39 ms) for the young group and 4.26–12.23 ms (mean 7.76 ms) for the adult group. Both differences were statistically significant (P < 0.001). Special attention was paid to the previously developed method of ISI variability analysis, which enabled the comparison of MUs with respect to afterhyperpolarization (AHP) duration of their motoneurones (MNs). The results show that AHP duration increases gradually with increasing age, which is in line with the transformation of muscle properties towards a slower phenotype. This transformation seems to be a continuous process, covering the entire lifespan of a human being, from childhood to senescence. The results presented here are significant for their insight into the ageing process of the neuromuscular system. The age‐related change in AHP duration has not been investigated previously in human studies and has been met with ambiguous results in animal studies.
Endothelium‐derived hyperpolarizing factor as an in vivo back‐up mechanism in the cutaneous microcirculation in old mice
Authors: Gaubert Marie Line , Sigaudo‐Roussel Dominique , Tartas Maylis , Berrut Gilles , Saumet Jean Louis , Fromy Bérengère
Published: October 2007

There is now strong evidence that an endothelium‐derived hyperpolarizing factor (EDHF), other than nitric oxide (NO) or prostaglandin (PG), exists for dilating arteries and arterioles. In vitro studies on isolated vessels pointed out a role for EDHF as a back‐up mechanism when the NO pathway is impaired, but there was a lack of in vivo studies showing a functional role for EDHF. Ageing has pronounced effects on vascular function and particularly on endothelium‐dependent relaxation, providing a novel situation in which to assess the contributions of EDHF. The purpose of the present study was thus to determine if, in vivo, there was a functional role for EDHF as a back‐up mechanism in the cutaneous microcirculation in the ageing process. We investigated in vivo the contribution of each endothelial factor (NO, PG and EDHF) in the cutaneous vasodilatation induced by iontophoretic delivery of acetylcholine and local pressure application in young adult (6–7 months) and old (22–25 months) mice, using pharmacological inhibitors. The cutaneous vasodilator responses induced by acetylcholine and local pressure application were dependent upon NO and PG pathways in young adult mice, whereas they were EDHF‐dependent in old mice. EDHF appears to serve as a back‐up mechanism when ageing reaches pathological states in terms of the ability for NO and PG to relax cutaneous microvessels, allowing for persistent cutaneous vasodilatator responses in old mice. However, as a back‐up mechanism, EDHF did not completely restore cutaneous vasodilatation, since endothelial responses were reduced in old mice compared to young adult mice.
Role of the S6 C‐terminus in KCNQ1 channel gating
Authors: Boulet Inge R. , Labro Alain J. , Raes Adam L. , Snyders Dirk J.
Published: October 2007

Co‐assembly of KCNQ1 α‐subunits with KCNE1 β‐subunits results in the channel complex underlying the cardiac IKs current in vivo. Like other voltage‐gated K+ channels, KCNQ1 has a tetrameric configuration. The S6 segment of each subunit lines the ion channel pore with the lower part forming the activation gate. To determine residues involved in protein–protein interactions in the C‐terminal part of S6 (S6T), alanine and tryptophan perturbation scans were performed from residue 348–362 in the KCNQ1 channel. Several residues were identified to be relevant in channel gating, as substitutions affected the activation and/or deactivation process. Some mutations (F351A and V355W) drastically altered the gating characteristics of the resultant KCNQ1 channel, to the point of mimicking the IKs current. Furthermore, mutagenesis of residue L353 to an alanine or a charged residue impaired normal channel closure upon hyperpolarization, generating a constitutively open phenotype. This indicates that the L353 residue is essential for stabilizing the closed conformation of the channel gate. These findings together with the identification of several LQT1 mutations in the S6 C‐terminus of KCNQ1 underscore the relevance of this region in KCNQ1 and IKs channel gating.
The Genomic Landscapes of Human Breast and Colorectal Cancers
Authors: Wood Laura D. , Parsons D. Williams , Jones Siân , Lin Jimmy , Sjöblom Tobias , Leary Rebecca J. , Shen Dong , Boca Simina M. , Barber Thomas , Ptak Janine , Silliman Natalie , Szabo Steve , Dezso Zoltan , Ustyanksky Vadim , Nikolskaya Tatiana , Nikolsky Yuri , Karchin Rachel , Wilson Paul A. , Kaminker Joshua S. , Zhang Zemin , Croshaw Randal , Willis Joseph , Dawson Dawn , Shipitsin Michail , Willson James K. V. , Sukumar Saraswati , Polyak Kornelia , Park Ben Ho , Pethiyagoda Charit L. , Pant P. V. Krishna , Ballinger Dennis G. , Sparks Andrew B. , Hartigan James , Smith Douglas R. , Suh Erick , Papadopoulos Nickolas , Buckhaults Phillip , Markowitz Sanford D. , Parmigiani Giovanni , Kinzler Kenneth W. , Velculescu Victor E. , Vogelstein Bert
Published: October 2007

Human cancer is caused by the accumulation of mutations in oncogenes and tumor suppressor genes. To catalog the genetic changes that occur during tumorigenesis, we isolated DNA from 11 breast and 11 colorectal tumors and determined the sequences of the genes in the Reference Sequence database in these samples. Based on analysis of exons representing 20,857 transcripts from 18,191 genes, we conclude that the genomic landscapes of breast and colorectal cancers are composed of a handful of commonly mutated gene “mountains” and a much larger number of gene “hills” that are mutated at low frequency. We describe statistical and bioinformatic tools that may help identify mutations with a role in tumorigenesis. These results have implications for understanding the nature and heterogeneity of human cancers and for using personal genomics for tumor diagnosis and therapy.
Widespread Morning Drizzle on Titan
Authors: Ádámkovics Máté , Wong Michael H. , Laver Conor , de Pater Imke
Published: October 2007

Precipitation is expected in Titan's atmosphere, yet it has not been directly observed, and the geographical regions where rain occurs are unknown. Here we present near-infrared spectra from the Very Large Telescope and W. M. Keck Observatories that reveal an enhancement of opacity in Titan's troposphere on the morning side of the leading hemisphere. Retrieved extinction profiles are consistent with condensed methane in clouds at an altitude near 30 kilometers and concomitant methane drizzle below. The moisture encompasses the equatorial region over Titan's brightest continent, Xanadu. Diurnal temperature gradients that cause variations in methane relative humidity, winds, and topography may each be a contributing factor to the condensation mechanism. The clouds and precipitation are optically thin at 2.0 micrometers, and models of “subvisible” clouds suggest that the droplets are 0.1 millimeter or larger.
Orbital Reconstruction and Covalent Bonding at an Oxide Interface
Authors: Chakhalian J. , Freeland J. W. , Habermeier H.-U. , Cristiani G. , Khaliullin G. , van Veenendaal M. , Keimer B.
Published: October 2007

Orbital reconstructions and covalent bonding must be considered as important factors in the rational design of oxide heterostructures with engineered physical properties. We have investigated the interface between high-temperature superconducting (Y,Ca)Ba
2
Cu
3
O
7
and metallic La
0.67
Ca
0.33
MnO
3
by resonant x-ray spectroscopy. A charge of about –0.2 electron is transferred from Mn to Cu ions across the interface and induces a major reconstruction of the orbital occupation and orbital symmetry in the interfacial CuO
2
layers. In particular, the Cu
d

3
z
2
–
r
2

orbital, which is fully occupied and electronically inactive in the bulk, is partially occupied at the interface. Supported by exact-diagonalization calculations, these data indicate the formation of a strong chemical bond between Cu and Mn atoms across the interface. Orbital reconstructions and associated covalent bonding are thus important factors in determining the physical properties of oxide heterostructures.
Human Infection withFusobacterium necrophorum(Necrobacillosis), with a Focus on Lemierre's Syndrome
Authors: Riordan Terry
Published: October 2007

Summary:Human infection withFusobacterium necrophorumusually involvesF. necrophorumsubsp.funduliformerather thanF. necrophorumsubsp.necrophorum, which is a common pathogen in animals. Lemierre's syndrome, or postanginal sepsis, is the most common life-threatening manifestation. Tonsillitis is followed by septic thrombophlebitis of the internal jugular vein and then a septicemia with septic emboli in lungs and other sites. Recent evidence suggests thatF. necrophorumcan be limited to the throat and cause persistent or recurrent tonsillitis.F. necrophorumis unique among non-spore-forming anaerobes, first for its virulence and association with Lemierre's syndrome as a monomicrobial infection and second because it seems probable that it is an exogenously acquired infection. The source of infection is unclear; suggestions include acquisition from animals or human-to-human transmission. Approximately 10% of published cases are associated with infectious mononucleosis, which may facilitate invasion. Recent work suggests that underlying thrombophilia may predispose to internal jugular vein thrombophlebitis. Lemierre's syndrome was relatively common in the preantibiotic era but seemed to virtually disappear with widespread use of antibiotics for upper respiratory tract infection. In the last 15 years there has been a rise in incidence, possibly related to restriction in antibiotic use for sore throat.
Type III Secretion Systems and Disease
Authors: Coburn Bryan , Sekirov Inna , Finlay B. Brett
Published: October 2007

Type III secretion systems (T3SSs) are complex bacterial structures that provide gram-negative pathogens with a unique virulence mechanism enabling them to inject bacterial effector proteins directly into the host cell cytoplasm, bypassing the extracellular milieu. Although the effector proteins vary among different T3SS pathogens, common pathogenic mechanisms emerge, including interference with the host cell cytoskeleton to promote attachment and invasion, interference with cellular trafficking processes, cytotoxicity and barrier dysfunction, and immune system subversion. The activity of the T3SSs correlates closely with infection progression and outcome, both in animal models and in human infection. Therefore, to facilitate patient care and improve outcomes, it is important to understand the T3SS-mediated virulence processes and to target T3SSs in therapeutic and prophylactic development efforts.