bluuebunny/crossref_metadata_2025 huggingface dataset:
Recent increases in species richness and shifts in altitudinal distributions of Norwegian mountain plants
Authors: Klanderud Kari , Birks H. J. B.
Published: February 2003

Opportunities for observing long-term changes in natural biota are rare. Observations on the distribution and frequency of vascular plants were performed on 23 mountains situated along a west–east gradient in Jotunhei men, central Norway, where detailed site descriptions and species lists exist from ad 1930–31. The sites were resurveyed during the summer of 1998, to examine possible changes in species richness and species distributions along the altitudinal gradient during a 68-year period. Increased species richness was found on 19 of the mountains and was most pronounced at lower altitudes and in the eastern areas. Lowland species, dwarf shrubs and species with wide altitudinal and ecological ranges showed the greatest increases in abundance and altitudinal advances since the 1930–31 study. Species with more restricted habitat demands, such as some hygrophilous snow-bed species, have declined. High-altitude species have disappeared from their lower-elevation sites and increased their abundance at the highest altitudes. Climatic warming occurring in the last 100 years might have allowed the invasion of lowland and lee-slope species. Increased competition at sites where such species have invaded may have led to a decreased abundance of the less competitive species and a concentration of high-altitude species on the highest ridges. Natural succession since the ‘Little Ice Age’, increased deposition of nitrogen during recent years and changes in grazing and tourism might have in‘ uenced some of the species turnovers, but recent climatic changes are considered to be the most likely major driving factor for the changes observed.
Microfossil evidence for land movements associated with the AD 1964 Alaska earthquake
Authors: Zong Y. , Shennan I. , Combellick R. A. , Hamilton S. L. , Rutherford M. M.
Published: February 2003

Microfossil diatom and pollen data from a number of cores at coastal marshes at Girdwood Flats and Kenai Flats in Cook Inlet, Alaska, suggest that there was a phase of gradual land subsidence prior to the main shock of the ad 1964 earthquake. This phase followed a long period of gradual land uplift since the last large earthquake, which occurred about 730–900 years ago. Caesium (137Cs) records indicate that subsidence started approximately 15 years before the 1964 earthquake. This pre-seismic subsidence is evident in the coastal marsh sediment sequences in changes in diatom and pollen assemblages that indicate changes in tidal-marsh environments or a change from raised-bog to marsh conditions. The microfossil evidence indicates|0.15 m pre-seismic land subsidence at both Girdwood Flats and Kenai Flats and co-seismic subsidence of|1.8 m and|0.2 m respectively.
Sedimentary charcoal as an indicator of late-Holocene drought in the Sierra Nevada, California, and its relevance to the future
Authors: Brunelle Andrea , Anderson R. Scott
Published: February 2003

A Holocene record of climate, fire and vegetation regimes was reconstructed for Siesta Lake, Yosemite National Park, California, using fossil pollen and charcoal from lake sediments. These reconstructions were generated to provide a long-term perspective on drought in the Sierra Nevada. The sedimentary record is in agreement with other long-term records of climate and vegetation from the Sierra Nevada, and the records of climate and fire for the last c. 1000 years are in agreement with tree-ring and hydrological studies. This correspondence suggests that sedimentary charcoal and pollen are reliable indicators of change in climate, vegetation and fire frequency through time. The fire frequencies associated with the droughts of the ‘Mediaeval Warm Period’ are only half as great as those recorded during the early-Holocene insolation maximum. Model results suggest that the temperature increases associated with the insolation maximum are a good analogue for those expected with global warming. If this is the case, future droughts may be more severe than any experi enced in the last several thousand years, and these data should be considered in planning for future change.
A ‘clam-ring’ master-chronology constructed from a short-lived bivalve mollusc from the northern Gulf of California, USA
Authors: Schöne Bernd R.
Published: February 2003

Age-detrended and standardized annual growth increment width time series of 67 live-collected intertidal bivalve molluscs of the species Chione cortezi, C. fluctifraga and C. californiensis from the northern Gulf of California were strung together to form a master-chronology that covers the period from ad 1982 to 1999. A high positive correlation was found between standardized annual growth rates and summer sea-surface temperatures and river flow volume in the period 1988–99; and 63–76% of the variation in mean relative annual growth rates of Chione spp. is explained by temperature and river flow. Seven dead-collected specimens were cross-dated with the master-chronology permitting the reconstruction of the year of hatching and death for these shells. The incorporation of dead-collected specimens in the master-chronology improved the corre lation statistics slightly. Species-related growth differences were not significant, but geographic differences in growth rates occur: individuals at the Colorado River mouth grew more slowly when large amounts of fresh water reached the Gulf. This study demonstrates that even short-lived molluscs (average 6–10 years old) can be used to build a master-chronology of environmental and climatic history.
Use of scanning electron microscopy to investigate records of soil weathering preserved in lake sediment
Authors: Ewing Holly A. , Nater Edward A.
Published: February 2003

Reconstruction of soil weathering is one of the more difficult problems for palaeoecologists interested in landscape-scale environmental changes. Here we use scanning electron microscopy and energy dispersive x-ray analysis (SEM/EDS) to study the pitting of feldspars in soils and lake sediments at two sites in the Great Lakes region, USA. A semi-quantitative feldspar weathering index (FWI) allows description of the weathering status for large numbers of individual grains, and reveals differences among soil horizons and strata of lake sediment as well as between the two sites. Feldspars in upper soil horizons generally have greater FWI than those in lower horizons, but analyses also suggest considerable weathering in the soil C horizon at the site with more rapid water infiltration. At one site, the FWI of upper soil horizons and surface lake sediment are similar, implying that lake sediments have the potential to record changes in soil over time. However, differ ences between upper soil horizons and surface sediment at the other site highlight the need to examine more sites and more profiles within sites to better relate catchment and sediment characteristics. We interpret increases in the FWI over time within lake sediments as evidence of progressive weathering of soils and conclude that the sites had different histories of soil development. However, the complexities of sediment deposition in lakes and the paucity of information relating FWI to soil characteristics prevent straightforward reconstruction of soil development. Variability within each record appears tied to initial grain chemistry, depo sitional environment, changes in lake level and progressive degradation of grains. As more information relating micromorphology to soil characteristics becomes available, this technique should become a more useful complement to chemical studies of lake sediment.
Aeolian cliff-top deposits and buried soils in the White River Badlands, South Dakota, USA
Authors: Rawling J. Elmo , Fredlund Glen G. , Mahan Shannon
Published: February 2003

Aeolian deposits in the North American Great Plains are important sources of Holocene palaeo environmental records. Although there are extensive studies on loess and dune records in the region, little is known about records in aeolian cliff-top deposits. These are common on table (mesa) edges in the White River Badlands. These sediments typically have loam and sandy-loam textures with dominantly very fine sand, 0.5–1% organic carbon and 0.5–5% CaCO3. Some of these aeolian deposits are atypically coarse and contain granules and fine pebbles. Buried soils within these deposits are weakly developed with A-C and A-AC-C profiles. Beneath these are buried soils with varying degrees of pedogenic development formed in fluvial, aeolian or colluvial deposits. Thickness and number of buried soils vary. However, late-Holocene soils from several localities have ages of approximately 1300, 2500 and 3700 14C yrs BP. The 1300 14C yr BP soil is cumulic, with a thicker and lighter A horizon. Soils beneath the cliff-top deposits are early-Holocene (typically 7900 but as old as 10000 14C yrs BP) at higher elevation (|950 m) tables, and late-Holocene (2900 14C yrs BP) at lower (|830 m) tables. These age estimates are based on total organic matter 14C ages from the top 5 cm of buried soils, and agreement is good between an infrared stimulated luminescence age and bracketing 14C ages. Our studies show that cliff-top aeolian deposits have a history similar to that of other aeolian deposits on the Great Plains, and they are another source of palaeoenvironmental data.
Amiodarone Attenuates Fluoride‐induced Hyperkalemia in Vitro
Authors: Su Mark , Chu Jason , Howland Mary Ann , Nelson Lewis S. , Hoffman Robert S.
Published: February 2003

Poisoning by hydrofluoric acid or fluoride salts results in hypocalcemia, hypomagnesemia, and hyperkalemia with subsequent cardiac dysrhythmias. In previous studies, quinidine attenuated fluoride‐induced hyperkalemia in vitro, and enhanced survival in animals. Like quinidine, amiodarone is a potassium channel blocker, although amiodarone is more familiar to clinicians due to its recent inclusion in advanced cardiac life support (ACLS) protocols. Objectives: This in‐vitro study of human erythrocytes was designed to determine whether amiodarone could attenuate fluoride‐induced hyperkalemia. Methods: Six healthy volunteers each donated 60 mL of blood on three occasions. Each specimen was divided into 12 tubes, incubated at 37°C, and oxygenated with room air. An aqueous sodium fluoride (F−) solution was added to tubes 1–9. Incremental amounts of quinidine were added to tubes 1–4 (Q1–Q4) to attain calculated concentrations of 0.73 μg/mL, 1.45 μg/mL, 2.9 μg/mL, and 5.8 μg/mL, respectively. Incremental amounts of amiodarone were added to tubes 5–8 (A1–A4) to attain calculated concentrations of 0.38 μg/mL, 0.75 μg/mL, 1.5 μg/mL, and 3.0 μg/mL, respectively. Tubes 9–12 were controls for each of F−, amiodarone, quinidine alone, and no additive, respectively. Extracellular potassium concentration ([K+]) was followed, and an objective endpoint was defined as the rise in potassium concentration at 6 hours. Results: Fluoride produced a significant change in [K+] by 6 hours in all samples. Quinidine produced a J‐shaped curve in its ability to attenuate the rise in [K+], with only one concentration, Q3, demonstrating significance versus tube 9 (control). Amiodarone also demonstrated a J‐shaped dose–response effect, with statistical significance at A1, A2, and A3 versus tube 9 (control). There was no significant difference among the effective concentrations (Q3, A1, A2, and A3) of both drugs. Conclusions: In this in‐vitro model using human blood, amiodarone and quinidine both attenuated F−‐induced hyperkalemia. Further study is indicated to determine whether amiodarone enhances survival in F−‐poisoned animals.
Beta‐Human Chorionic Gonadotropin Levels and the Likelihood of Ectopic Pregnancy in Emergency Department Patients with Abdominal Pain or Vaginal Bleeding
Authors: Kohn Michael A. , Kerr Kristi , Malkevich David , O'Neil Nelda , Kerr M. James , Kaplan Beth C.
Published: February 2003

Strategies for diagnosing ectopic pregnancy that defer endovaginal ultrasound in women with suggestive symptoms and serum beta‐human chorionic gonadotropin (β‐hCG) levels less than 1,500 mIU/mL ignore the increased risk of ectopic pregnancy in these patients. Objective: To quantify this increased risk by establishing and comparing the β‐hCG distributions of symptomatic women with ectopic pregnancies, abnormal intrauterine pregnancies, and normal intrauterine pregnancies. Methods: The authors reviewed the records of a cohort of women who visited an urban emergency department (ED) during a 34‐month period with abdominal pain or vaginal bleeding and non‐zero quantitative β‐hCG levels. Explicit criteria were used to determine whether the pregnancy ultimately turned out to be intrauterine and normal, intrauterine and abnormal, or ectopic. Probability distributions were compared using frequency distributions, receiver operating characteristic (ROC) curves, and likelihood ratios. Results: Of 730 ED patients included in the analysis, 96 (13%) had ectopic pregnancies, 253 (35%) had abnormal intrauterine pregnancies, and 381 (52%) had normal intrauterine pregnancies. The β‐hCG distributions of patients with ectopic pregnancies and abnormal intrauterine pregnancies were similar and much lower than the β‐hCG distribution of patients with normal intrauterine pregnancies. A β‐hCG level less than 1,500 mIU/mL more than doubled the odds of ectopic pregnancy (likelihood ratio = 2.24). Of the 158 patients with β‐hCG below 1,500 mIU/mL, 40 (25%; 95% confidence interval [CI] = 19% to 32%) had ectopic pregnancies, and only 25 (16%; CI = 11% to 22%) had normal intrauterine pregnancies. Conclusions: In women with pain or bleeding and serum β‐hCG levels less than 1,500 mIU/mL, the risk of ectopic pregnancy is substantially increased, while the likelihood of normal intrauterine pregnancy is low.
The Effect of Hospital Occupancy on Emergency Department Length of Stay and Patient Disposition
Authors: Forster Alan J. , Stiell Ian , Wells George , Lee Alexander J. , Van Walraven Carl
Published: February 2003

Emergency department (ED) overcrowding is a common problem. Despite a widespread belief that low hospital bed availability contributes to ED overcrowding, there are few data demonstrating this effect. Objectives: To identify the effect of hospital occupancy on ED length of stay for admitted patients and patient disposition. Methods: This was an observational study design using administrative data at a 500‐bed acute care teaching hospital. All patients presenting to the ED between April 1993 and June 1999 were included in the study. The predictor variable was daily hospital occupancy. Outcome measures included daily ED length of stay for admitted patients, daily consultation rate, and daily admission rate. The models controlled for the average daily age of ED patients and the average daily “arrival density” index, which adjusts for patient volume and clustering of patient arrivals. Results: The average hospital occupancy was 89.7%. On average 155 patients visited the ED daily; 21% were referred to hospital physicians and 19% were admitted. The median ED length of stay for admitted patients was 5 hours 54 minutes (interquartile range 5 hr 12 min to 6 hr 42 min). Daily ED length of stay for admitted patients increased 18 minutes (95% CI = 12 to 24) when there was an absolute increase in occupancy of 10%. The ED length of stay appeared to increase extensively when hospital occupancy exceeded a threshold of 90%. Consultation and admission rates were not influenced by hospital occupancy. Conclusions: Increased hospital occupancy is strongly associated with ED length of stay for admitted patients. Increasing hospital bed availability might reduce ED overcrowding.
Etomidate for Rapid‐sequence Intubation in Young Children: Hemodynamic Effects and Adverse Events
Authors: Guldner Gregory , Schultz Jason , Sexton Perry , Fortner Corwyn , Richmond Mark
Published: February 2003

Objectives: Physicians commonly use etomidate for adult rapid‐sequence intubation (RSI), but the manufacturer does not recommend its use for children under 10 years of age due to a lack of data. The authors present their experience with etomidate for pediatric RSI in order to further develop its risk–benefit profile in this age group. Methods: Trained abstractors reviewed the medical records for all children under 10 years old who received etomidate for RSI between July 1996 and April 2001. Results: 105 children, with an average age of 3 (±2.9) years, received a median dose of 0.32 (±0.12) mg/kg of etomidate. The systolic blood pressure increased an average of 4 mm Hg (95% CI =−3.3 to 9.2); the diastolic blood pressure increased 7 mm Hg (95% CI =−3.1 to 11) within 10 minutes of receiving etomidate. The heart rate increased an average of 10 beats/min (95% CI = 4.0 to 17.4). Complications included three patients who vomited within 10 minutes of etomidate administration. There were no cases of documented myoclonus, status epilepticus, or new‐onset seizures. Thirty‐eight patients received corticosteroids during the hospital course, none for suspected adrenal insufficiency. Three patients died, all from severe brain injury. Conclusions: In children less than 10 years old, etomidate seems to produce minimal hemodynamic changes, and appears to have a low risk of clinically important adrenal insufficiency, myoclonus, and status epilepticus. The association between etomidate and emesis (observed in less than 3% of enrolled patients) remains unclear. For clinical situations in which minimal blood pressure changes during RSI are critical, etomidate appears to have a favorable risk–benefit profile for children under 10 years old.
Ventilatory Response during Dissociative Sedation in Children—A Pilot Study
Authors: Kim Grace , Green Steven M. , Denmark T. Kent , Krauss Baruch
Published: February 2003

Objectives: It is unclear whether ketamine induces subclinical respiratory depression when administered in dissociative doses intravenously (IV). The authors report a pilot study of capnography in emergency department (ED) pediatric patients receiving ketamine alone for procedural sedation, and describe serial measures of ventilatory response [end‐tidal carbon dioxide (EtCO2), respiratory rate, pulse oximetry]. Methods: The authors performed continuous capnography on a convenience sample of 20 ED pediatric patients who received ketamine 1.5 mg/kg IV for procedural sedation. Results: Continuous EtCO2 and pulse oximetry remained essentially unchanged following ketamine injection, and no EtCO2 levels > 47 mm Hg were noted at any point throughout sedation. Conclusions: No hypoventilation was observed in 20 ED pediatric patients receiving ketamine 1.5 mg/kg administered IV over 1 minute. The authors found no evidence of respiratory depressant properties for this dissociative agent.
Can Emergency Department Triage Nurses Appropriately Utilize the Ottawa Knee Rules to Order Radiographs?—An Implementation Trial
Authors: Kec Robert M. , Richman Peter B. , Szucs Paul A. , Mandell Mark , Eskin Barnet
Published: February 2003

Objective: To determine whether triage nurses can successfully interpret the Ottawa Knee Rule (OKR) and order knee radiographs according to the OKR. Methods: This was a prospective implementation trial of a clinical decision rule, set in a suburban, community emergency department (ED), evaluating a convenience sample of ED patients aged > 17 years with acute knee injuries. Patients were excluded for altered mental status, distracting injuries, and knee lacerations. Triage nurses and attending emergency physicians (EPs) were trained in appropriate use of the OKR. The triage nurses evaluated eligible patients and radiographs were ordered according to their interpretation of the OKR. EPs who were initially blinded to the triage assessments also evaluated the patients. EPs could add an x‐ray order if, according to their assessment of the OKR, one was indicated and a radiograph had not been ordered by the nurse. Nurses and EPs recorded their blinded assessments on standardized data collection instruments. Kappa values were calculated to assess interobserver agreement (IOA) between nurses and EPs; sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) were calculated as appropriate. Results: One hundred three patients were enrolled; 53% were female; 10 fractures were identified (9.7%). The IOAs between the nurses and EPs for each of the criteria were moderate to almost perfect: age—0.94; fibular head tenderness—0.4; isolated patellar tenderness—0.68; inability to bend knee to 90 degrees—0.73; inability to bear weight—0.76. The IOA was moderate (0.52) for the overall interpretation of the OKR by nurses and EPs. Sensitivity of nurse interpretation of the OKR for fracture was 70%, specificity 33%, NPV 91%, PPV 10%. Sensitivity of EP interpretation of the OKR for fracture was 100%, specificity 25%, NPV 100%, PPV 13%. Conclusions: Triage nurses showed fair to good ability to appropriately apply the OKR to pre‐order knee radiographs.
Incidence of Traumatic Lumbar Puncture
Authors: Shah Kaushal H. , Richard Kathleen M. , Nicholas Sarah , Edlow Jonathan A.
Published: February 2003

Objective: To determine the incidence of traumatic lumbar puncture (LP). Methods: A retrospective study was conducted at an urban, university tertiary care referral center with 50,000 annual emergency department (ED) visits. The study population included all patients who had cerebrospinal fluid (CSF) samples sent to the laboratory between August 15, 2000, and August 14, 2001. The numbers of red blood cells (RBCs) recorded in the first and last CSF tubes, the location where the LP was performed, and the discharge summary and the discharge diagnoses from the particular visit were obtained. All patients with intracranial pathology and CSF obtained via neurosurgical procedure or fluoroscopic guidance were excluded from the study group. Given no clear definition of traumatic LP in the literature, the incidence of traumatic LP was calculated using a cutoff of greater than 400 RBCs (visual threshold for bloody fluid) and 1,000 RBCs (arbitrary threshold selected by other authors) in CSF tube 1. Proportions were compared using chi‐square statistics. Results: Seven hundred eighty‐six CSF samples were recorded over one year. Twenty‐four samples were obtained from patients with intracranial pathology or were obtained via a neurosurgical procedure. Of the remaining 762 CSF samples in the study population, 119 (15.6%) were traumatic using a cutoff of 400 RBCs, and 80 (10.5%) were traumatic, using a cutoff of 1,000 RBCs in tube 1. Five hundred three LPs were done in the ED and 259 were attributed to all other locations in the hospital. Using a cutoff of 400 RBCs, the incidence of traumatic LP in the ED was 13.3%, compared with 20% in the rest of the hospital (p < 0.025). Similarly, using a cutoff of 1,000 RBCs, the incidence of traumatic LP in the ED was 8.9%, compared with 13.5% in the rest of the hospital (p = 0.1). The incidence of “champagne taps” (defined as zero RBCs in the first and last tubes) in the ED was 34.4%, compared with 24.3% in the rest of the hospital (p < 0.01). Conclusions: The incidence of traumatic lumbar puncture is approximately 15% using a cutoff of 400 RBCs and 10% using a cutoff of 1,000 RBCs. In this study, the rate of traumatic lumbar puncture was significantly less (with a cutoff of 400 RBCs) and the rate of champagne tap was significantly greater for LPs done in the ED compared with the rest of the hospital.
Emergency Medicine Leadership in Industry‐sponsored Clinical Trials
Authors: Newgard Craig D. , Kim Sunghye , Camargo Carlos A.
Published: February 2003

Objective:To identify and characterize emergency medicine (EM) researchers who, since 1990, have served on a steering committee (SC) or as overall principal investigator (PI) of an industry‐sponsored, multicenter clinical trial involving a pharmaceutical or device.Methods:North American EM research directors (RDs) and other prominent EM investigators (for those hospitals without a RD) were identified from eight sources, including the Society for Academic Emergency Medicine RD Interest Group and the Multicenter Airway Research Collaboration (MARC) database. The identified investigators were sent a screening survey requesting information regarding industry‐sponsored clinical research at their site. The individual EM investigators identified by this screening survey were then interviewed by telephone (validation survey) to further explore their leadership experience in industry‐sponsored clinical trials.Results:Of 153 identified RDs and prominent EM researchers, 138 responded to the screening survey (90% response rate). Eighty‐five EM investigators reportedly had served on a SC or as overall PI for an industry‐sponsored clinical trial. Of these 85 North American EM investigators, 77 were available for a structured telephone interview (91% response rate). Although 41 (53%) of the investigators confirmed their leadership role, 36 (47%) had not served in either role. Among the 41 confirmed investigators, 19 (25%) had served as a SC member, 10 (13%) had served as overall PI, and 12 (16%) had experience in both roles. Individual responses provided suggestions for pursuing such leadership positions.Conclusions:These data suggest the opportunity to expand EM leadership in industry‐sponsored clinical trials and demonstrate the need for validation of reports obtained by a departmental research contact. The suggestions from EM researchers who have attained these leadership roles may provide strategies for investigators interested in pursuing these positions.
Predictors of Success in Emergency Medicine Ultrasound Education
Authors: Costantino Thomas G. , Satz Wayne A. , Stahmer Sarah A. , Dean Anthony J.
Published: February 2003

Objectives: To compare emergency medicine resident performance on an ultrasound‐oriented, American Board of Emergency Medicine–styled written examination with the following variables in resident education: number of ultrasound scans performed, presence of a formal, structured ultrasound rotation, presence of a mandatory ultrasound rotation, number of hours of didactic ultrasound education, and percentage of ultrasound education taught by emergency physicians. Methods: This was a prospective cohort study involving 14 residency programs. A 60‐question multiple‐choice test was completed by individual residents and returned for scoring. Results: 262 residents completed the study. Average score was 39.1/60 ± 6.5 (65%). Scores improved as residency year increased (year 1: 36.6, year 2: 39.3, year 3: 42.6) (p < 0.005). Scores improved as number of scans performed increased from 34.3 (57%) for those residents who had performed 0–10 scans to 45.4 (76%) for those with >150 scans (p < 0.005). The presence of an ultrasound rotation at an emergency medicine residency program also produced a statistically significant increase in test score (OR 1.82; 95% CI = 1.29 to 2.55). Residents at programs spending the least time (6 to 15 hours) on didactic education throughout the residency predicted examination failure (OR 0.60; 95% CI = 0.39 to 0.93). Increasing the amount of resident ultrasound teaching by emergency physicians improved the score, but this did not reach significance (p = 0.357). Conclusions: Improved resident performance on an ultrasound written examination was associated with increasing resident year, number of scans performed, and the presence of an ultrasound rotation at the residency program. Increasing the number of didactic hours spent on ultrasound each year beyond 15 hours showed no improvement in resident performance.
Dietary Composition in Restoring Reproductive and Metabolic Physiology in Overweight Women with Polycystic Ovary Syndrome
Authors: Moran L. J. , Noakes M. , Clifton P. M. , Tomlinson L. , Norman R. J.
Published: February 2003

Overweight women with polycystic ovary syndrome (PCOS) were randomized to a high protein (HP; 40% carbohydrate and 30% protein; n = 14) or a low protein (LP; 55% carbohydrate and 15% protein) diet (n = 14). The intervention consisted of 12 wk of energy restriction (∼6000 kJ/d), followed by 4 wk of weight maintenance. Pregnancies (two HP and one LP); improvements in menstrual cyclicity, lipid profile, and insulin resistance (as measured by the homeostasis model); and decreases in weight (7.5%) and abdominal fat (12.5%) occurred independently of diet composition. Improvements in menstrual cyclicity were associated with greater decreases in insulin resistance and fasting insulin (P = 0.011). On the LP diet, high density lipoprotein cholesterol decreased 10% during energy restriction (P = 0.008), and the free androgen index increased 44% in weight maintenance stages (P = 0.027). Weight loss leads to improvements in cardiovascular and reproductive parameters potentially mediated by improvements in surrogate measures of insulin resistance. An HP weight loss diet may result in minor differential endocrine and metabolic improvements.
Multiple Indexes of Lipid Availability Are Independently Related to Whole Body Insulin Action in Healthy Humans
Authors: Kriketos Adamandia D. , Furler Stuart M. , Gan Seng Khee , Poynten Ann M. , Chisholm Donald J. , Campbell Lesley V.
Published: February 2003

An increase in muscle lipid content has been postulated to relate closely to the evolution of insulin resistance. We aimed to test whether the multiple indexes of lipid supply within man [namely, circulating triglycerides, skeletal muscle triglycerides (SMT), total and central fat mass, and circulating leptin] were independent predictors of insulin resistance, or whether triglycerides from different sources are additive in their influence on whole body insulin sensitivity. Whole body insulin sensitivity, body composition, and SMT content were determined in 49 sedentary, nondiabetic males (age, 20–74 yr; body mass index, 20–38 kg/m2). Insulin sensitivity was inversely associated with central abdominal fat (r2 = 0.38; P < 0.0001), total body fat (r2 = 0.21; P = 0.0003), SMT content (r2 = 0.16; P = 0.005), and fasting triglycerides (r2 = 0.24; P = 0.0003), nonesterified free fatty acid (r2 = 0.19; P = 0.002), and leptin (r2 = 0.35; P < 0.0001) levels. However, only central abdominal fat was significantly related to SMT content (r2 = 0.10; P = 0.03). SMT content, circulating triglycerides, and measurements of total or central adiposity were independent predictors of whole body insulin sensitivity.
Ovarian Steroids Differentially Modulate the Gene Expression of Gonadotropin-Releasing Hormone Neuronal Subtypes in the Ovariectomized Cynomolgus Monkey
Authors: Krajewski Sally J. , Abel Ty W. , Voytko Mary Lou , Rance Naomi E.
Published: February 2003

In the present study, we compared the morphology and distribution of neurons expressing GnRH gene transcripts in the hypothalamus and forebrain of the cynomolgus monkey to that of the human. As in the human, three subtypes of GnRH neurons were identified. Type I GnRH neurons were small, oval cells with high levels of gene expression and were located within the basal hypothalamus. Type II GnRH neurons were small and sparsely labeled and were widely scattered in the hypothalamus, midline nuclei of the thalamus, and extended amygdala. Type III neurons displayed magnocellular morphology and intermediate labeling intensity and were located in the nucleus basalis of Meynert, caudate, and amygdala. In a second experiment, we determined the effect of estrogen or estrogen plus progesterone on the gene expression of GnRH neurons in the brains of young, ovariectomized cynomolgus monkeys. We report that hormone treatment resulted in a significant decrease in GnRH mRNA in type I neurons within the basal hypothalamus of ovariectomized monkeys. In contrast, there was no effect of hormone treatment on the gene expression of type III GnRH neurons in the nucleus basalis of Meynert. The present findings provide evidence that the increase in gene expression of type I GnRH neurons in postmenopausal women is secondary to the ovarian failure of menopause. The differential responses of type I and III GnRH neurons to hormone treatment provide additional evidence that distinct subpopulations of neurons expressing GnRH mRNA exist in the primate hypothalamus.
The organization of adherens junctions and desmosomes at the cardiac intercalated disc is independent of gap junctions
Authors: Gutstein David E. , Liu Fang-yu , Meyers Marian B. , Choo Andrew , Fishman Glenn I.
Published: February 2003

Adherens junctions and desmosomes are responsible for mechanically coupling myocytes in the heart and are found closely apposed to gap junction plaques at the intercalated discs of cardiomyocytes. It is not known whether loss of cardiac gap junctions, such as described in cardiac disease states, may influence the expression patterns of other intercalated disc-associated proteins. We investigated whether the major cardiac gap junction protein connexin43 (Cx43) may be responsible for regulating adherens junctions,desmosomes and their associated catenins, in terms of abundance and localization at the intercalated discs of cardiomyocytes. In order to study the effect of loss of cardiac gap junctions on the intercalated disc-associated proteins, we used a combination of immunoblotting,immunofluorescence with confocal microscopy and electron microscopy to evaluate heart tissue from mice with cardiac-specific conditional knockout of Cx43. We found that the cardiac adherens junctions, desmosomes and their associated catenins, as well as vinculin and ZO-1, maintain their normal abundance, structural appearance and localization in the absence of Cx43. We conclude from these data that Cx43 is not required for the organization of the cell adhesion junctions and their associated catenins at the intercalated disc in the adult cardiac myocyte.
Remodeling of endosomes during lysosome biogenesis involves `kiss and run' fusion events regulated by rab5
Authors: Duclos Sophie , Corsini Rachel , Desjardins Michel
Published: February 2003

The small GTPase rab5 has been shown to play key roles in the function of both endocytic and phagocytic organelles. Although these organelles share several additional common features, different processes have been proposed to explain their biogenesis. In the present study, we provide evidence that lysosome biogenesis involves mechanisms similar to those previously described for the formation of phagolysosomes. Transient interactions (`kiss and run')between endocytic organelles are shown to occur during lysosome biogenesis. These interactions are regulated initially by the GTPase activity of rab5, as demonstrated by the loss of size-selective fusion between endosomes in cells expressing a GTPase-deficient mutant of rab5. Endocytic compartments in these cells sequentially display properties of early and late endosomes. However,the formation of lysosomes and the sorting of endocytic solute materials to small electron dense vacuoles are not affected by the rab5 mutation. Together,our results indicate that endosome maturation occurs during the early part of lysosome biogenesis. This process involves transient fusion events regulated,in part, by the small GTPase rab5.
Real-time analysis of clathrin-mediated endocytosis during cell migration
Authors: Rappoport Joshua Z. , Simon Sanford M.
Published: February 2003

Simultaneous dual-color total-internal-reflection fluorescence microscopy(TIR-FM) was performed to analyze the internalization and distribution of markers for clathrin-mediated endocytosis (clathrin, dynamin1, dynamin2 and transferrin) in migrating cells. In MDCK cells, which endogenously express dynamin2, the dynamin2-EGFP fluorescence demonstrated identical spatial and temporal behavior as clathrin both prior to and during internalization. By contrast, in the same cells, the neuronal dynamin1 only localized with clathrin just prior to endocytosis. In migrating cells, each endocytic marker was polarized towards the leading edge, away from the lagging edge. These observations suggest a re-evaluation of the functional differences between dynamin1 and dynamin2, and of the role of clathrin-mediated endocytosis in cell migration.
Membrane insertion of the chloroplast outer envelope protein, Toc34:constrains for insertion and topology
Authors: Qbadou Soumya , Tien Roselynn , Soll Jürgen , Schleiff Enrico
Published: February 2003

The insertion of the outer envelope protein Toc34 from chloroplasts was studied. Toc34 was chosen as a model protein because it contains one predicted transmembrane helix at the C-terminus and a large hydrophilic N-terminal located GTPase domain, which is exposed to the cytosol. Unlike proteins located in internal chloroplast compartments, Toc34 neither contains a cleavable presequence nor uses the general import pathway. The protein can insert into the outer envelope of chloroplasts but not into the outer membrane of mitochondria. Using protein-free liposomes we showed that Toc34 is able to insert directly into the lipid bilayer. This insertion is stimulated by GTP and the presence of nonbilayer lipids, but is independent of the presence or absence of charged lipids. The topology of the protein inserted into protein-free liposomes was not exclusively directed by the positive-inside rule but by the size of the hydrophilic domain.
Expression of the nidogen-binding site of the laminin γ1 chain disturbs basement membrane formation and maintenance in F9 embryoid bodies
Authors: Tunggal Judith , Wartenberg Maria , Paulsson Mats , Smyth Neil
Published: February 2003

Basement membranes contain two major molecular networks consisting of laminin and collagen IV. Previous antibody perturbation experiments suggest that the interaction between laminin and nidogen-1 is necessary for proper basement membrane formation and epithelial development, whereas results from gene ablation experiments in mice show that both basement membranes and general development are grossly normal in the absence of nidogen-1. To refine the perturbation approach, we produced F9-teratocarcinoma-cell-derived embryoid bodies in the presence of recombinantly expressed nidogen-binding sites localized within the γ1III3-5 laminin fragment. We found basement membranes were disrupted in γ1III3-5-expressing embryoid bodies. As a measurement of basement membrane function, we tested permeability and detected drastically increased diffusion rates in correlation with basement membrane disruption. Furthermore, TROMA-1 localization in embryoid bodies expressing the nidogen-binding site was altered, suggesting separation of epithelium-specific gene expression from the formation of the actual epithelium when occurring in the absence of an organized basement membrane.
Nonerythroid αII spectrin is required for recruitment of FANCA and XPF to nuclear foci induced by DNA interstrand cross-links
Authors: Sridharan Deepa , Brown Monique , Lambert W. Clark , McMahon Laura W. , Lambert Muriel W.
Published: February 2003

The events responsible for repair of DNA interstrand cross-links in mammalian cells, the proteins involved and their interactions with each other are poorly understood. The present study demonstrates that the structural protein nonerythroid α spectrin (αSpIIΣ*), present in normal human cell nuclei, plays an important role in repair of DNA interstrand cross-links. These results show that αSpIIΣ* relocalizes to nuclear foci after damage of normal human cells with the DNA interstrand cross-linking agent 8-methoxypsoralen plus ultraviolet A (UVA) light and that FANCA and the known DNA repair protein XPF localize to the same nuclear foci. That αSpIIΣ* is essential for this re-localization is demonstrated by the finding that in cells from patients with Fanconi anemia complementation group A (FA-A), which have decreased ability to repair DNA interstrand cross-links and decreased levels of αSpIIΣ*, there is a significant reduction in formation of damage-induced XPF as well asαSpIIΣ* nuclear foci, even though levels of XPF are normal in these cells. In corrected FA-A cells, in which levels of αSpIIΣ*are restored to normal, numbers of damage-induced nuclear foci are also returned to normal. Co-immunoprecipitation studies show thatαSpIIΣ*, FANCA and XPF co-immunoprecipitate with each other from normal human nuclear proteins. These results demonstrate thatαSpIIΣ*, FANCA and XPF interact with each other in the nucleus and indicate that there is a close functional relationship between these proteins. These studies suggest that an important role for αSpIIΣ* in the nucleus is to act as a scaffold, aiding in recruitment and alignment of repair proteins at sites of damage.
Drosophila dd4mutants reveal that γTuRC is required to maintain juxtaposed half spindles in spermatocytes
Authors: Barbosa Vitor , Gatt Melanie , Rebollo Elena , Gonzalez Cayetano , Glover David M.
Published: February 2003

The weak spindle integrity checkpoint in Drosophila spermatocytes has revealed a novel function of the γ-tubulin ring complex(γTuRC) in maintaining spindle bipolarity throughout meiosis. Bipolar and bi-astral spindles could form in Drosophila mutants for dd4, the gene encoding the 91 kDa subunit of γTuRC. However,these spindles collapsed around metaphase and began to elongate as if attempting anaphase B. The microtubules of the collapsing spindle folded back on themselves, their putative plus ends forming the focused apexes of biconical figures. Cells with such spindles were unable to undergo cytokinesis. A second type of spindle, monopolar hemi-spindles, also formed as a result of either spindle collapse at an earlier stage or failure of centrosome separation. Multiple centrosome-like bodies at the foci of hemi-spindles nucleated robust asters of microtubules in the absence of detectable γ-tubulin. Time-lapse imaging revealed these to be intermediates that developed into cones, structures that also had putative plus ends of microtubules focused at their tips. Unlike biconical figures,however, cones seemed to contain a central spindle-like structure at their apexes and undergo cytokinesis. We conclude that spermatocytes do not need astral microtubules nucleated by opposite poles to intersect in order to form a central spindle and a cleavage furrow.
Preliminary Evidence for a Sulphur Cycle in Movile Cave, Romania
Authors: Rohwerder T. , Sand W. , Lascu C.
Published: February 2003

In order to investigate the food chain and energy balance of the chemolithoautotrophically‐based ecosystem of the sulphur spring in Movile Cave as a model system for extraterrestrial life, a first sampling campaign was done. Microbial diversity and activity were analysed by MPN‐enumeration methods and microcalorimetry, respectively. In addition, a speciation of the inorganic sulphur compounds by HPLC and IC techniques was performed. Metabolic activities were predominantly connected with thick microbial mats floating on the water surface of the cave. These mats showed an aerobic heat evolution of about 1200 μW/g and contained about 500 μmol/g elemental sulphur. In contrast, other samples collected from cave water, sediment and rock exhibited only activities of maximal 40 to 60 μW/g and contained only up to 2.5 μmol/g elemental sulphur. As the main primary producers aerobic and facultatively anaerobic sulphur oxidisers were identified at high numbers, occasionally exceeding 107 CFU/g. Methylotrophic bacteria were present in all samples at up to 106 CFU/g, indicating the important role of C1 metabolism for the cave ecosystem. Although reduced sulphur species were biologically oxidised to sulphuric acid, the pH values of the samples ranged from 6.5 to 8.2 due to the high buffering capacity of the cave walls, which consisted mainly of limestone. Surprisingly, not only neutrophilic but also extremely acidophilic bacteria were detected. Sulphate reducers were present in both aerobic and anaerobic zones. The data presented suggest a close interdependence of sulphur oxidation and reduction as well as carbon dioxide and other C1 compound metabolism in the most biologically active zone of the cave ecosystem, i.e. the floating microbial mats.
Characterisation of Archaea in Soils by Polar Lipid Analysis
Authors: Gattinger A. , Günthner A. , Schloter M. , Munch J.C.
Published: February 2003

While phospholipid fatty acid (PLFA) profiling is a well‐established method used for the determination of bacterial and eukaryotic organisms in soil ecology, phospholipid etherlipid (PLEL) analyses for the characterisation of Archaea is a rather new approach. Analyses of PLEL derived isoprenoid side chains by GC/MS provided a broad picture of the archaeal community in a mixed soil extract, as lipids previously identified in isolates belonging to the kingdoms Eury‐ and Crenarchaeota were covered. Furthermore, ether‐linked isoprenoid hydrocarbons, which have not been detected in archaeal isolates and monomethyl‐branched alkanes which have only been found in hyperthermophilic bacteria, were detected in these soil extracts. Monomethyl‐branched alkanes were the most dominant ones and accounted for 43.4% of the total identified ether‐linked hydrocarbons, followed by straight chain (unbranched) and isoprenoid hydrocarbons, which accounted for 34.6 and 15.5%, respectively.
Purification and Characterisation of the Enantiospecific Dioxygenases from Delftia acidovorans MC1 Initiating the Degradation of Phenoxypropionate and Phenoxyacetate Herbicides
Authors: Westendorf A. , Müller R. H. , Babel W.
Published: February 2003

After cultivation on (R,S)‐2‐(2,4‐dichlorophenoxy)propionate, two α‐ketoglutarate‐dependent dioxygenases were isolated and purified from Delftia acidovorans MC1, catalysing the cleavage of the ether bond of various phenoxyalkanoate herbicides. One of these enzymes showed high specificity for the cleavage of the R‐enantiomer of substituted phenoxypropionate derivatives: the Km values were 55 μM and 30 μM, the kcat values 55 min–1 and 34 min–1 with (R)‐2‐(2,4‐dichlorophenoxy)propionate [(R)‐2,4‐DP] and (R)‐2‐(4‐chloro‐2‐methylphenoxy)propionate, respectively. The other enzyme predominantly utilised the S‐enantiomers with Km values of 49 μM and 22 μM, and kcat values of 50 min–1 and 46 min–1 with (S)‐2‐(2,4‐dichlorophenoxy)propionate [(S)‐2,4‐DP] and (S)‐2‐(4‐chloro‐2‐methylphenoxy)propionate, respectively. In addition, it cleaved phenoxyacetate herbicides (i.e. 2,4‐dichlorophenoxyacetate: Km = 123 μM, kcat = 36 min–1) with significant activity. As the second substrate, only α‐ketoglutarate served as an oxygen acceptor for both enzymes. The enzymes were characterised by excess substrate inhibition kinetics with apparent Ki values of 3 mM with (R)‐2,4‐DP and 1.5 mM with (S)‐2,4‐DP. The reaction was strictly dependent on the presence of Fe2+ and ascorbate; other divalent cations showed inhibitory effects to different extents. Activity was completely extinguished within 2 min in the presence of 100 μM diethylpyrocarbonate (DEPC).
Stabilization of Semiconducting Polymers with Silsesquioxane
Authors: Xiao S. , Nguyen M. , Gong X. , Cao Y. , Wu H. , Moses D. , Heeger A.J.
Published: February 2003

Polyhedral oligomeric silsesquioxanes (POSS) anchored to poly(2‐methoxy‐5‐(2‐ethylhexyloxy)‐1.4‐phenylenevinylene) (MEH‐PPV) (MEH‐PPV–POSS), and to poly(9,9‐dihexylfluorenyl‐2,7‐diyl) (PFO) (PFO–POSS) were synthesized. Compared with the corresponding parent polymers, MEH‐PPV and PFO, MEH‐PPV–POSS and PFO–POSS have better thermal stability. MEH‐PPV–POSS and MEH‐PPV have identical absorption and photoluminescent (PL) spectra, both in solution and as thin films. They also have identical electroluminescent (EL) spectra. Devices made from MEH‐PPV–POSS exhibit higher brightness (1320 cd m–2 at 3.5 V) and higher external quantum efficiency (ηext = 2.2 % photons per electron) compared to MEH‐PPV (230 cd m–2 at 3.5 V and ηext = 1.5 % ph el–1). Compared with PFO in the same device configuration, PFO–POSS has improved blue EL emission and higher ηext.