bluuebunny/crossref_metadata_2025 huggingface dataset:
Cascading effects of variation in plant vigour on the relative performance of insect herbivores and their parasitoids
Authors: Teder Tiit , Tammaru Toomas
Published: March 2003

Abstract1. Consequences of variation in food plant quality were estimated for a system consisting of two monophagous noctuid herbivores and three ichneumonid parasitoids.

2. In a natural population, pupal weights of the herbivores in this system,Nonagria typhaeandArchanara sparganii, were found to be highly variable. Pupal weights increased strongly and consistently with the increase in the vigour of the host plant,Typha latifolia, providing support for the plant vigour hypothesis. Correspondingly, as the moths do not feed as adults, a strong, positive correlation between host vigour and fecundity of the herbivores would be expected.

3. There were strong and positive relationships between adult body sizes of the parasitoids and the sizes of their lepidopteran hosts. Moreover, a direct, positive link between plant quality and parasitoid size was documented.

4. For all three parasitoids, cascading effects of plant quality on body size were weaker than for the herbivores. Differences in the importance of adult feeding and oviposition behaviour suggest that dependence of fitness on body size is also weaker in the parasitoids than in the moths. It is therefore concluded that the numerical response of the herbivore population to a change in plant quality should exceed the corresponding response in the parasitoids.

5. The results of this work imply that variation in plant variables may affect performance of different trophic levels to a different extent. It is suggested that the importance of adult feeding for the reproductive success (capital vs. income breeding strategies) in both herbivores and parasitoids is an essential aspect to consider when predicting responses of such a system to changes in plant quality.
Experience‐based learning and its relevance to social work practice
Authors: Gray Mel , Gibbons Jill
Published: March 2003

The paper begins with a brief description of the experience‐based learning model developed by a group of social work educators at the University of Newcastle, in New South Wales. The Bachelor of Social Work (BSW) degree was introduced in 1991 and its first graduates entered the workforce in 1995. As well as outlining the theoretical underpinnings and core features of the model, the paper reports on a survey of graduates which examined their perceptions of the effectiveness of experience‐based learning in preparing them for social work practice. It ends with a brief discussion of the difficulties of staff and students in adapting to this model.
A randomized, controlled trial to study the effect of exercise consultation on the promotion of physical activity in people with Type 2 diabetes: a pilot study
Authors: Kirk A. F. , Higgins L. A. , Hughes A. R. , Fisher B. M. , Mutrie N. , Hillis S. , MacIntyre P. D.
Published: March 2003

Aim  To evaluate the effect of exercise consultation on promotion of physical activity in people with Type 2 diabetes.

Methods  Twenty‐six sedentary people with Type 2 diabetes were randomly assigned to receive an exercise consultation and standard exercise information (experimental) or standard exercise information alone (control). Exercise consultation is a one‐to‐one discussion, based on the transtheoretical model, designed to educate, strengthen motivation and develop realistic strategies to promote physical activity. Changes from baseline at five weeks were assessed in (a) stage of exercise behaviour (b) physical activity levels (7‐day recall questionnaire and an accelerometer) (c) quality of life (SF‐36 Health Survey and 22‐Item Well‐Being Questionnaire).

Results  82% (9/11) of participants receiving a consultation increased their stage of exercise behaviour compared to 33% (4/12) of controls (χ2 = 5.4, P= 0.02). Physical activity counts/week increased by 4% (1636 067/1696 191) in the experimental group and decreased by 9% (1560 960/1725 510) in controls. A significant difference was recorded for the change in activity counts per week from baseline to follow‐up between the experimental and control group (98% CI = 60 673–710 827). The number of participants taking part in sport or leisure activity increased by 55% (6/11) in the experimental group and decreased by 6% (1/12) in controls. Positive changes were evident in the experimental group, compared to controls, in both quality of life questionnaires.

Conclusion  Exercise consultation is more effective in stimulating exercise behaviour change in the short term than a standard exercise leaflet.

Diabet. Med. 18, 877–882 (2001)
What is the prevalence of visual impairment in the general and diabetic populations: are there ethnic and gender differences?
Authors: Hayward L. M. , Burden M. L. , Burden A. C. , Blackledge H. , Raymond N. T. , Botha J. L. , Karwatowski W. S. S. , Duke T. , Chang Y. F.
Published: March 2003

Aims To estimate the prevalence of blindness and partial sight in the general and diabetic populations and to measure the impact of ethnicity and gender on these rates.

Methods Data on visual impairment in the population to be studied was obtained from the Royal Leicestershire Rutland and Wycliffe Society for the Blind (RLRWSB). Using the validated technique of capture‐mark‐recapture (CMR), a census day was set and data from four sources collected: hospital admissions data, GP returns, wards, and mass media. Computer cross‐linkage to Leicestershire Health Authority data ensured patients were alive and resident in Leicestershire at the census date. Estimates of diabetes, ethnicity and gender prevalence were calculated using the 1991 census.

Results CMR calculations revealed that there was under ascertainment of visual impairment in the RLRWSB data. The CMR calculations with direct age standardization estimate the prevalence of blindness and partial sight in the general and diabetic populations to be 51.8/10 000 (CI 50.6–53.0) and 148.8/10 000 (CI 122.1–175.5), respectively. In the diabetic population there was a higher proportion of visually impaired females than males (P < 0.05), with no overall ethnic differences; however, rates were lower than expected in female Indo‐Asians. In the general population there was a higher proportion of visually impaired Indo‐Asian people (P < 0.01).

Conclusions Our study has shown the prevalence of visual impairment in both the general and diabetic populations and has demonstrated both ethnic and gender differences. CMR allows the calculation of prevalence of blindness and partial sight from existing data. When comparing the prevalence of visual impairment, whether from diabetes or other causes, it is important to know the gender and ethnicity of the ‘at risk’ population, as well as the rates in the background population.
Protein kinase C and the development of diabetic vascular complications
Authors: Way K. J. , Katai N. , King G. L.
Published: March 2003

Hyperglycemic control in diabetes is key to preventing the development and progression of vascular complications such as retinopathy, nephropathy and neuropathy. Increased activation of the diacylglycerol (DAG)‐protein kinase C (PKC) signal transduction pathway has been identified in vascular tissues from diabetic animals, and in vascular cells exposed to elevated glucose. Vascular abnormalities associated with glucose‐induced PKC activation leading to increased synthesis of DAG include altered vascular blood flow, extracellular matrix deposition, basement membrane thickening, increased permeability and neovascularization. Preferential activation of the PKCβ isoform by elevated glucose is reported to occur in a variety of vascular tissues. This has lead to the development of LY333531, a PKCβ isoform specific inhibitor, which has shown potential in animal models to be an orally effective and nontoxic therapy able to produce significant improvements in diabetic retinopathy, nephropathy, neuropathy and cardiac dysfunction. Additionally, the antioxidant vitamin E has been identified as an inhibitor of the DAG‐PKC pathway, and shows promise in reducing vascular complications in animal models of diabetes. Given the overwhelming evidence indicating a role for PKC activation in contributing to the development of diabetic vascular complications, pharmacological therapies that can modulate this pathway, particularly with PKC isoform selectivity, show great promise for treatment of vascular complications, even in the presence of hyperglycemia.

Diabet. Med. 18, 945–959 (2001)
What can we see with the endoscope? Present status and future perspectives
Authors: Tajiri Hisao , Matsuda Koji , Fujisaki Junko
Published: March 2003

The present status and future perspectives in new technologies of image processing and analysis, infrared ray endoscopy and autofluorescence endoscopy for gastrointestinal cancer are presented in this paper. Spectroscopic measurements using an endoscopic spectroscopic system are useful for distinguishing between benign and malignant gastric mucosal lesions, and the histological classification of early gastric cancer is possible on the basis of the spectroscopic characteristics. It is expected that adaptive hemoglobin index color enhancement would be useful for the qualitative diagnosis of early gastric cancer and for detecting specialized columnar epithelium in Barrett’s esophagus in combination with magnifying endoscopy. Our preliminary experience suggess that magnifying endoscopy with a narrow‐band imaging system could predict the histological characteristics of gastric cancerous lesions with high accuracy. Recent studies revealed that infrared ray electronic endoscopy is very useful for diagnosing the depth of invasion in early gastric cancer. In addition, it is evident that specific antibodies tagged with the indocyanine green derivative can label cancer cells and can generate a fluorescent signal strong enough to detect small cancers using an infrared fluorescence endoscope. The future development and evaluation of autofluorescence endoscopy are discussed, and we propose a modification to the system, including the excitation lights.
Short‐form HLA‐DP typing with 48 primer mixes using the polymerase chain reaction and sequence‐specific primers
Authors: Davidson J. A. , Poulton K. V.
Published: March 2003

We have developed a short‐form SSP‐based HLA‐DP typing system for routine use adapted from a comprehensive HLA‐DP typing method described by Gilchrist et al. (1998). Our short‐form system detects 93 alleles, including the 18 most common HLA‐DPB1 alleles and eight HLA‐DPA1 alleles. The primer mixes described were tested using the PCR‐SSP Manager (Bunce et al., 1998) database to confirm the specificity of selected primers, and to detect potentially ambiguous amplifications. This short‐form HLA‐DP typing system was validated using 50 fully typed samples obtained through the UCLA International DNA Exchange. All samples gave 100% concordance with the consensus type. Our laboratory routinely uses a PCR‐SSP based system of 48 primer mixes for HLA‐DRB and HLA‐DQB typing. The advantage of the short‐form HLA‐DP typing system described here is that the additional 48 HLA‐DP primer mixes required can be included on the second half of a 96‐well format tray. This method now enables a full HLA class II typing at the level of allele group resolution in 21/2 h.
Effects of the flavonoid baicalin and its metabolite baicalein on androgen receptor expression, cell cycle progression and apoptosis of prostate cancer cell lines
Authors: Chen S. , Ruan Q. , Bedner E. , Deptala A. , Wang X. , Hsieh T.C. , Traganos F. , Darzynkiewicz Z.
Published: March 2003

Recent studies on the Chinese herbal medicine PC SPES showed biological activities against prostate cancer in vitro, in vivo and in patients with advanced stages of the disease. In investigating its mode of action, we have isolated a few of the active compounds. Among them, baicalin was the most abundant (about 6%) in the ethanol extract of PC SPES, as determined by HPLC. Baicalin is known to be converted in vivo to baicalein by the cleavage of the glycoside moiety. Therefore, it is useful to compare their activities in vitro. The effects of baicalin and baicalein were studied in androgen‐positive and ‐negative human prostate cancer lines LNCaP and JCA‐1, respectively. Inhibition of cell growth by 50% (ED50) in LNCaP cells was seen at concentrations of 60.8 ± 3.2 and 29.8 ± 2.2 µm baicalin and baicalein, respectively. More potent growth inhibitory effects were observed in androgen‐negative JCA‐1 cells, for which the ED50 values for baicalin and baicalein were 46.8 ± 0.7 and 17.7 ± 3.4, respectively. Thus, it appears that cell growth inhibition by these flavonoids is independent of androgen receptor status. Both agents (1) caused an apparent accumulation of cells in G1 at the ED50 concentration, (2) induced apoptosis at higher concentrations, and (3) decreased expression of the androgen receptor in LNCaP cells.
How valuable is a lumbar puncture in the management of patients with suspected subarachnoid haemorrhage?
Authors: Foot Carole , Staib Andrew
Published: March 2003

Objective:

The aim of the study was to determine the range of cerebrospinal fluid findings associated with emergency department disposition and treatment of patients with headache suspicious of subarachnoid haemorrhage but a negative or equivocal computed tomoraphy head scan, in particular the role of xanthochromic index.

Methods:

A retrospective review of medical records of 196 adult patients who underwent cerebrospinal fluid examination for red cell count and xanthochromia for suspected subarachnoid haemorrhage but had a normal or equivocal computed tomography scan.

Results:

Included in the study were 196 patients. Only one patient out of 189 with a negative computed tomography scan was found to have a subarachnoid haemorrhage caused by a ruptured aneurysm (0.5%; 95% confidence intervals 0–2.9%). Three other patients were diagnosed with benign subarachnoid haemorrhage. Ninety‐one patients were stratified into the lowest possible risk group for subarachnoid haemorrhage and discharged home from the emergency department. All patients with equivocal computed tomography head scans and a positive xanthochromic index were admitted for cerebral angiography. In many cases, cerebrospinal fluid findings did not appear to influence clinical decision‐making.

Conclusions:

In the study institution, cerebrospinal fluid results appeared to have a variable influence on clinical decision‐making for patients with suspected subarachnoid haemorrhage and a non‐diagnostic computed tomography head scan. Of particular concern is the lack of validation of the tests used in this investigative approach, the frequency of patients having a lumbar puncture where the results did not influence their management, the inconsistency in the laboratory’s technique for performing tests on cerebrospinal fluid and the very low yield of detecting patients with subarachnoid haemorrhage and a potentially treatable causative lesion.
HIGH USE OF COMPLEMENTARY THERAPIES IN A NEW SOUTH WALES RURAL COMMUNITY
Authors: Wilkinson Jenny M. , Simpson Maree D.
Published: March 2003

In this study a postal questionnaire was used to investigate the use of complementary therapies (CT) in a rural region of New South Wales (NSW). A total of 70.3% of respondents reported using one or more therapies with 62.7% having visited a complementary practitioner. Vitamin/mineral therapy (68.7%), chiropractic (26.1%) and massage therapy (25.1%) were the most frequently used therapies, with the most commonly visited practitioners being chiropractors (55.3%) and those trained in vitamin/mineral therapy (47.9%). Of the vitamins, vitamin C and multivitamins were used most often, with garlic and Echinacea being the most used herbal products. The main source of information were friends (64.5%) with most people indicating that CT could improve quality of life and provide relief of symptoms. Results suggest that CT use in rural communities is high and that, in light of these findings, there is a need for training in CT to be included in the undergraduate and continuing education of health professionals. Furthermore, these professionals should be alert to the potential for increased numbers of herb–drug interactions in rural communities.
Plankton dynamics: observed and modelled responses to physical conditions in Prince William Sound, Alaska
Authors: Eslinger David L. , Cooney R. Ted , Mcroy C. Peter , Ward Alison , Kline Thomas C. , Simpson E. Paul , Wang Jia , Allen Jennifer R.
Published: March 2003

Plankton populations in Prince William Sound, Alaska, exhibited pronounced seasonal, annual and longer‐period variability in composition and standing stock in response to physically influenced differences in nutrient availability, and possibly currents that modify local biomass by exchanges with water from the bordering Gulf of Alaska. During springs in which early, strong physical stratification developed, intense, short‐lived phytoplankton blooms occurred. These blooms had relatively short residence times in the water column. In contrast, during springs in which slower, weaker stratification developed, phytoplankton blooms were prolonged and took longer to peak. These slower blooms prolonged the period of phytoplankton production, prolonged interaction with the springtime grazing community and led to the incorporation of more organic matter into pelagic food webs. A coupled biological‐physical simulation of plankton production was used to examine the implications of seasonally varying air and mixed‐layer temperatures, surface winds and incident light on the timing, duration, annual production and standing stock of plankton. Our modelling results reproduced the observed characteristics of the springtime production cycle, and the magnitude of zooplankton stocks for the period 1992–97 but not for 1981–91. These results suggest that for most of the 1990s, bottom‐up influences on nutrient supplies controlled levels of primary consumers, whereas for the 11 years before that, other unknown factors dominated this process. We present the results of a comprehensive, multiyear study of relationships between plankton and physical limitations, and a retrospective analysis of earlier conditions to explore the possible causes for these differences.
Helicobacter pylori‐Related Iron Deficiency Anemia: A Review
Authors: Barabino Arrigo
Published: March 2003

Several clinical reports have demonstrated that Helicobacter pylori gastric infection has emerged as a new cause of refractory iron deficiency anemia, unresponsive to iron therapy, and not attributable to usual causes such as intestinal losses or poor intake, malabsorption or diversion of iron in the reticulo‐endothelial system.

Although the interaction between infection and iron metabolism is now well consolidated, our understanding of the pathogenetic mechanism underlying the anemia is still wanting. Microbiological and ferrokinetic studies seem to suggest that Helicobacter pylori infected antrum could act as a sequestering focus for serum iron by means of outer membrane receptors of the bacterium, that in vitro are able to capture and utilize for growth iron from human lactoferrin.

The proposed hypothesis does not answer why this complication is such a rare disease outcome in a common human infection but it may be used as a template for further controlled studies to determine the mechanisms of this atypical, medically important putative sequelae of H. pylori infection.
Effect of propylene glycol and undegradable protein source on rumen fermentation, blood metabolism and milk production in lactating dairy cows
Authors: BAIYILA Turigen , HAN Jifu , KANDA Shuhei , ITOH Masahiro , WASHIO Yuichiro , SUZUKI Tamotu , HORIKAWA Hiroshi , KAMADA Toshihiko , ITABASHI Hisao
Published: March 2003

Eight lactating Holstein cows were divided into two groups (n = 4) and used in a double reversal trial with three periods of 14 days each, to evaluate diets containing propylene glycol (PG) and ruminally undegradable protein (RUP) blend on milk yield and composition, ruminal fermentation and blood metabolism. The control diet contained 20% chopped Sudangrass hay, 20% cubed alfalfa hay, 12% corn silage, and 48% of the respective concentrate mixtures (dry matter basis). The experimental diet (PG + RUP) partially replaced the concentrate mixture from the control diet with 1.4% PG and 2.1% RUP. Both diets contained about 16% crude protein and 71% total digestible nutrients. Dry matter intake was similar between the two diets. Daily production of milk, milk lactose and milk solids‐not‐fat increased by 9.0%, 11.3% and 9.3%, respectively (P < 0.1), for cows fed diets with PG + RUP; milk composition was unchanged. Although the concentration of ruminal total volatile fatty acids was unchanged, the proportion of propionic acid increased, and the proportion of acetic acid decreased with PG + RUP. The concentration of ruminal ammonia nitrogen and number of ciliate protozoa was not significantly affected by PG + RUP. The concentration of glucose in blood plasma increased, the concentration of urea nitrogen was unaffected, and the concentration of some essential free amino acids decreased with PG + RUP. It is suggested that these changes might be caused predominantly by PG, and the addition of PG may exert a favorable effect on milk production through increased metabolism.
Use of a box to prevent agonistic behavior after regrouping in isolated and non‐isolated pigs
Authors: ISHIWATA Toshie , UETAKE Katsuji , TANAKA Toshio
Published: March 2003

The effects of a box in the pen on the agonistic behavior of pigs after regrouping was determined in 24 pigs from five litters that were kept in three pens after weaning. For the experiment, the pigs were allocated to six pens with four animals each and kept with their peers for 2 weeks. The lightest pig from each pen was removed and isolated for 2 weeks, and then regrouped with its original peers. At the time of regrouping, half of the pens were equipped with the box. The number and duration of agonistic behavior events were particularly large and long in the pen without a box on the first day after regrouping, and for the isolated pig on the first day (all P < 0.05). The number of times the box was accessed was large for the isolated pig on the first day after regrouping (P < 0.01). The number of agonistic behavior events and the times the box was accessed was correlated on the first day after regrouping (rs = 0.79, P < 0.01). The number of agonistic behavior events on the first day after regrouping was greater in the pens without a box than in the pens with a box (P < 0.01). It was suggested that the box had the effect of reducing agonistic behavior after regrouping.
Manufacturing challenges in the commercial production of recombinant coagulation factor VIII
Authors: Jiang R. , Monroe T. , Mcrogers R. , Larson P. J.
Published: March 2003

Summary.  Advances in gene technology have led to the development of a method to manufacture recombinant coagulation Factor VIII (rFVIII) for haemophilia A. Because rFVIII is a large and complex protein, its commercialization has required that many challenges in manufacturing, purification and processing be overcome. In order to license the first generation of rFVIII (Kogenate®) in 1993, Bayer Corporation invested over 10 years in research and manufacturing development. Seven additional years were subsequently devoted to research and manufacturing improvements in order to accomplish the recent licensing of a second rFVIII product (KOGENATE® Bayer or Kogenate® FS). This product differs from its predecessor, in that human albumin is removed from the purification and the formulation steps. In addition, fewer chromatography steps are involved resulting in greater yields per mL of conditioned medium, and a solvent‐detergent viral inactivation step replaces the heat‐processing step used for the previous product. Despite these changes in the manufacturing, the protein backbone and carbohydrate structure of the final rFVIII molecule are identical. The complexity of the production processes is reflected by over 100 000 manufacturing data entries and by 600 quality control tests for each batch of rFVIII. Manufacturers are continuing to develop the next generation of rFVIII, which will be produced without the addition of any human or animal proteins or byproducts. Investments in research, development and manufacturing technology are expected to result in the development of new products with enhanced safety profiles, and in an increase in the production capacity for products that are chronically in short supply.
Soil‐surface CO2 efflux and its spatial and temporal variations in a young ponderosa pine plantation in northern California
Authors: Xu Ming , Qi Ye
Published: March 2003

Soil‐surface CO2 efflux and its spatial and temporal variations were examined in an 8‐y‐old ponderosa pine plantation in the Sierra Nevada Mountains in California from June 1998 to August 1999. Continuous measurements of soil CO2 efflux, soil temperatures and moisture were conducted on two 20 × 20 m sampling plots. Microbial biomass, fine root biomass, and the physical and chemical properties of the soil were also measured at each of the 18 sampling locations on the plots. It was found that the mean soil CO2 efflux in the plantation was 4.43 µmol m−2 s−1 in the growing season and 3.12 µmol m−2 s−1 in the nongrowing season. These values are in the upper part of the range of published soil‐surface CO2 efflux data. The annual maximum and minimum CO2 efflux were 5.87 and 1.67 µmol m−2 s−1, respectively, with the maximum occurring between the end of May and early June and the minimum in December. The diurnal fluctuation of CO2 efflux was relatively small (< 20%) with the minimum appearing around 09.00 hours and the maximum around 14.00 hours. Using daytime measurements of soil CO2 efflux tends to overestimate the daily mean soil CO2 efflux by 4–6%. The measurements taken between 09.00 and 11.00 hours (local time) seem to better represent the daily mean with a reduced sampling error of 0.9–1.5%. The spatial variation of soil CO2 efflux among the 18 sampling points was high, with a coefficient of variation of approximately 30%. Most (84%) of the spatial variation was explained by fine root biomass, microbial biomass, and soil physical and chemical properties. Although soil temperature and moisture explained most of the temporal variations (76–95%) of soil CO2 efflux, the two variables together explained less than 34% of the spatial variation. Microbial biomass, fine root biomass, soil nitrogen content, organic matter content, and magnesium content were significantly and positively correlated with soil CO2 efflux, whereas bulk density and pH value were negatively correlated with CO2 efflux. The relationship between soil CO2 efflux and soil temperature was significantly controlled by soil moisture with a Q10 value of 1.4 when soil moisture was <14% and 1.8 when soil moisture was >14%. Understanding the spatial and temporal variations is essential to accurately assessment of carbon budget at whole ecosystem and landscape scales. Thus, this study bears important implications for the study of large‐scale ecosystem dynamics, particularly in response to climatic variations and management regimes.
CO2 emission from mineral soils following land‐cover change in Brazil
Authors: Bernoux Martial , Da ConceiçÃo Maria , Carvalho Santana , Volkoff Boris , Cerri Carlos Clemente
Published: March 2003

This paper presents a first approximation of net CO2 fluxes from mineral soil due to land use, land‐use changes and forestry (LULUCF) activities in Brazil for the periods 1970–90 and 1975–95. The methodology employed is an adaptation of the approach proposed by the IPCC in ‘Revised 1996 guidelines for national greenhouse gas inventories’, which is based on the variations in soil C stocks as a function of changes in land‐use activities. The calculation was done separately for each Brazilian state and subsequently summarized for all of Brazil. The annual fluxes for Brazil indicate a net emission of CO2 to the atmosphere, which decreased from 93.3 Tg CO2 for the period 1970–90 to 46.4 Tg CO2 for the period 1975–95. This corresponded to yearly net emission rates of 11.0 g CO2 m−2 year−1 for the 1970–90 period and 5.5 g CO2 m−2 year−1 for the 1975–95 period. Within each administrative region, considerable differences in the yearly emission rates between the states could be observed. Several sources of uncertainties could be identified. The most important uncertainties were linked to the impact factor values, which represent changes in native C stock associated with conversion of the native vegetation to agricultural use.
Elevated UV‐B radiation alters fluxes of methane and carbon dioxide in peatland microcosms
Authors: Niemi Riikka , Martikainen Pertti J. , Silvola Jouko , Wulff Anu , Turtola Satu , Holopainen Toini
Published: March 2003

Increases in solar ultraviolet‐B radiation (UV‐B; 280–320 nm) reaching the earth have been estimated to continue until 2050s in the boreal and subarctic regions with an abundant peatland cover. Peatlands are significant sinks for carbon dioxide (CO2) and sources for methane (CH4). To assess whether the future increases in UV‐B could affect the fluxes of CO2 and CH4 in peatlands via an impact on vegetation, we exposed peatland microcosms to modulated 30% supplementation of erythemally weighted UV‐B at an outdoor facility for one growing season. The experimental design included appropriate controls for UV‐A and ambient radiation. The UV‐B caused a significant reduction in gross photosynthesis, net ecosystem CO2 exchange, and CH4 emission of the peatland microcosms. These changes in the carbon gas cycling can be partly explained by UV‐B‐induced morphological changes in Eriophorum vaginatum which acts as a conduit for CH4. Leaf cross section and the percentage of CH4‐conducting aerenchymatous tissue in E. vaginatum were significantly reduced by UV‐B. Methanol‐extractable UV‐B absorbing compounds decreased under both UV‐B and UV‐A in Sphagnum angustifolium, and tended to accumulate under UV‐B in S. papillosum. Membrane permeability to magnesium (Mg) and calcium (Ca) ions was higher in UV‐B exposed S. angustifolium. Amount of chlorophyll and carotenoid pigments was increased by UV‐A in S. magellanicum. The observed changes in Sphagnum mosses did not coincide with those in carbon gas fluxes but occurred at the time of the highest UV intensity in the mid summer. Our findings indicate that increasing UV‐B may have more substantial effects on gas exchange in peatlands than previously thought.
Essential role of S‐adenosylmethionine decarboxylase in mouse embryonic development
Authors: Nishimura Kazuhiro , Nakatsu Fubito , Kashiwagi Keiko , Ohno Hiroshi , Saito Takashi , Igarashi Kazuei
Published: March 2003

Background: S‐Adenosylmethionine decarboxylase (AdoMetDC) is one of the key enzymes involved in the biosynthesis of spermidine and spermine, which are essential for normal cell growth. To examine the role of polyamines in embryogenesis, we carried out targeted disruption of the mouse Amd1 gene, encoding AdoMetDC, to generate mice that can not synthesize spermidine and spermine.

Results: Amd1 heterozygous mice were viable, normal and fertile. However, homozygous Amd1−/− embryos died early in embryonic development, between E3.5 and E6.5 days post‐coitus. Homozygous (Amd1−/−) blastocysts at E3.5 arrested cell proliferation immediately after the onset of cell culture, and this arrest was rescued by the addition of spermidine. Chromosomal DNA breakage did not occur in Amd1−/− blastocysts at E3.5, as determined by TUNEL assay.

Conclusions: These results indicate that AdoMetDC plays an essential role in embryonic development and that polyamines are required for cell proliferation in the embryo after E3.5.
Hypoxia‐inducible factor‐1α induces cell cycle arrest of endothelial cells
Authors: Iida Takeshi , Mine Shinichiro , Fujimoto Hiroko , Suzuki Koji , Minami Yasuhiro , Tanaka Yoshiya
Published: March 2003

Background: Hypoxia can induce tissue injury, including apoptosis of endothelial cells. However, little is known about the effects of hypoxia on endothelial cell function. We assessed the effects of hypoxia inducible factor (HIF)‐1α on the functional characteristics of endothelial cells, particularly on cell cycle regulators, by cationic liposome‐mediated transfection of HIF‐1α‐expression vector into the cells.

Results: Transfection of the HIF‐1α gene in endothelial cells resulted in (a) reduced proliferation and detachment of the cells; (b) up‐regulation of intracellular p21waf1/cip1 and down‐regulation of bcl‐2; (c) reduced activities of cyclin‐dependent kinase (CDK)‐4 and CDK‐6; (d) cell cycle arrest at G0/G1 phase; and (e) apoptosis of the cells.

Conclusions: HIF‐1α can induce cell cycle arrest, resulting in the reduced proliferation and apoptosis of endothelial cells, and the hypoxia‐induced cell death may be involved by suppression of anti‐apoptotic molecule, bcl‐2.
Cannabis dependence in young adults: an Australian population study
Authors: Coffey Carolyn , Carlin John B. , Degenhardt Louisa , Lynskey Michael , Sanci Lena , Patton George C.
Published: March 2003

Objectives The symptomatology of cannabis dependence remains ill‐defined and its importance controversial. Compared with alcohol dependence, the symptom profile of cannabis dependence has received little attention. We aimed to (a) report cannabis use in a representative population of young adults, (b) examine cannabis dependence symptoms according to frequency in the dependence syndrome and (c) contrast the symptomatology of cannabis and alcohol syndromes.

Methods 1601 young adults (mean age 20.7 years) from an Australian longitudinal cohort study (N = 2032) were surveyed in 1998. Regular substance users were assessed for DSM‐IV cannabis and alcohol dependence. Prevalence estimates allowed for sampling variation and attrition.

Results Fifty‐nine per cent reported life‐time use of cannabis, 17% used at least weekly and 7% (11% males, 4% females) met criteria for cannabis dependence. Symptom prevalence in dependent cannabis users was: persistent desire 91%; unintentional use 84%; withdrawal 74%; excessive time obtaining/using 74%; continued use despite health problems 63%; tolerance 21%; and social consequences 18%. The combination of withdrawal, persistent desire and unintentional use was reported by 57%. Dependent cannabis users reported compulsive and out‐of‐control use more frequently than dependent alcohol users, withdrawal similarly and tolerance considerably less often.

Conclusions Cannabis use appears to be normative behaviour in young Australians. Progression beyond weekly use of cannabis carries a significant risk of dependence that should be considered in the public health response. The differing profiles of cannabis and alcohol dependence, particularly with regard to craving, draws attention to the need for further study of cannabis dependence as an important and distinct disorder in young adults.
Different renal effects of two inhibitors of catechol‐O‐methylation in the rat: Entacapone and CGP 28014
Authors: HANSELL  , ODLIND  , MÄNNISTÖ
Published: March 2003

Dopamine is a natriuretic hormone that is abundantly synthesized in the kidney and is involved in sodium homeostasis. It is metabolized by monoamine oxidase (MAO) and catechol‐O‐methyl transferase (COMT) to form 3‐methoxytyramine and dihydroxyphenylacetic acid (DOPAC) and finally homovanillic acid (HVA). In order to investigate whether dopamine metabolism is involved in renal sodium regulation, we tested the renal effects of the nitrocatechol entacapone (COMT inhibitor), in comparison with those of the pyridine derivative CGP 28014, in the anaesthetized rat. Entacapone injection resulted in a more than 5‐fold increase in sodium excretion, while the renal excretion of dopamine only transiently increased by 20%. DOPAC excretion showed a more than 2‐fold increase which persisted throughout the study. Pretreatment with the selective dopamine DA1‐receptor antagonist SCH23390 reduced the entacapone‐induced natriuretic response by 69%. Glomerular filtration rate (GFR) and mean arterial blood pressure (MAP) remained unchanged. Injection of CGP 28014 did not produce a natriuretic response; nevertheless, both dopamine and DOPAC excretion increased by 78% and more than 2‐fold, respectively. GFR and MAP remained unchanged. In conclusion, COMT inhibition using entacapone results in a mainly DA1 receptor mediated natriuresis involving inhibition of tubular transport processes, supporting a role for dopamine metabolism in sodium homeostasis. Although CGP 28014 increases the renal excretion of both dopamine and DOPAC it does not affect renal sodium handling indicating a different mechanism of action.
Cardiovascular and muscular adaptations to combined endurance and strength training in elderly women
Authors: FERKETICH  , KIRBY  , ALWAY
Published: March 2003

Twenty‐one women aged 60–75 years were examined to determine whether combined endurance and strength training resulted in greater increase in peak oxygen consumption, sub‐maximal time to fatigue, cardiac output, stroke volume, and leg extension load when compared to endurance training alone. Subjects in both the endurance training (E) and endurance and strength (E & S) groups trained 3 days a week, for 12 weeks, at an intensity of 70–80% V˙O2 peak for 30 min on a cycle ergometer. Subjects in the E & S groups also used resistance equipment to train the knee extensors. The workload for resistance training was based on an initial assessment of 10 repetitions maximum (10 RM), with 80% of that value used for training, three times weekly. Peak oxygen consumption increased to an average of 24.8 and 29.9% in the E and E & S groups, respectively, with no difference between groups. Subjects in the E & S and E groups significantly increased sub‐maximal endurance time by 396 and 165%, respectively. Cardiac output, stroke volume, and arteriovenous oxygen difference at 80% peak V˙O2 were unchanged by either of the training methods. A needle biopsy was taken from the vastus lateralis before and after 12 weeks of training. Chi‐square analysis of fibre area data showed an increase in the frequency of larger type I fibres in the post‐training data from the E & S group, but an increase in the frequency of smaller fibres in the E group post‐training; however, mean fibre area was not significantly changed by training. These data suggest that greater improvements in sub‐maximal time to fatigue and strength is achieved when resistance training is added to an aerobic training programme in healthy elderly women.
Inhibitory mechanisms for cross‐bridge cycling: the nitric oxide‐cGMP signal transduction pathway in smooth muscle relaxation
Authors: MURPHY  , WALKER
Published: March 2003

Relaxation follows sequestration of Ca2+ mobilized by an excitatory stimulus in striated muscle. Removal of excitatory stimuli also relaxes smooth muscle in vitro after reductions in the myoplasmic [Ca2+] and dephosphorylation of the myosin regulatory light chains. However, there are several experimental procedures that produce relaxation in the presence of excitatory stimuli and elevated Ca2+‐dependent cross‐bridge phosphorylation. Of potential widespread physiological importance are treatments that increase myoplasmic [cGMP] owing to the ubiquity of nitric oxide (NO) as a signalling molecule for endothelial‐mediated vasodilation and inhibitory nerves in most types of smooth muscle. Several mechanisms are implicated in the NO‐cGMP mediated relaxation. Most studies support reductions in myoplasmic Ca2+. However, there is evidence that increases in cGMP also lower the Ca2+‐sensitivity of cross‐bridge phosphorylation. This would contribute to a decline in force through actions on the myosin light chain kinase/phosphatase system. In addition, changes in the dependence of force on phosphorylation are observed in tissues partially relaxed by treatments that elevate cGMP. This demonstrates that either the attachment and cycling of phosphorylated cross‐bridges is impaired or blocked, or that the formation of dephosphorylated, force‐generating cross‐bridges (‘latch‐bridges’) is reduced. Protein kinase G‐catalysed phosphorylation of either a thin filament protein that blocks attachment of cross‐bridges or a protein that inhibits myosin light chain phosphatase may explain the NO‐induced relaxation with elevated cross‐bridge phosphorylation.
Attenuating the decline in ATP arrests the exercise training‐induced increases in muscle GLUT4 protein and citrate synthase activity
Authors: YASPELKIS  , CASTLE  , DING  , IVY
Published: March 2003

Thirty‐two female Sprague–Dawley rats were assigned to one of four groups: control (CON); exercise training (TR); exercise training + clenbuterol treatment (0.8 mg kg body wt−1 d−1) (TR + CL) or exercise training + clenbuterol treatment + 2% β‐guanidinoproprionic acid diet (TR + CL + β) to examine whether alterations in the high energy phosphate state of the muscle mediates exercise training‐induced increases in skeletal muscle GLUT4 protein concentration and citrate synthase activity. Exercise training consisted of running the rats 5 d week−1 for 8 weeks on a motor‐driven treadmill (32 m min−1, 15% grade). Gastrocnemius GLUT4 protein concentration and citrate synthase activity were significantly elevated in the TR animals, but these adaptations were attenuated in the TR + CL animals. Providing β‐GPA in combination with clenbuterol enabled training to elevate GLUT4 protein concentration and citrate synthase activity, with the increase in GLUT4 being greater than that observed for the TR animals. Skeletal muscle ATP levels were reduced in the TR + CL + β animals while ATP levels in the TR + CL animals were significantly elevated compared with CON. An acute 40‐min bout of electrical stimulation of the sciatic nerve was found to lower skeletal muscle ATP levels by ≈50% and elevate cAMP levels in all groups. No difference in post‐contraction cAMP levels were observed among groups. However, post‐contraction ATP levels in the TR + CL animals were significantly greater than the other groups. Collectively, these findings suggest that exercise training‐induced increases in skeletal muscle GLUT4 protein concentration and citrate synthase activity are initiated in response to a reduction in the skeletal muscle ATP concentration.
Creatine uptake in isolated soleus muscle: kinetics and dependence on sodium, but not on insulin
Authors: Willott  , Young  , Leighton  , Kemp  , Boehm  , Radda  , Clarke
Published: March 2003

The increased use of creatine by athletes as a dietary supplement to improve their physical performance assumes that increased serum creatine levels will increase intracellular skeletal muscle creatine. Despite this common assumption, skeletal muscle creatine uptake awaits full characterization. Consequently, we have investigated 14C‐labelled creatine uptake in isolated, incubated rat soleus (type I) muscle preparations at 37 °C. We found that the apparent Km for creatine uptake was 73 μM and the Vmax was 77 nmol h–1 gww–1. Creatine uptake was 82% inhibited by 2 m
Mβ‐guanidinopropionic acid, the structural analogue of creatine. In addition, a decrease in buffer Na+ concentration, from 145 to 25 m
M, reduced the rate of 14C‐labelled creatine uptake by 77%, indicating that uptake is largely Na+‐dependent in soleus muscle. Insulin had no effect on the rate of creatine uptake in vitro. The total creatine content was 34% lower, but the rate of creatine uptake in the presence of 100 μM extracellular creatine was 45% higher, in soleus than in extensor digitorum longus (type II) muscle. However, at 1 m
M extracellular creatine, the maximal rate of uptake was not significantly different for the two muscle types, implying that soleus muscle has a lower Km for creatine uptake. We suggest that intracellular creatine levels may play a role in the regulation of skeletal muscle creatine uptake.
Calcium response to adenosine and ATP in rabbit afferent arterioles
Authors: Gutiérrez  , Kornfeld  , Persson
Published: March 2003

The effects of purine compounds in the renal vasculature are almost exclusively restricted to pre‐glomerular vessels. Although their physiological role as extracellular messengers is not clear, there are extensive data indicating the importance of adenosine and ATP in the regulation of renal haemodynamics. This study was undertaken to characterize the calcium response of rabbit afferent arteriole to adenosine, ATP and other nucleotides. Experiments were performed in isolated afferent arterioles, microdissected from rabbit kidneys and loaded with fura‐2. Intracellular calcium concentration ([Ca2+]i) was measured by video in proximal and distal parts of the afferent arteriole. Application of 100 μM adenosine or ATP increased [Ca2+]i in both arteriolar regions. In all cases the response had two well distinguishable phases: a quick peak increase and a plateau phase that equilibrated at a [Ca2+]i significantly higher than the basal level. UTP (100 μM) had no effect on the arteriole. Removal of extracellular calcium (2.5 m
M EGTA) abolished only the plateau phase in response to adenosine, without significantly changing the peak increase. In contrast, the response to ATP was completely abolished in both arteriolar regions, where [Ca2+]i decreased upon application of the agonist and rapidly increased after restoration of calcium concentration to plasma level. We conclude that P1 and P2X receptors are present along the rabbit afferent arteriole and mediate calcium mobilization, with the same distribution in the proximal and distal segments.
Nitric oxide and prostaglandin pathways interact in the regulation of hypercapnic cerebral vasodilatation
Authors: Heinert  , Nye  , Paterson
Published: March 2003

To test whether nitric oxide and prostaglandin pathways interact in hypercapnic cerebral vasodilatation, cerebral blood flow (CBF) was measured in enflurane anaesthetized Sprague–Dawley rats using the hydrogen clearance method. Isometric tension was measured in rat middle cerebral arteries in vitro. The neuronal NO synthase inhibitor 7‐nitroindazole (7‐NI 60 mg kg–1 i.p.) reduced the hypercapnic CBF response by 62 ± 7% (but not the hypoxic response) and indomethacin (IMC 6 mg kg–1 i.v.) reduced the hypercapnic CBF response by 60 ± 5%. Combined application caused only an 80 ± 1% reduction. The attenuation of hypercapnic CBF by IMC was diminished by 7‐NI and similarly 7‐NI had less effect in the presence of IMC. Spermine‐NO (50 μM 0.5 μL min–1 intracortically) increased eucapnic and hypercapnic CBF in the presence of IMC. In isolated middle cerebral arteries, combined application of sodium nitroprusside (SNP 3 n
M) and prostacyclin (30 n
M) had a synergistic vasodilatory effect. Milrinone (PDE‐III inhibitor) also potentiated prostacyclin‐mediated vasodilatation. Our results suggest that the NO‐ and IMC‐sensitive pathways involved in the hypercapnic response are distinct, however, both may interact synergistically. A similar synergism was observed between the effects of SNP and prostacyclin.
Tachykinins stimulate acid and pepsinogen secretion in the isolated porcine stomach
Authors: Schmidt P.T. , Rasmussen T.N. , Holst J.J.
Published: March 2003

The precise role of tachykinins in regulation of acid and pepsinogen secretion has not been established. Tachykininergic effects on acid and pepsinogen secretion could be mediated either directly in the proximal stomach or through other indirect mechanisms, i.e. gastrin secretion. We studied the effects of the two tachykinins, substance P and neurokinin A, and of capsaicin, on acid and pepsinogen output, in isolated porcine non‐antral stomach preparation. The release of substance P and neurokinin A was studied during electrical stimulation of the vagal nerves, and during capsaicin infusion. Substance P infusion (10–8 M) increased acid secretion from 30 ± 8 to 68 ± 17 fmol min–1 (n=6, P < 0.05) and pepsinogen output from 46 ± 12 to 160 ± 47 units of pepsin min–1 (n=9, P < 0.05). Neurokinin A also stimulated both acid and pepsinogen secretion, while capsaicin had no effect on either parameter. Electrical stimulation of the vagal nerves increased the release of both peptides. We conclude that tachykinins may be involved in regulation of acid and pepsinogen secretion.