bluuebunny/crossref_metadata_2025 huggingface dataset:
Seasonal variability in the biophysical properties of stratum corneum from different anatomical sites
Authors: Black D. , Pozo A. , Lagarde J. M. , Gall Y.
Published: March 2003

Background/purpose: A 10‐month‐long study on a panel of 24 young female subjects was carried out to determine whether various biophysical aspects of the stratum corneum (SC) varied with season.

Methods: Three different anatomical sites (calf, inner forearm and crow’s foot wrinkle area of the face) were assessed in February, April, July and December of the same year. The assessments made were skin surface hydration using an electrical capacitance technique, transepidermal water loss by evaporimetry, number of corneocytes released using a turbine stimulation method, and skin surface topography using optical profilometry.

Results: The results showed significant anatomical differences: with the crow’s foot site > forearm > calf, for skin surface hydration and corneocyte numbers; and the crow’s foot site > forearm and calf, with no difference between the latter two sites, for TEWL measurements. With these techniques, seasonal differences were observed mainly in the calf, to a lesser extent in the forearm, but not in the crow’s foot area. These mainly involved increases in these three parameters in July, as opposed to the other time‐points. Parameters of skin surface topography however, showed no consistent seasonal pattern, but markedly higher values were observed for the forearm in comparison to the calf and crow’s foot sites, which were similar. From meteorological data obtained, the average daily maximum temperature and hours of sunshine increased to peak values in July, as did the absolute humidity derived from relative humidity data.

Conclusion: We conclude that the results are most likely to represent changes in the SC due to climatic factors, with the calf and forearm sites being most affected in comparison to the face (crow’s foot wrinkle area), which seems unaffected. The reasons for this latter site remaining unchanged may be due to its greater UV exposure, sebum content, and that the use of facial cosmetics was allowed.
Nonlinear model of skin mechanical behaviour analysis with finite element method
Authors: Retel V. , Vescovo P. , Jacquet E. , Trivaudey F. , Varchon D. , Burtheret A.
Published: March 2003

Background/aims: A problem commonly encountered in plastic and reconstructive surgery is the prediction of the stress put on the skin when various types of skin flaps are used.

Methods/results: We developed a mathematical model based on the finite element method, in order to determine the stress field, by simulating the mechanical behaviour of human skin during wound closure. We chose to take into account the low compressive strength by modifying the mechanical parameters of the model at each step of the calculation. The model has been developed and tested on a diamond‐shaped incision and applied on a Limberg incision.

Conclusion: The results presented are the Von Mises stress in the area of skin around the scar and, when possible, the resultant closure force. They show the relevance of the method.
Effect of elastic compression stockings in patients with varicose veins and healthy controls measured by strain gauge plethysmography
Authors: Hirai M. , Iwata H. , Hayakawa N.
Published: March 2003

Background/aims:  Oedema is one of the most frequent signs of chronic venous insufficiency and may be present at all stages of this disorder. The aim of this study was to compare the effects of four different types of elastic compression stockings on oedema prevention in patients with varicose veins.

Methods:   An increase in foot volume after elevation of the leg was evaluated by strain gauge plethysmography in 20 limbs with varicose veins and 14 normal limbs, and the effects of four different compression stockings – 8, 14, 22 and 30–40 mmHg – were compared.

Results:   All stockings significantly reduced the foot volume increase compared with the no stockings patient group and the normal group. There was no significant difference in the volume increase in the normal group for all four stockings, while there was a significantly smaller volume increase in the 22 mmHg stocking compared to the 14 mmHg stocking in the patient group. Between the 22 mmHg and 30–40 mmHg stockings or between the 14 mmHg and 8 mmHg stockings, there was no significant difference in the volume increase.

Conclusion:   Elastic stockings, even with a pressure as low as 8 mmHg, can prevent oedema in patients with varicose veins, as well as in normal controls. However, the 22 mmHg and 30–40 mmHg stockings were better at preventing foot oedema in patients with varicose veins than those exerting less compression.
Endocytosis of NBD‐Sphingolipids in Neurons: Exclusion from Degradative Compartments and Transport to the Golgi Complex
Authors: Babià Teresa , Ledesma Maria Dolores , Saffrich Rainer , Kok Jan Willem , Dotti Carlos G. , Egea Gustavo
Published: March 2003

Sphingolipids are abundant constituents of neuronal membranes that have been implicated in intracellular signaling, neurite outgrowth and differentiation. Differential localization and trafficking of lipids to membrane domains contribute to the specialized functions. In non‐neuronal cultured cell lines, plasma membrane short‐chain sphingomyelin and glucosylceramide are recycled via endosomes or sorted to degradative compartments. However, depending on cell type and lipid membrane composition, short‐chain glucosylceramide can also be diverted to the Golgi complex. Here, we show that NBD‐labeled glucosylceramide and sphingomyelin are transported from the plasma membrane to the Golgi complex in cultured rat hippocampal neurons irrespective of the stage of neuronal differentiation. Golgi complex localization was confirmed by colocalization and Golgi disruption studies, and importantly did not result from conversion of NBD‐glucosylceramide or NBD‐sphingomyelin to NBD‐ceramide. Double‐labeling experiments with transferrin or wheat‐germ agglutinin showed that NBD‐sphingolipids are first internalized to early/recycling endosomes, and subsequently transported to the Golgi complex. The internalization of these two sphingolipid analogs was energy and temperature dependent, and their intracellular transport was insensitive to the NBD fluorescence quencher sodium dithionite. These results indicate that vesicles mediate the transport of internalized NBD‐glucosylceramide and NBD‐sphingomyelin to the Golgi complex.
Identification of a Conserved Loop in Mog1 that Releases GTP from Ran
Authors: Steggerda Susanne M. , Paschal Bryce M.
Published: March 2003

Ran regulates nuclear import and export pathways by coordinating the assembly and disassembly of transport complexes. These transport reactions are linked to the GTPase cycle and subcellular distribution of Ran. Mog1 is an evolutionarily conserved nuclear protein that binds RanGTP and stimulates guanine nucleotide release, suggesting Mog1 regulates the nuclear transport functions of Ran. In the present study, we have characterized the nuclear import pathway of Mog1, and we have defined the domain in Mog1 that stimulates GTP release from Ran. In permeabilized cells, nuclear import of Mog1 is independent of exogenously added factors, and is inhibited by wheat germ agglutinin, indicating that translocation of Mog1 involves physical interactions with the nuclear pore complex. In contrast to RanGEF, which is restricted to the nucleus, Mog1 shuttles between the nucleus and the cytoplasm. Single‐point mutations in acidic residues of Mog1 (Asp25, Asp34, Glu37) dramatically reduce GTP release and Ran binding activity, whereas mutation of a single basic residue (Arg30) renders Mog1 hyperactive for GTP release. These mutations map within a conserved, solvent‐exposed loop in Mog1 that is functionally similar to the β‐wedge used by RanGEF to promote nucleotide release from Ran. These data suggest that Mog1 and RanGEF use similar mechanisms to facilitate guanine nucleotide release from Ran.
Sgf1p, a New Component of the Sec34p/Sec35p Complex
Authors: Kim Dong‐Wook , Massey Thomas , Sacher Michael , Pypaert Marc , Ferro‐Novick Susan
Published: March 2003

Here we report the identification of SGF1 as a high‐copy suppressor of the sec35–1 mutant. SGF1 encodes an essential hydrophilic protein of ∼ 100 kDa. Using the yeast two‐hybrid system and coprecipitation studies, we demonstrate that Sgf1p is a new subunit of the multiprotein Sec34p/Sec35p complex. Reduced levels of Sgf1p lead to the accumulation of a variety of membranes as well as a kinetic block in endoplasmic reticulum to Golgi traffic. Immunofluorescence studies demonstrate that Sec34p is found throughout the Golgi, with a high concentration on early Golgi. Although an earlier study suggested that Sec34p (Grd20p) is not required for protein secretion, we show here that the sec34–2 and sec35–1 mutations lead to a pleiotropic block in the secretion of all proteins into the growth medium.
Myosin VI Binds to and Localises with Dab2, Potentially Linking Receptor‐Mediated Endocytosis and the Actin Cytoskeleton
Authors: Morris Shelli M. , Arden Susan D. , Roberts Rhys C. , Kendrick‐Jones John , Cooper Jonathan A. , Luzio J. Paul , Buss Folma
Published: March 2003

Myosin VI, an actin‐based motor protein, and Disabled 2 (Dab2), a molecule involved in endocytosis and cell signalling, have been found to bind together using yeast and mammalian two‐hybrid screens. In polarised epithelial cells, myosin VI is known to be associated with apical clathrin‐coated vesicles and is believed to move them towards the minus end of actin filaments, away from the plasma membrane and into the cell. Dab2 belongs to a group of signal transduction proteins that bind in vitro to the FXNPXY sequence found in the cytosolic tails of members of the low‐density lipoprotein receptor family. The central region of Dab2, containing two DPF motifs, binds to the clathrin adaptor protein AP‐2, whereas a C‐terminal region contains the binding site for myosin VI. This site is conserved in Dab1, the neuronal counterpart of Dab2. The interaction between Dab2 and myosin VI was confirmed by in vitro binding assays and coimmunoprecipitation and by their colocalisation in clathrin‐coated pits/vesicles concentrated at the apical domain of polarised cells. These results suggest that the myosin VI–Dab2 interaction may be one link between the actin cytoskeleton and receptors undergoing endocytosis.
Translocation of Phosphatidylthreonine and ‐serine to Mitochondria Diminishes Exponentially with Increasing Molecular Hydrophobicity
Authors: Heikinheimo Liisa , Somerharju Pentti
Published: March 2003

Some cultured cells contain significant amounts of a rarely recognized phospholipid, phosphatidylthreonine. Since phosphatidylthreonine is a structural analog of phosphatidylserine, the question rises whether it is transported to mitochondria and decarboxylated to phosphatidylisopropanolamine therein. We studied this issue with hamster kidney cell‐line using a novel approach, i.e. electrospray mass‐spectrometry and stable isotope‐labeled precursors. Scanning for a neutral loss of 155, which is characteristic for phosphatidylisopropanolamine, indicated that this lipid is indeed present. The identity of phosphatidylisopropanolamine was supported by the following: (i) it co‐chromatographed with phosphatidylethanolamine; (ii) its molecular species profile was similar to that of phosphatidylethanolamine; (iii) its head group was labeled from 13C‐threonine; and (iv) its concentration increased in parallel with phosphatidylthreonine. Tests with solubilized decarboxylase and subcellular fractionation studies indicated that the low cellular content of phosphatidylisopropanolamine is due to inefficient decarboxylation, rather than poor translocation of phosphatidylthreonine to mitochondria. Importantly, the average hydrophobicity of phosphatidylisopropanolamine molecular species was significantly less than that of phosphatidylthreonine species, indicating that hydrophilic phosphatidylthreonine species translocate to mitochondria far more rapidly than hydrophobic ones. Parallel results were obtained for phosphatidylserine. These findings imply that efflux from the ER membrane could be the rate‐limiting step in the phosphatidylthreonine and ‐serine translocation to mitochondria.
Amphiphysins: Raising the BAR for Synaptic Vesicle Recycling and Membrane Dynamics
Authors: Zhang Bing , Zelhof Andrew C.
Published: March 2003

Amphiphysins, members of the BAR (Bin‐Amphiphysin‐Rvsp) protein super family, have been postulated to play a key role in clathrin‐mediated endocytosis of synaptic vesicles (SVs). This review focuses on recent genetic studies of the role of amphiphysins in SV recycling and membrane morphogenesis. In the mouse, brain‐specific amphiphysin I and II regulate, but are not essential for, SV recycling. The role of this regulation appears important, as mice deficient in these proteins have seizures and are deficient in learning and memory. In the fruit flyDrosophila melanogaster, amphiphysin is found in muscles and is enriched at postsynaptic membranes of neuromuscular junctions (NMJs); however, it does not play a role in SV recycling. Rather, amphiphysin in fly muscles appears to regulate the organization and structure of the muscle T‐tubule system and possibly the subsynaptic reticulum. Amphiphysin is also involved in membrane organization in both neurons and non‐neuronal cells inDrosophila. These studies reveal pleiotropic functions for amphiphysins in clathrin‐mediated endocytosis and the regulation of membrane dynamics, perhaps through the actin cytoskeleton.
Bannayan–Riley–Ruvalcaba syndrome: report of a family
Authors: Wilson PHR , MacDonald DG , Felix DH
Published: March 2003

Bannayan–Riley–Ruvalcaba (BRR) syndrome is a rare inherited condition. We describe the protean orofacial manifestations of this syndrome in one family and consider their management. The dental surgeon should be aware of this entity, its orofacial connotations and the possible association with Cowden’s syndrome.
Effect of high‐density lipoprotein on lipopolysaccharide‐induced alveolar bone resorption in rats
Authors: Jonarta AL , Pudyani PS , Sosroseno W
Published: March 2003

OBJECTIVE: To determine whether treatments with high‐density lipoprotein (HDL) may alter the lipopolysaccharide (LPS)‐induced alveolar bone resorption in rats.

MATERIALS AND METHODS: Rats were injected with 500 μg of LPS from Escherichia coli at the alveolar mucosa of lower right first molar once every 2 days for 8 days. The negative and positive control were injected with phosphate buffered saline (PBS) and LPS alone, respectively. In HDL‐treated animals various concentration of HDL were injected immediately before, after the third or the final LPS injection. The bone sections were stained with tartrate‐resistant acid phosphatase (TRAP) and the numbers of both osteoclasts and preosteoclasts and the levels of alveolar bone resorption were assessed.

RESULTS: The numbers of both osteoclasts and preosteoclasts and the levels of alveolar bone resorption in animals treated with HDL before or during LPS injections were lower than those in the positive control, but higher than those in the negative control, regardless of HDL doses. Similar results were also observed in animals treated with 250 and 500 μg of HDL after the final LPS injection. Only treatments with 1000 μg of HDL after LPS injections completely reduced the number of both osteoclasts and preosteoclasts, but only partially decreased the alveolar bone resorption.

CONCLUSION: HDL treatments partially reduced the LPS‐induced alveolar bone resorption in vivo in rats, suggesting that HDL may neutralize the ability of LPS to induce alveolar bone resorption.
Inhibitory function of secretory leukocyte proteinase inhibitor (SLPI) in human saliva is HIV‐1 specific and varies with virus tropism
Authors: Skott P , Lucht E , Ehnlund M , Björling E
Published: March 2003

OBJECTIVE: Secretory leukocyte proteinase inhibitor (SLPI) is an endogenous mucosa associated protein that has been proposed to possess anti‐human immunodeficiency virus type 1 (HIV‐1) activity. The aim of this study was to investigate the biological function of SLPI in salivary mediated inhibition of HIV infection and in addition the inhibitory effect of SLPI using isolates of varied virus tropism.

MATERIAL AND METHODS: The inhibitory effect of HIV‐1 infection in vitro, mediated by 60 different saliva samples was analyzed with respect to levels of SLPI. Salivary samples depleted from IgA and SLPI, respectively, were further analyzed for anti‐HIV activity. The antiviral effect of recombinant SLPI was investigated within an in vitro system of HIV‐1 infection of target cells using a panel of viral isolates with distinct coreceptor usage. Furthermore we tested a panel of overlapping synthetic peptides, representing the amino acids in SLPI, for their capacity to inhibit HIV‐1 infection of human peripheral blood mononuclear cells (PBMCs).

RESULTS AND CONCLUSIONS: These experiments show that elevated levels of salivary SLPI can be associated with an increased inhibitory effect of the whole saliva sample, and that this inhibitory effect is decreased with broad coreceptor usage of the virus.
Impact of lysozyme and lactoferrin on oral Candida isolates exposed to polyene antimycotics and fluconazole
Authors: Anil S , Samaranayake LP
Published: March 2003

OBJECTIVE: To assess the antifungal activity of lysozyme and lactoferrin on 10 oral isolates each of Candida albicans and Candida tropicalis following their brief exposure (1 h) to subtherapeutic concentrations of two polyene drugs – nystatin, amphotericin B, and an azole – fluconazole.

METHODS: Yeasts were sequentially exposed to subtherapeutic concentrations of antifungals and then to either lysozyme or lactoferrin and the viability evaluated by quantifying colony‐forming units.

RESULTS: The exposure of both C. albicans and C. tropicalis isolates to all three antifungal agents significantly increased their susceptibility to lysozyme (P < 0.05) but not to lactoferrin. Exposure to the two polyene drugs had a lesser impact on the lysozyme susceptibility of both Candida species compared with the azole drug. Both interspecies and intraspecies sensitivity to lysozyme was noted and C. albicans was less susceptible than C. tropicalis.

CONCLUSIONS: Lysozyme, in addition to being a potent natural antifungal agent, may act synergistically with the studied antimycotics.
Nursing Home Characteristics Associated with Tube Feeding in Advanced Cognitive Impairment
Authors: Md Susan L. Mitchell , Mph Dan K. Kiely , Gillick Muriel R.
Published: March 2003

OBJECTIVES: To identify nursing homes factors associated with the use of tube feeding in advanced cognitive impairment.

DESIGN: Descriptive study.

SETTING: The On‐line Survey Certification of Automated Records (OSCAR) was used to obtain facility characteristics from 1,057 licensed nursing homes in six states from 1995 to 1996.

PARTICIPANTS: Residents aged 65 and older with advanced cognitive impairment who had a feeding tube placed over a 1‐year period were identified using the Minimum Data Set.

MEASUREMENTS: Nursing home characteristics independently associated with feeding tube placement were determined.

RESULTS: Having a full‐time speech therapist on staff, more licensed nurses and fewer nursing assistants were independently associated with greater use of tube feeding in severely cognitively impaired residents. Other features associated with tube feeding included larger facility size, higher proportion of Medicaid beds, absence of an Alzheimer's disease unit, pressure ulcers in 10% or more of residents, and a higher proportion of residents lacking advance directives and with total functional dependency.

CONCLUSIONS: Assessment by a speech therapist, staffing ratios, advance directives, fiscal considerations, and specialized dementia units are potentially modifiable factors in nursing homes that may influence the practice of tube feeding in advanced cognitive impairment.
Does Inflammation or Undernutrition Explain the Low Cholesterol–Mortality Association in High‐Functioning Older Persons? MacArthur Studies of Successful Aging
Authors: Hu Peifeng , Seeman Teresa E. , Harris Tamara B. , Reuben David B.
Published: March 2003

OBJECTIVES: To explore the effect of inflammation and undernutrition on the association between hypocholesterolemia and higher overall mortality in high‐functioning older persons.

DESIGN: Prospective cohort study.

SETTING: Three U.S. communities.

PARTICIPANTS: A cohort of 870 participants from the MacArthur Studies of Successful Aging.

MEASUREMENTS: Baseline information was obtained for serum levels of cholesterol, C‐reactive protein, interleukin‐6, and albumin; body mass index; prevalent medical conditions; health behaviors; and medications. Crude and multivariate logistic regression analyses were used to examine the association between serum total cholesterol levels and 7‐year all‐cause mortality, while adjusting for potential confounders.

RESULTS: In univariate analysis, the risk ratio of low serum total cholesterol level (<169 mg/dL) for 7‐year total mortality was 1.90 (95% confidence interval (CI) = 1.18–3.07). The multiple adjusted risk ratios were 1.82 (95% CI = 1.10–3.00) after controlling for markers of inflammation and nutrition and 1.39 (95% CI = 0.80–2.40) after adjustment for additional cardiovascular risk factors. Sex was an important confounding variable that contributed to the observed inverse association between low serum cholesterol and overall mortality in univariate analysis.

CONCLUSIONS: Hypocholesterolemia is not an independent risk factor for increased overall mortality in high‐functioning community‐dwelling older men and women. The association between low total cholesterol and high mortality observed in crude analysis is mainly confounded by common cardiovascular risk factors, rather than underlying inflammation or undernutrition.
Assessment of the role of sphingosine 1-phosphate and its receptors in high-density lipoprotein-induced stimulation of astroglial cell function
Authors: MALCHINKHUU Enkhzol , SATO Koichi , MURAKI Takeshi , ISHIKAWA Koichi , KUWABARA Atsushi , OKAJIMA Fumikazu
Published: March 2003

It has been suggested that lipoproteins in the central nervous system are involved in the regulation of several neural functions independent of cholesterol metabolism as well as those related to lipid metabolism. We recently demonstrated that lipoproteins are carriers for sphingosine 1-phosphate (S1P). This raised the possibility that S1P mediates the neural cell functions induced by lipoproteins. In the current study, we examined the effects of plasma high-density lipoprotein (HDL) on astroglial cell functions, focusing especially on the role of the lipoprotein-associated S1P. In rat type I astrocytes or C6 glioma cells, similar to S1P, HDL stimulated DNA synthesis and mRNA expression of fibroblast growth factor-2, a potent neurotrophic factor, which was associated with the activation of extracellular signal-regulated kinase (ERK) in a pertussis toxin-sensitive manner. The data from fractionation studies of HDL indicated that S1P may be a major component for the activation of ERK. In C6 glioma cells, HDL also induced phospholipase C-dependent intracellular Ca2+ mobilization. Desensitization of the C6 glioma cells with S1P abolished these HDL-induced actions. Furthermore, overexpression of S1P receptors in C6 glioma cells led to a significant enhancement of HDL-induced ERK activation and Ca2+ mobilization. Thus, at least some HDL-induced actions may be mediated by cell-surface S1P receptors in astroglial cells. These results imply that S1P might partially mediate lipoprotein-induced cholesterol metabolism-independent neural cell functions in the central nervous system.
Oestrogen Regulates Neurofilament Expression in a Subset of Anterior Pituitary Cells of the Adult Female Rat
Authors: Fiordelisio T. , Hernández‐Cruz A.
Published: March 2003

It is the prevailing view that the neurohypophysis derives from neural crest while the pituitary's anterior lobe is of ectodermal origin. However, it has been recently suggested that anterior pituitary cells could have in part neuro‐ectodermal origin, and thus should express specific neuronal markers. This issue was examined previously with conflicting results. The present study attempts to clarify the question of whether or not neuronal markers are expressed in the adenohypophysis. Using quantitative immunofluorescence, we have positively identified a subset of anterior pituitary cells, which express immunoreactivity for neuronal markers, including 68 kDa neurofilament (NF68). Interestingly, we noticed that the expression of NF68 is sexually dimorphic (i.e. neurofilament‐positive cells are more abundant in sexually mature female rats). In addition, NF68 expression in female rats increases during ontogenic development and reaches a plateau level after puberty. Thereafter, it displays plastic changes along the oestrous cycle, with the maximum of neurofilament expression at oestrus and the minimum at proestrus. NF68 immunoreactivity was examined after ovariectomy, oestradiol replacement and treatment with an specific oestrogen receptor antagonist. Bilateral ovariectomy induced a significant reduction in the number of NF68‐positive cells. This effect was completely prevented by treatment of ovariectomized rats with oestradiol. When intact female rats were treated with the anti‐oestrogen tamoxifen, a drastic decrease in NF68 expression in anterior pituitary cells was observed. Furthermore, oestradiol administration in castrated male rats increased NF68 immunoreactivity. Double‐immunolabelling experiments provided evidence that pituitary cells expressing neuronal traits correspond to subsets of lactotrophs, somatotrophs, thyrotrophs and gonadotrophs. It remains to be established if NF68 induction in the pituitary is due to direct and/or indirect effects of oestrogens. Also, the possible functional role of this subset of NF68‐positive anterior pituitary cells in the female rat remains to be examined.
Growth and dry‐mass partitioning in tomato as affected by phosphorus nutrition and light
Authors: De Groot C. C. , Marcelis L. F. M. , Van Den Boogaard R. , Lambers H.
Published: March 2003

We studied the effects of phosphorus (P) and light on the physiological and morphological components of growth of young tomato plants (Lycopersicon esculentum Mill. cv. Capita). The importance of dry‐mass partitioning and starch accumulation in explaining the effects of P limitation on growth was examined more closely. Plants were grown at a wide range of exponential P supply rates (between 70 and 320 mg g−1 d−1) and one free‐access treatment (1 mm). Two light levels (70 and 300 µmol m−2 s−1) were applied. Growth response coefficients (GRCs) were calculated to address the importance of different growth parameters in explaining relative growth rate (RGR). At both light levels, net assimilation rate (NAR) was more important than leaf area ratio (LAR) in explaining the effects of P on growth as indicated by GRCs. At less severe P limitation, LAR became more important and NAR less important. Dry‐mass partitioning to both roots and leaves played a minor role in determining the effects of P limitation on growth as indicated by low GRCs. The increase in starch at mild P limitation showed that the assimilate supply was not limiting. At severe P limitation, the rate of photosynthesis was decreased, as suggested by the decrease in starch accumulation.
Nocturnally retained zeaxanthin does not remain engaged in a state primed for energy dissipation during the summer in two Yucca species growing in the Mojave Desert
Authors: Barker D. H. , Adams W. W. , Demmig‐Adams B. , Logan B. A. , Verhoeven A. S. , Smith S. D.
Published: March 2003

Differently oriented leaves of Yucca schidigera and Yucca brevifolia were characterized in the Mojave Desert with respect to photosystem II and xanthophyll cycle activity during three different seasons, including the hot and dry summer, the relatively cold winter, and the mild spring season. Photosynthetic utilization of a high percentage of the light absorbed in PSII was observed in all leaves only during the spring, whereas very high levels of photoprotective, thermal energy dissipation were employed both in the summer and the winter season in all exposed leaves of both species. Both during the summer and the winter season, when energy dissipation levels were high diurnally, xanthophyll cycle pools (relative to either Chl or other carotenoids) were higher relative to the spring, and a nocturnal retention of high levels of zeaxanthin and antheraxanthin (Z + A) occurred in all exposed leaves of both species. Although this nocturnal retention of Z + A was associated with nocturnal maintenance of a low PSII efficiency (Fv/Fm) on a cold winter night, pre‐dawn Fv/Fm was high in (Z + A)‐retaining leaves following a warm summer night. This indicates nocturnal engagement of Z + A in a state primed for energy dissipation throughout the cold winter night – while high levels of retained Z + A were not engaged for energy dissipation prior to sunrise on a warm summer morning. Possible mechanisms for a lack of sustained engagement of retained Z + A for energy dissipation at elevated temperatures are discussed.
Dark‐bellied Brent Geese Branta bernicla bernicla, as recorded by satellite telemetry, do not minimize flight distance during spring migration
Authors: Green Martin , Alerstam Thomas , Clausen Preben , Drent Rudi , Ebbinge Barwolt S.
Published: March 2003

Nine Dark‐bellied Brent Geese Branta bernicla bernicla were equipped with satellite transmitters during spring staging in the Dutch Wadden Sea in 1998 and 1999. The transmitters (in all cases less than 3% of body mass) were attached to the back by a flexible elastic harness. One juvenile female was tracked to the Yamal peninsula in 1998. Eight adult males were selected from a single catch of 75 to span the range of body mass observed on the date of capture (11 May 1999) and all but the lightest individual completed the first lap of the migratory flight to the White Sea, Russia, according to the time schedule normal for the species. Six birds were successfully tracked to Taymyr for a total distance averaging 5004 km (range 4577–5164) but judging from later movements none bred (although 1999 was a breeding year). Although the routes chosen during spring migration were closely similar, none of the tagged birds migrated together. On average the geese used 16 flights to reach their summer destinations on Taymyr. The longest uninterrupted flights during the first half of the journey (Wadden Sea to Kanin) covered 1056 km (mean of seven adult males, range 768–1331), while the corresponding value for the second half of the migration (Kanin–Taymyr) was only 555 km (mean of six adult males). Only 7% of total time during spring migration was spent in active flight, as contrasted to c. 80% at long‐term stopovers. Overall average travelling speed was 118 km/day (range 97–148). Including fattening prior to departure the rate of travel falls to 62 km/day (range 49–70), in keeping with theoretical predictions. Routes followed deviated from the great circle route, adding at least 700 km (16%) to the journey from Wadden Sea to Taymyr, and we conclude that the coastal route is chosen to facilitate feeding, drinking and resting en route instead of minimizing total flight distance.
Influence of CD4 T cells and the source of major histocompatibility complex class II‐restricted peptides on cytotoxic T‐cell priming by dendritic cells
Authors: Faiola Brenda , Doyle Carolyn , Gilboa Eli , Nair Smita
Published: March 2003

We have previously reported that bone marrow derived dendritic cells (DC) pulsed with major histocompatibility complex (MHC) class I‐restricted peptide efficiently prime a cytotoxic T lymphocyte (CTL) response in vivo. Here we assess the involvement of CD4+ T cells in the induction of CD8+ CTL by DC by testing the ability of class II‐deficient (C2D) DC, class II mutant (Αβmut) DC and autologous serum generated DC (AS DC) to present class I‐restricted antigens in vitro and in vivo. DC generated from the bone marrow of class II knockout mice and transgenic mice expressing a mutant class II that can not bind CD4 were phenotypically similar to wild type (wt) DC, except with regard to MHC class II expression. The C2D and Αβmut DC, though fully capable of presenting the class I‐restricted ovalbumin (OVA) peptide to a T‐cell hybridoma in vitro, failed to prime a CTL response in vivo. Restoration of class II expression on C2D DC allowed priming of a CTL response; thus, the defect in CTL priming was indeed caused by the absence of class II expression. Likewise, DC generated in autologous serum were unable to prime a CTL response as these DC only express ‘self’ class II epitopes and therefore would not activate syngeneic CD4+ T cells. Addition of exogenous class II epitopes rescued the ability of AS DC to prime a CTL response. These observations provide convincing evidence that efficient CTL induction by DC in vivo requires concomitant presentation of class II epitopes for CD4+ T‐cell induction.
Murine graft‐versus‐host disease induced using interferon‐γ‐deficient grafts features antibodies to double‐stranded DNA, T helper 2‐type cytokines and hypereosinophilia
Authors: Ellison Cynthia A. , Bradley David S. , Fischer Jacqie M. M. , Hayglass Kent T. , Gartner John G.
Published: March 2003

Acute, lethal graft‐versus‐host disease (GvHD) develops in B6D2F1 hybrid recipients of wild‐type, C57BL/6, parental strain grafts; however, when interferon‐γ (IFN‐γ) gene knockout (gko) donors are used, the disease is prolonged and associated with a higher level of engraftment, particularly of T cells. Lesions containing large, mixed cellular infiltrates develop in the skin, liver, pancreas, salivary gland, lung and kidney. In our current study, we wished to determine whether GvHD features a preponderance of T helper 2 (Th2) cytokines in the absence of donor‐derived IFN‐γ, and whether autoantibody production, commonly associated with chronic GvHD, also occurs. Because mitogen responsiveness is consistently suppressed in mice with acute GvHD, we wished to measure this response in recipients of IFN‐γ gko grafts. Our findings indicate that spleen cells from the latter produce interleukin (IL)‐4, IL‐5 and IL‐13 in culture, but respond poorly to concanavalin A (Con A) and lipopolysaccharide (LPS). Their sera contain anti‐nuclear antibodies (ANA), some of which are specific for double‐stranded (ds)DNA and are predominantly immunoglobulin (Ig)M and IgG1. We also noted the presence of numerous eosinophils in the infiltrates developing within the target organs. In some respects, this syndrome bears resemblance to both systemic lupus erythematosus (SLE) and chronic GvHD. However, histological evidence of glomerulonephritis is lacking and proteinuria fails to develop in recipients of IFN‐γ gko grafts, suggesting that IFN‐γ may be necessary for the development of lupus nephritis. On a broader scope, our findings underscore the importance of IFN‐γ in the pathogenetic mechanism of GvHD, and demonstrate that the absence of this cytokine promotes the development of chronic GvHD and autoimmunity.
Big endothelin‐1 but not endothelin‐1 is present in the smooth muscle stroma of the prostate gland of the rat
Authors: Ventura S. , Salamoussa A.
Published: March 2003

Immunohistochemical techniques were employed to localize the presence of endothelins in the mature rat prostate gland. Immunoreactivity for big endothelin‐1 but not endothelin‐1 was observed in the fibromuscular stroma of the rat prostate gland. No immunoreactivity was seen in the glandular epithelium. Double staining procedures showed big endothelin‐1 immunoreactivity to be co‐localized with α‐actin immunoreactivity. The stroma of the prostate gland also contained nerve fibres coursing through it which are immunopositive for tyrosine hydroxylase. These results suggest that big endothelin‐1 but not endothelin‐1 is co‐localized with α‐actin in the smooth muscle cells of the rat prostate gland. This implies that endothelin‐1 is synthesized on demand from big endothelin‐1 in the fibromuscular stroma of the rat prostate.
Phagocytic capacity of leucocytes in sheep mammary secretions following weaning
Authors: Tatarczuch Liliana , Bischof Robert J. , Philip Christopher J. , Lee Chee‐Seong
Published: March 2003

Lactating animals are particularly susceptible to mastitis during the early stages of mammary gland involution following weaning. In this study we compared the phagocytic capacity of cells collected from sheep mammary secretions at different stages of involution. The ability of neutrophils and macrophages to ingest latex beads in anin vitrophagocytosis assay was found to be dependent on how heavily the phagocytes were loaded with milk constituents. There was a decline in the phagocytic capacity of neutrophils from 1 to 2 days after weaning, while macrophages collected from fully involuted glands were more effective phagocytes compared with earlier stages (7–15 days) of involution. In addition, dendritic cells present in fully involuted mammary gland secretions (30 days after weaning) were highly phagocytic. These studies demonstrate that neutrophils and macrophages in sheep mammary secretions at early stages of involution are incapacitated, and as such may compromise the immune status of the mammary gland.
Density‐dependent starvation in a vertebrate without significant depletion
Authors: Goss‐Custard J.D. , West A.D. , Stillman R.A. , Durell S.E.A. LE V. DIT , Caldow R.W.G. , McGrorty S. , Nagarajan R.
Published: March 2003

It is often difficult to quantify the separate contribution of exploitation and interference competition to the starvation of poor competitors yet, in vertebrates, it seems widely supposed that depletion is normally the mechanism underlying density‐dependent starvation. This paper presents arguments that density‐dependent starvation occurs through interference in wintering oystercatchersHaematopus ostraleguseating musselsMytilus eduliswithout prey depletion having a significant influence.

Exclosure experiments and mussel bed surveys showed that oystercatchers (i) depleted mussel numerical density by up to 25% in their most preferred large prey size classes, but by only 12·1% overall; (ii) reduced mean mussel length by 1·5%; but (iii) had no detectable effect on the thickness of the shells and therefore the availability of mussels to the 60% of oystercatchers that opened mussels by breaking the shell.

Oystercatcher intake rate did not fall until prey biomass had decreased to very low densities. Depletion was not nearly large enough for mussel biomass to be reduced to this point.

The flesh content of individual mussels decreased from autumn to spring by 40–50% but oystercatchers did not increase their rate of foraging to compensate. Intake rate declined over the winter because of deteriorating mussel condition; very little was because of depletion.

Over the current range of population size, the density‐dependent functions produced by a behaviour‐based individual’s model were the same whether depletion was allowed to occur or not, confirming that depletion played no role in the density‐dependent starvation.

At current population sizes, intake rate was reduced as population density increased only through increased interference, this leading to starvation late in winter when mussel flesh content was low. It was not just the subdominant birds most susceptible to interference that starved, but the least efficient ones as well, even though the density dependence was not due to exploitation competition.
Ecosystem structure and productivity of tropical rain forests along altitudinal gradients with contrasting soil phosphorus pools on Mount Kinabalu, Borneo
Authors: Kitayama Kanehiro , Aiba Shin‐Ichiro
Published: March 2003

We measured above‐ground net primary productivity (ANPP) and ecosystem structure and processes in eight rain forest stands at four elevations (700, 1700, 2700 and 3100 m) and on two geological substrates (sedimentary vs. ultrabasic rock) on Mount Kinabalu, Borneo.

All ultrabasic sites had smaller pools of total soil phosphorus (P) and of labile inorganic P than did the sedimentary sites at the same altitudes. We predicted that the magnitude of altitudinal changes in ANPP would be less on ultrabasic than on sedimentary substrates, reflecting lower temperature dependency of ANPP under stronger P limitation.

Although ANPP declined with increasing altitude on both substrates, the slopes of the two regression lines were similar. The intercept was, however, marginally greater on sedimentary than on ultrabasic substrate.

Stand‐level nutrient‐use efficiencies (the ratio of litterfall mass to nutrient return) for N and P were only affected by altitude on ultrabasic substrate where they increased exponentially. Mean foliar N and P contents per unit leaf area of the canopy species increased with altitude on both substrates, but differed between substrates at the same altitude only for P (lower on ultrabasic).

Leaf area index (LAI) decreased upslope on both substrates. We assumed that half of primary production was allocated below‐ground in order to evaluate stand level net assimilation rate (NAR). This was nearly constant on sedimentary substrate, but declined linearly with increasing altitude on ultrabasic substrate, where it may have to be added to LAI to explain ANPP patterns.

We suggest that on sedimentary substrate trees may be able to maintain NAR under colder environments by increasing foliar N and P per unit leaf area, but P deficiency prevents them from adjusting on ultrabasic substrate.
Clonal variation in the thermal response of the submerged aquatic macrophyte Potamogeton pectinatus
Authors: Pilon Jörn , Santamaría Luis
Published: March 2003

Broadly distributed plants have to cope with dramatic differences across latitude in the prevailing environmental temperature. We investigated the effect of water temperature on plant morphology, biomass accumulation and oxygen‐exchange for five clones of the submerged aquatic macrophyte Potamogeton pectinatus L., originating from 42 to 68°N.

We tested whether P. pectinatus clones show local adaptation to the prevailing environmental temperatures (in which case high‐latitude clones would perform better at lower temperatures and vice versa). Alternatively, pronounced phenotypic plasticity in the response to temperature could enable individual clones to perform well over a wide range of environmental temperatures (i.e. high degree of thermal tolerance).

The overall pattern of thermal response was similar for all clones. In addition, we detected acclimative phenotypic plasticity in both physiological and morphological plant parameters. The optimum temperatures for gross or for net photosynthesis did not vary with growth temperature, but morphological acclimation partly compensated for the loss of photosynthetic capacity at higher temperatures, enabling comparable rates of ambient gross photosynthesis. Respiratory reactions also showed some degree of thermal acclimation to higher temperatures.

As a result of the combined effects of changes in morphology and physiology, all clones produced similar amounts of plant biomass over a relatively wide range of water temperatures. We therefore conclude that P. pectinatus is thermally tolerant and not locally adapted.
New imaging modes for lenslet‐array tandem scanning microscopes
Authors: Watson T. F. , Jus̆kaitis R. , Wilson T.
Published: March 2003

The tandem scanning microscope permits confocal images to be obtained in real time and viewed directly by eye. The light budget of these instruments may be increased from a few percent to a few tens of percent by incorporating an array of microlenses so as to increase the amount of illumination light that reaches the specimen. These instruments are configured for fluorescence imaging together with laser illumination. We describe how the versatility of the instrument may be enhanced to permit the use of incoherent light sources as well as extending the imaging modes to include bright‐field reflection.
Expression and regulation of corticotropin‐releasing hormone binding protein (CRH‐BP) in rat adrenals
Authors: Chatzaki E. , Margioris A. N. , Gravanis A.
Published: March 2003

Corticotropin‐releasing hormone (CRH) is present in the adrenal gland acting as a paracrine factor via stimulation of the locally expressed CRH receptors. In this study, we examined if the adrenal CRH system also contains a key component of the neuronal CRH‐containing system, the CRH‐binding protein (CRH‐BP). Our data show that: (i) the CRH‐BP transcript is detectable using RT‐PCR in total RNA isolated from rat adrenals, and (ii) its protein product is also found by western blot analysis in cell lysates. (iii) Immunohistochemical staining showed that adrenomedullary chromaffin cells produce the bulk of adrenal CRH‐BP, an ability retained by the PC12 rat pheochromocytoma cell line. (iv) Regulation of adrenal CRH‐BP expression by major modulators of the CRH system was also examined. Protein expression appears to be under the positive control of CRH itself, protein kinase A effector cAMP, glucocorticoids and interleukin (IL)‐6. It is thus evident that CRH‐BP may play a role in mediating their effects in the adrenal. (v) Differentiation of PC12 into neuron‐like cells resulted in a significant increase in CRH‐BP, parallel to the induction of the CRH peptide itself. In conclusion, CRH‐BP mRNA and protein are present in normal rat adrenomedullary chromaffin cells and in the PC12 rat pheochromocytoma cell line, making the adrenal CRH system directly comparable with those described in the CNS.
Phosphatidylinositol 3‐kinase is a central mediator of NMDA receptor signalling to MAP kinase (Erk1/2), Akt/PKB and CREB in striatal neurones
Authors: Perkinton Michael S. , Ip James , Wood Gemma L. , Crossthwaite Andrew J. , Williams Robert J.
Published: March 2003

Ca2+influx through NMDA receptors can initiate molecular changes in neurones which may underlie synaptic plasticity, neuronal development, survival and excitotoxicity. Signalling through the MAP kinase (Erk1/2) cascade may be central to␣these processes. We previously demonstrated that Ca2+‐permeable AMPA receptors activate Erk1/2 through a phosphatidylinositol 3‐kinase (PI 3‐kinase)‐dependent mechanism. We now report that NMDA receptor activation of Erk1/2 was also blocked by inhibitors of PI 3‐kinase (LY 294002, wortmannin). In addition, pre‐treatment of neurones with pertussis toxin inhibited NMDA‐induced Erk1/2 activation, indicating a role for heterotrimeric Gi/oproteins. PI 3‐kinase directs activation of the serine‐threonine kinase Akt (PKB). Treatment of striatal neurones with glutamate induced a rapid Ca2+‐dependent and PI 3‐kinase‐dependent phosphorylation of Akt (Ser473), which was not blocked by the Mek inhibitors PD98059 or U0126. Targets for Erk1/2 and Akt pathways include transcription factors. Glutamate‐induced phosphorylation of cAMP response element binding protein (CREB; Ser133) was partially blocked with either PD98059, U0126, LY294002 or wortmannin but was very strongly inhibited on co‐application of LY294002 and PD98059. We propose that NMDA receptor stimulation can activate Erk1/2 and Akt signalling pathways in a PI 3‐kinase dependent manner which may target CREB in the nucleus.