bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence For The Existence Of A Constitutive Nitric Oxide Synthase In Vascular Smooth Muscle
Authors: Cheah LS , Gwee MCE , Das R , Ballard H , Yang YF , Daniel EE , Kwan CY
Published: March 2003

1. We have identified a neuronal nitric oxide synthase (NOS)‐like constitutive form of NOS in vascular smooth muscle (VSM) using a functional contractility approach as well as immunohistochemical methods.

2. NG‐Nitro‐L‐arginine methyl ester, NG‐monomethyl‐L‐ arginine and NG‐nitro‐L‐arginine (L‐NOARG), the competitive inhibitors of NOS, inhibited Mg2+‐induced relaxation of de‐endothelialized rat aorta precontracted with phenylephrine (PE). This Mg2+ relaxation of VSM was not affected by inhibitors of inducible NOS.

3. Electrical field stimulation (EFS; 30–70 Hz) caused relaxation of rat aorta in the presence of tetrodotoxin (therefore not a neurogenic effect) and this EFS relaxation was effectively inhibited by L‐NOARG, oxyhemoglobin and methylene blue.

4. Immunohistochemical studies of dog saphenous vein using antibodies raised against neuronal NOS indicated prominent staining along the plasmalemma in a punctate pattern similar to the distribution of antibodies against caveolin‐1, a major constituent of the plasmalemmal caveolae.

5. We propose that a constitutive NOS of non‐endothelial, non‐neuronal origin is present in a special caveolae domain of VSM cell membranes and could be activated by an ionic mechanism yet to be characterized.
Heterogeneous Distribution Of β‐Adrenoceptors and Muscarinic Receptors In The Sinoatrial Node And Right Atrium Of The Dog
Authors: Kurogouchi Fumio , Nakane Tokio , Furukawa Yasuyuki , Hirose Masamichi , Inada Yoichi , Chiba Shigetoshi
Published: March 2003

1. The pacemaker site is known to shift away from the sinoatrial (SA) node in response to autonomic stimuli.

2. To test whether the shifting of the impulse‐initiation site that occurs during autonomic nerve stimulation can be explained by the spatial distributions of β‐adrenoceptor and muscarinic receptors, we obtained densities (Bmax) and dissociation constants (Kd) for these receptors in three regions along the sulcus terminalis (the SA node itself and regions superior and inferior to it) and a region of the right atrial appendage in the dog.

3. The Bmax values for [125I]‐iodocyanopindolol binding to β‐adrenoceptors were not different among the four regions. The Bmax value for [3H]‐quinuclidinyl benzilate binding to muscarinic receptors was significantly higher in the SA node area than in any other region (P < 0.01), although there was no difference among the other three regions.

4. For each receptor, Kd values were similar among the four regions.

5. These results suggest that spatial variations in the densities of β‐adrenoceptors and muscarinic receptors are not important for shifting the impulse‐initiation site and that other factors, such as non‐uniform innervation by autonomic nerve fibres, may be mainly responsible for the pacemaker shift induced by autonomic nerve stimulation.
Effect Of Glycerol On Endothelium‐Derived Factors In The Vasculature Of The Rabbit Kidney
Authors: Sipahi Emine Y , Keskil Zuhal A , Erdinç Meral , Nergis Yusuf , Türker R Kazlm , Ercan Z Sevim
Published: March 2003

1. In the present study, endothelium‐derived relaxing factor (EDRF/nitric oxide (NO)), conversion of big endothelin (ET)‐1 to endothelin‐1 (ET‐1) and the role of reactive oxygen species were investigated in kidneys isolated from glycerol (GLY)‐pretreated rabbits.

2. Acetylcholine (ACh)‐induced vasodilation that is due to the release of EDRF/NO is significantly decreased, whereas big ET‐1‐induced vasoconstriction was increased in kidneys isolated from GLY‐pretreated rabbits.

3. Pretreatment of rabbits with the xanthine oxidase inhibitor allopurinol and the NO precursor L‐arginine reversed the inhibition of ACh‐induced vasodilation due to GLY and protects the kidney vasculature.

4. Big ET‐1, but not ET‐1, responses were found to be significantly increased in kidneys isolated from GLY‐pretreated rabbits. This increase is attributed to the higher conversion rate of big ET‐1 to ET‐1 because the ET‐converting enzyme (ECE) inhibitor phosphoramidon, at a concentration of 10–6 mol/L, causes an inhibition in the response to big ET‐1 by 52.6% in normal kidneys, whereas this inhibition with the same concentration of phosphoramidon was found to be significantly decreased in kidneys isolated from GLY‐pretreated rabbits.

5. The non‐selective NO synthase inhibitor NG‐nitro‐L‐ arginine methyl ester (L‐NAME) caused a significant potentiation in the vasoconstrictor response to ET‐1 in normal isolated perfused rabbit kidneys. However, L‐NAME did not alter the responses to ET‐1 in GLY‐pretreated kidneys.

6. These results indicate that accumulation of reactive oxygen species causes an inhibition in NO bioavailability. Increased conversion of big ET‐1 to ET‐1 may also contribute to the mechanism of vascular damage due to GLY.
Cyclosporine A protects against apoptosis in ischaemic/reperfused rat kidneys
Authors: Zhu Tongyu , Au‐Yeung Kathy KW , Siow Yaw L , Wang Guoping , O Karmin
Published: March 2003

1. Renal ischaemia followed by reperfusion leads to acute renal failure in both native kidneys and renal allografts. Cyclosporine A (CsA) has been used as an immunosuppressive agent in organ transplantation. In the present study, the effect of CsA on ischaemia/reperfusion‐induced apoptosis in the kidney was investigated.

2. Ischaemia/reperfusion injury caused widespread apoptosis primarily in the medulla of the kidney. At 1.5 mg/kg per day, CsA significantly reduced the number of apoptotic cells in rat kidney after ischaemia/reperfusion injury.

3. Low‐dose CsA treatment did not affect the levels of creatinine in the serum of rats after ischaemia/reperfusion injury.
Ageing blunts the effects of nitric oxide on myocardial O2 consumption
Authors: Weiss Harvey R , Lazar Michael J , Tse James , Scholz Peter M
Published: March 2003

1. In the present study, we tested the hypothesis that the negative myocardial metabolic effects of nitric oxide (NO) were reduced in old hearts.

2. Studies were conducted in 17 young (approximately 6 months) and 18 old (> 36 months) New Zealand anaesthetized open‐chest rabbits. Either vehicle or s‐nitroso‐N‐acetylpenicillamine (SNAP; 10−4 mol/L; a NO donor) was applied to the epicardial surface of the left ventricle. Coronary blood flow (microspheres) and artero–venous (a‐v) O2 difference (microspectrophotometry) were used to determine subepicardial (EPI) and subendocardial (ENDO) O2 consumption. Wall thickening was determined ultrasonically. Cyclic GMP and guanylyl cyclase activity were also determined. Myocardial a‐v O2 difference, flow, O2 consumption and wall thickening were comparable in young and old hearts.

3. The EPI and ENDO O2 consumption of SNAP‐treated young hearts decreased significantly (> 25%) compared with vehicle (saline). However, SNAP had no significant effects on the O2 consumption of old hearts. In addition, SNAP decreased the percentage wall thickening in young (from 18.0 ± 1.7 to 13.4 ± 1.6%), but not old (from 14.5 ± 0.9 to 11.4 ± 1.6%), hearts. Basal cGMP levels in old hearts were greater (approximately 70%) than those in young hearts (15.7 ± 2.0 vs 9.0 ± 0.8 pmol/g, EPI). s‐Nitroso‐N‐acetylpenicillamine increased cGMP in EPI (13.7 ± 1.8 pmol/g) and ENDO of young, but not old (18.7 ± 2.3 pmol/g, EPI), hearts. Similar results were also obtained using another NO donor, namely sodium nitroprusside (SNP; 10−4 mol/L). Guanylyl cyclase activity was elevated in old rabbit hearts with 0.5 mmol/L SNP (131 ± 12 vs 80 ± 12 pmol/min per mg protein for old and young rabbits, respectively).

4. Thus, while older hearts had similar O2 consumption and wall thickening compared with young hearts, they responded less well to NO and had significantly elevated basal levels of myocardial cGMP.
Renal function in adult rats subjected to prenatal dexamethasone*
Authors: Martins João PC , Monteiro Josélia C , Paixão Ana DO
Published: March 2003

1. Prenatal dexamethasone leads to low birth weight and compromises organogenesis, but its effects on nephrogenesis in male and female rats have not yet been investigated extensively. Reduced renal mass may be responsible for hypertension and renal haemodynamic and morphological adjustments to maintain the glomerular filtration rate (GFR). Subsequently, these compensatory mechanisms determine glomerular sclerosis and irreversible reduction in GFR. When a high‐protein diet is associated with reduced renal mass, it accelerates glomerular sclerosis and the decline in renal function. The aim of the present study was to evaluate whether rats subjected to prenatal dexamethasone and a high‐protein diet during growth present a premature decline in renal function.

2. The number of nephrons and renal haemodynamics were estimated in Wistar rats fed a high‐protein diet (40% protein) after weaning in offspring of dams treated with either dexamethasone (0.1 mg/kg per day) or its vehicle (control; physiological solution, 0.1 mL/kg per day) during gestation.

3. At 70 days of age, rat offspring were anaesthetized and prepared surgically for renal haemodynamic measurements.

4. Mean arterial pressure (MAP), renal blood flow (RBF) and GFR were measured using a blood pressure transducer, a flow probe and inulin clearance, respectively.

5. The number of nephrons was counted using the acid‐maceration technique.

6. Dexamethasone during pregnancy induced a lower weight gain in the dams (65%; P < 0.0001) and a lower birth weight in both male and female offspring (14 and 13%, respectively; P < 0.01).

7. Compared with control, the number of nephrons in male rats was reduced by 13% (30 703 ± 1262 vs 26 308 ± 1305, respectively; P < 0.05), but was unaltered in female rats (23 197 ± 553 vs 24 231 ± 1009, respectively).

8. Male and female rats did not show any alteration in MAP. In addition, they did not show any alteration in renal vascular resistance, RBF, filtration fraction or GFR.

9. In conclusion, prenatally administered dexamethasone (0.1 mg/kg during the entire pregnancy) induced a low birth weight. The magnitude of the reduction in nephrogenesis in male offspring from mothers treated with dexamethasone was not sufficient to alter renal function (measured at 70 days), even when rats had been fed a high‐protein diet.
Extracellular Ca2+ is obligatory for ouabain‐induced potentiation of cardiac basal energy expenditure
Authors: Guild S‐J , Ward M‐L , Cooper PJ , Hanley PJ , Loiselle DS
Published: March 2003

1. The method of action of cardiac glycosides is commonly explained by the ‘pump‐inhibition hypothesis’: inhibition of the Na+/K+‐ATPase allows [Na+]i to rise, eventually reversing Na+/Ca2+ exchange. The resulting influx of Ca2+o increases [Ca2+]i, thereby activating intracellular Ca2+‐dependent ATPases and, hence, energy demand. This sequence has been presumed to occur during diastole as well as systole. However, it has been reported that dihydro‐ouabain‐induced potentiation of heat production by quiescent ventricular trabeculae persists in the absence of Ca2+o. This implies that the pump‐inhibition hypothesis is inapplicable during diastole.

2. We tested this implication by: (i) measuring the rate of oxygen consumption (Vo2) of arrested guinea‐pig whole‐hearts; (ii) measuring[Ca2+]i in quiescent ventricular trabeculae; and (iii) mathematical modelling using software (Oxsoft Heart, Oxford Software, Oxford, UK) based on DiFrancesco‐Noble formalism.

3. Upon induction of arrest, whole heart Vo2 fell to one‐quarter of its ‘beating’ value. Subsequent perfusion with ouabain (20 µmol/L), in the presence of Ca2+o, increased Vo2 fourfold. This increase was prevented by withholding Ca2+o. Comparable results were obtained in quiescent trabeculae: ouabain increased [Ca2+]i only if Ca2+o was present. Mathematical modelling readily simulated these experimental results.

4. We conclude that influx of Ca2+o is mandatory for potentiation of cardiac basal metabolism by cardiac glycosides.
Effects of five commonly used glucocorticoids on haemangioma in vitro¶
Authors: Hasan Q , Tan ST , Xu B , Davis PF
Published: March 2003

1. High‐dose systemic or intralesional steroids are the first‐line pharmacological treatments for haemangioma. However, the mechanism of action of steroids is unknown. Using the in vitro model developed by us, the present study examined some of the effects of five commonly used glucocorticoids on haemangioma biopsies taken from two patients.

2. At 12 µmol/L, triamcinolone and dexamethasone consistently exhibited capillary growth inhibition, whereas methylprednisolone displayed an inhibitory effect during the first 7 days of culture. At this concentration, inhibition of capillary growth was observed in betamethasone‐treated cultures derived from one patient but not in those derived from the other. However, hydrocortisone had a negligible effect on capillary growth.

3. Transcription of various factors considered important for haemangioma development were studied by reverse transcription–polymerase chain reaction. Neither vascular endothelial growth factor nor fibroblast growth factor‐2 played a vital role in steroid‐induced inhibition of capillary growth. All glucocorticoids induced a marked decrease of interleukin (IL)‐6 transcripts.

4. Capillary growth inhibition in cultures treated with all glucocorticoids, except triamcinolone, was associated with an increased transcription of clusterin/apolipoprotein J (clust/apoJ), an apoptotic gene. There was increased transcription of mitochondrial cytochrome (cyt) b in the inhibited cultures resulting from triamcinolone, dexamethasone or methylprednisolone treatment that was associated with capillary growth inhibition, suggesting an important role of mitochondria in glucocorticoid‐induced regression of haemangioma.

5. Our results indicate that glucocorticoids may modulate haemangiogenesis via an upregulation of cyt b, clust/apoJ and/or IL‐6. The variable effects of different glucocorticoids on one or more of these factors may explain the interindividual variation in the in vivo response of haemangioma to the steroids.
Protein tyrosine kinase‐dependent release of intracellular calcium in the sea urchin egg
Authors: Shen Sheldon S. , Kinsey William H. , Lee Shyh‐Jye
Published: March 2003

The aminoguanide, methylglyoxal bis(guanylhydrazone) (MGBG), was shown to stimulate phosphorylation of RR‐SRC, a synthetic protein tyrosine kinase (PTK) substrate, and different levels of tyrosyl phosphorylation of endogenous proteins in a sea urchin egg membrane‐cortex preparation. Stimulating protein tyrosine kinase activity in the sea urchin egg stimulated intracellular Ca2+ release, because microinjection of 1–5 mM of MGBG into unfertilized eggs triggered a transient rise in intracellular Ca2+ activity ([Ca2+]i) after a brief latent period. Pretreating eggs with PTK‐specific inhibitors, genistein or tyrphostin B42+, significantly inhibited the MGBG‐induced rise in [Ca2+]i. Methylglyoxal bis(guanylhydrazone) stimulation of PTK activities in the unfertilized sea urchin egg appeared to trigger Ca2+ release through phospholipase C (PLC)‐dependent inositol 1,4,5‐trisphosphate (InsP3) production. The MGBG‐induced Ca2+ response could be suppressed in eggs preloaded with the InsP3 receptor antagonist, heparin, and was reduced in eggs pretreated with U7312+, a PLC inhibitor. However, the response was unchanged in eggs treated with nicotinamide, an inhibitor of ADP‐ribosyl cyclase, or nifedipine, an inhibitor of nicotinic acid adenine dinucleotide phosphate activity. These results suggest that MGBG may be useful as a chemical agonist of PTK in sea urchin eggs and allow direct testing of the PTK requirement for the transient rise in [Ca2+]i in sea urchin eggs during fertilization. Although genistein was observed to significantly delay the onset, the sperm‐induced Ca2+ response in PTK inhibitor‐loaded eggs otherwise appeared normal. Therefore, it was concluded that sea urchin eggs contain a PTK‐dependent pathway that can mediate intracellular Ca2+ release, but PTK activity does not appear to be required for the fertilization response.
Functional retinoid receptors in budding ascidians
Authors: Kamimura Mika , Fujiwara Shigeki , Kawamura Kazuo , Yubisui Toshitsugu
Published: March 2003

A homolog of retinoid X receptors (RXR), named PmRXR, was cloned from the budding ascidian, Polyandrocarpa misakiensis. Gel‐shift assays revealed that PmRXR and a previously identified P. misakiensis retinoic acid receptor (PmRAR) formed a complex to bind vertebrate‐type retinoic acid response element (RARE). Transfection assays were carried out using a reporter gene containing a RARE upstream of lacZ. Two chimeric effector genes were constructed by placing PmRXR and PmRAR cDNA fragments (containing the DNA‐binding, ligand‐binding and ligand‐dependent transactivation domains) downstream of the human RXRα and RARα cDNA (covering the N‐terminal coding region), respectively. Each chimeric cDNA was ligated to a notochord‐specific enhancer. In case the embryos were transfected with all three transgenes and treated with retinoic acid (RA), the reporter gene was activated in the notochord cells. The result suggests that the PmRXR/PmRAR complex functions as an RA‐dependent transcriptional activator. The PmRXR mRNA was detected in a mesenchymal cell type, called glomerulocyte, in the developing Polyandrocarpa bud. As this cell type has been shown to express PmRAR mRNA, it seems possible that the PmRXR/PmRAR complex mediates RA signaling in this cell type to induce the expression of genes involved in the morphogenesis of the developing bud.
Appearance of hair follicle‐inducible mesenchymal cells in the rat embryo
Authors: Osada Aki , Kobayashi Koji
Published: March 2003

Rat vibrissa follicle morphogenesis starts around 13 days of gestation. By day 14 mesenchymal cells have already aggregated as ‘condensations’ beneath the initial hair bud. Some of the mesenchymal cells will form a dermal papilla, having profound effects on hair follicle formation. The appearance of follicle‐inducing mesenchymal cells in the process of vibrissa follicle development was examined. Mesenchymal cells were isolated from the developing site of vibrissa follicles at 13 days or at later stages and amplified in mass culture, harvested and transplanted in association with the epithelium. It was demonstrated that 13‐day mesenchymal cells did not induce any hair bulbs but those from 14 days or later stages could induce hair‐producing new bulbs or new follicles depending on the association with the follicle epithelium or with the glabrous sole epidermis of the adult rats, respectively. Further, clones having hair bulb‐inducing ability were obtained from 14‐ and 15‐day mass‐cultured mesenchymal cells. Based on these and other results, it was concluded that mesenchymal cells having follicle‐inducing ability are present at least by 14 days in the future whisker pad region. This suggests that the differentiation of the dermal papilla cells must start before the initial hair bud stage.
Stages of normal tracheo‐bronchial development in rat embryos: Resolution of a controversy
Authors: Qi Bao Quan , Beasley Spencer W.
Published: March 2003

The embryonic events surrounding tracheo‐esophageal separation remain controversial. The present study was undertaken to clarify early tracheo‐bronchial development in the rat embryo at a critical period of organogenesis. Twenty‐seven timed‐mated Sprague‐Dawley rats were divided into nine groups of three rats. Their embryos were harvested on gestational days 11–15 at intervals of 8 h, processed and sectioned transversely. The sections were stained with hematoxylin and eosin and examined serially. The foregut is a single tube on gestational day 11. During the following 16 h, there is localized and rapid growth of the respiratory epithelium and a latero‐ caudal expansion to form the bronchial buds and a protuberance on the ventral wall of the foregut (future tracheal carina). From gestational days 12–12 + 8, cellular debris and apoptotic epithelial cells are specifically located in the tracheo‐esophageal groove, resulting in collapse and fusion of the lateral walls of the foregut, effectively separating the trachea and esophagus. Afterwards, the epithelial proliferation dominates the process of tracheo‐esophageal separation until it reaches the caudal end of the laryngeal epithelial lamina on gestational day 15. The present study shows that separation of the trachea from the esophagus involves three consecutive stages: (i) epithelial proliferation resulting in the formation of bronchial buds and the tracheal carina; (ii) epithelial apoptosis leading to separation of the trachea and esophagus; and (iii) epithelial proliferation to complete the separation process.
Synergistic effects of FGF and non‐ridge ectoderm on gene expression involved in the formation of the anteroposterior axis of the chick limb bud in cell culture
Authors: Kimura Jun , Sato‐Maeda Mika , Noji Sumihare , Ide Hiroyuki
Published: March 2003

Skeletal patterning of the vertebrate limb is controlled by the zone of polarizing activity (ZPA), apical ectodermal ridge (AER) and dorsal ectoderm. In the present study, to understand the involvement of fibroblast growth factor (FGF) and non‐ridge ectoderm in anteroposterior (AP) axis formation, gene expression in chick limb bud mesenchymal cells in culture was investigated by reverse transcription–polymerase chain reaction and in situ hybridization. It was found that Shh expression was locally maintained in the mesenchymal cells underneath and near non‐ridge ectoderm in coculture with the posterior mesenchymal cells and non‐ridge ectoderm in the presence of FGF‐4 by in situ hybridization. In Shh‐expressing anterior limb bud mesenchymal cells cultured with non‐ridge ectoderm, it was also discovered that Bmp‐2 was activated in the presence of FGF‐2, ‐4 and ‐8, while Hoxd‐13 was activated in the presence of FGF‐4 and that FGF‐2 had a similar effect but FGF‐8 did not. This result indicates that Hoxd‐13 activation by SHH depends on non‐ridge ectoderm and FGF‐2 or FGF‐4, and that there may be a difference in the effect on AP axis formation of the limb bud between FGF‐2, ‐4 and ‐8. Possible roles of these genes and signal molecules in AP pattern formation are discussed.
Centriole behavior during meiosis in oocytes of the sea urchin Hemicentrotus pulcherrimus
Authors: Nakashima Seiko , Kato Koichi H.
Published: March 2003

Ultrastructural changes in the maturing oocyte of the sea urchin Hemicentrotus pulcherrimus were observed, with special reference to the behavior of centrioles and chromosomes, using oocytes that had spontaneously started the maturation division process in vitro after dissection from ovaries. The proportion of oocytes entering the maturation process differed from batch to batch. In those eggs that accomplished the maturation division, it took ~4.5–5 h from the beginning of germinal vesicle breakdown to the formation of a second polar body. Serial sections revealed that a young oocyte before germinal vesicle breakdown had a pair of centrioles with procentrioles, located between the presumed animal pole and the germinal vesicle and accompanied by amorphous aggregates of moderately dense material and dense granules (granular aggregate). Just before germinal vesicle breakdown, a pair of fully grown centrioles located in the granular aggregate, which is present until this stage and then disappears, had already separated from another pair of centrioles. In meiosis I, each division pole had two centrioles, whereas in meiosis II each had only one. The two centrioles in the secondary oocyte separated into single units and formed the mitotic figure of meiosis II. The first polar body had two centrioles and the second had only one. The two centrioles in the first polar body did not form the mitotic figure nor did they separate at the time of meiosis II. These results indicate that, in sea urchins, duplication of the centrioles does not occur during the two successive meiotic divisions and the egg inherits only one centriole from the primary oocyte, confirming the results previously reported for starfish oocytes.
Maternal Nanos and Pumilio regulate zygotic vasa expression autonomously in the germ‐line progenitors of Drosophila melanogaster embryos
Authors: Sano Hiroko , Mukai Masanori , Kobayashi Satoru
Published: March 2003

vasa (vas) is transcribed earliest among reported genes expressed in the germ‐line progenitors, or pole cells, in Drosophila melanogaster embryos. Its expression is detected in the germ‐line cells throughout their development, making vas expression a useful marker for the establishment of germ‐line fate. In the present report, it is shown that maternal Nos and Pum are required for normal expression of vas in pole cells. First, expression of enhancer‐trap marker BC69, which reflects vas expression, is promoted by maternal Nos and Pum. Second, expression of vas mRNA in pole cells is promoted by maternal Nos and Pum. Third, pole cell transplantation experiments reveal that maternal Nos and Pum are required autonomously in pole cells for proper expression of vas. Finally, Nos and Pum are dispensable for vas expression in oogenesis, although they are expressed zygotically in adult ovaries. These observations show that germ‐line‐specific vas expression is promoted by autonomous function of maternal Nos and Pum in the germ‐line progenitors during embryogenesis, and is regulated differentially in embryogenesis and oogenesis..
Acrosome reaction in spermatozoa from hagfish (Agnatha) Eptatretus burgeri and Eptatretus stouti: Acrosomal exocytosis and identification of filamentous actin
Authors: Morisawa Sachiko , Cherr Gary N.
Published: March 2003

Spermatozoa of the hagfishes Eptatretus burgeri and Eptatretus stouti, caught in the sea near Japan and North America, respectively, were found to undergo the acrosome reaction, which resulted in the formation of an acrosomal process with a filamentous core. The acrosomal region of spermatozoa of E. stouti exhibited immunofluorescent labeling using an actin antibody. The midpiece also labeled with the antibody. The acrosomal region showed a similar labeling pattern when sperm were probed with tetramethylrhodamine isothyocyanate (TRITC)‐phalloidin; the midpiece did not label. Following induction of the acrosome reaction with the calcium (Ca2+) ionophore ionomycin, TRITC‐phalloidin labeling was more intense in the acrosomal region, suggesting that the polymerization of actin occurs during formation of the acrosomal process, as seen in many invertebrates. The potential for sperm to undergo acrosomal exocytosis was already acquired by late spermatids. During acrosomal exocytosis, the outer acrosomal membrane and the overlying plasma membrane disappeared and were replaced by an array of vesicles; these resembled an early stage of the acrosome reaction in spermatozoa of higher vertebrates in which no formation of an acrosomal process occurs. It is phylogenetically interesting that such phenomena occur in spermatozoa of hagfish, a primitive vertebrate positioning between invertebrates and high vertebrates.
Essential role of growth factor receptor‐mediated signal transduction through the mitogen‐activated protein kinase pathway in early embryogenesis of the echinoderm
Authors: Katow Hideki , Aizu Goh
Published: March 2003

In this study it was shown that growth factor receptors (GFR) play a crucial role in early embryogenesis of the echinoderms Hemicentrotus pulcherrimus and Clypeaster japonicus by transmitting signals to the mitogen‐activated protein kinase (MAPK) pathway. The phosphorylation ratio of extracellular signal‐regulated kinase 1 (ERK1) changed dynamically during early embryogenesis and showed a peak at the swimming blastula (sBl) stage. Suramin, an inhibitor of GFR, when applied during the sBl stage perturbed morphogenesis, including primary mesenchyme cell (PMC) migration, cell proliferation, archenteron elongation, spiculogenesis, pigment cell differentiation and phosphorylation of myosin light chains (MLC). Genistein, a receptor‐type protein tyrosine kinase inhibitor, severely inhibited PMC migration, gastrulation and the phosphorylation of MLC. Manumycin A, a Ras inhibitor, inhibited spiculogenesis and invagination. PD98059, a MAPK/ERK kinase inhibitor, perturbed early PMC migration and pigment cell differentiation, but not spiculogenesis and gastrulation (although these two events were significantly delayed). PMC ingression was not perturbed by genistein, suramin, manumycin A or PD98059. All of the inhibitors perturbed the phosphorylation of ERK1, which was completely restored by exogenous platelet‐derived growth factor (PDGF)‐AB. PDGF‐AB also partially restored elongation of the archenteron by restoring cell proliferation that had been perturbed by suramin.
Oxygen isotope ratios between soil water and stem water of trees in pot experiments
Authors: Takahashi Kazushi
Published: March 2003

Since the oxygen isotopic ratio of water extracted from stems reflects that of water taken up by roots, the stem water isotope ratio can be used to analyze the source of water for plant growth. However, it is known that the fractionation of isotopes during evaporation from the surface soil increases the isotope ratio in soil water drastically. In this study, it was experimentally confirmed that the stem water of Elaeocarpus sylvestris vs. ellipticus Hara seedlings is not isotopically similar to the water source in the case where evaporation from the soil occurs actively. However, since water in these plant bodies was replaced in about 2 days in the pot experiments, the 2‐day‐averaged values of the soil water isotope ratio approached the stem water isotope ratio. Thus, time‐course samplings of the soil and stems, and measurements of the replacement time of water in the plant body (water volume in plant/transpiration rate) are recommended for correct interpretation of the isotopic signature of soil water and stem water.
Quantities and types of ectomycorrhizal and endophytic fungi associated with Betula platyphylla var. japonica seedlings during the initial stage of establishment of vegetation after disturbance
Authors: Hashimoto Yasushi , Hyakumachi Mitsuro
Published: March 2003

Ectomycorrhizal and endophytic fungi of Betula platyphylla Sukatchev var. japonica Hara seedlings were investigated by bioassay using soils from sites where the surface layer had been removed by destructive disturbances. Soil samples were taken from sites A, B, C and D, where 1, 2–3, 4–5, and 7–8 years, respectively had passed since disturbance. Naturally regenerated B. platyphylla var. japonica seedlings grew at sites C and D, but not at sites A or B. The percentages of ectomycorrhizal formation in seedlings were significantly lower in the soils from site A (4%) and site B (13%), compared to those in the soils from site C (53%) and site D (37%). The numbers of ectomycorrhizal morphologic types in sites A, B, C, and D were eight, five, one, and seven, respectively. The same dominant type of ectomycorrhiza was found in sites C and D, and this type was different from those in sites A and B. The frequencies of colonization of seedling roots by endophytic fungi, especially Mycelium radicis atrovirens Melin (MRA) in soils from sites A and B were 31 and 33%, respectively; these frequencies were significantly higher than those for site C (0%) and site D (2%). During the initial stage of establishment of vegetation following disturbance, the quantities and types of ectomycorrhizal fungi in the field that have the potential to associate with B. platyphylla var. japonica might rapidly change after invasion of the host plant. Ectomycorrhizal fungi seemed to compete with endophytic MRA fungi for colonization of the roots of B. platyphylla var. japonica seedlings.
An initial comparison of growth rates in the rare grass Achnatherum hendersonii and its common associate Poa secunda
Authors: Binney Elizabeth P. , Bradfield Gary E.
Published: March 2003

The rare grass, Achnatherum hendersonii (Vasey) Barkworth, and the more widely distributed Poa secunda J. S. Presl grow together on shallow soils derived from basaltic rock that are subject to cryogenic disturbance. It has been proposed that the solifluction allows A. hendersonii to persist by inhibiting the competitive ability of P. secunda. A correlate of this proposal is that P. secunda will have a superior growth rate in undisturbed soils. This idea was tested by growing both species in potting soil, both singly and in combination. Under these conditions, P. secunda grew faster and attained a larger above‐ground size than A. hendersonii. Thus, one factor allowing the survival of the rare A. hendersonii seems to be its occurrence on sites where the competitive ability of a wide‐ranging species is restricted. The survival of A. hendersonii on disturbed sites may also be partly explained by its roots that are apparently adapted to growing where solifluction occurs.
Higher mortality of smaller sika deer fawns
Authors: Takatsuki Seiki , Matsuura Yukiko
Published: March 2003

Bodyweight, breast girth and hind‐foot length were compared in sika deer fawns (Cervus nippon Temminck) that were shot or had died naturally. The study site was Mount Goyo, in northern Japan. Samples were collected in January and February every year from 1982 to 1991 for the dead fawns and from 1990 to 1992 for the living fawns. The average bodyweight and the variation in bodyweight was significantly smaller in the dead fawns than in the living ones, suggesting a higher mortality rate in smaller fawns. The mean breast girth and hind‐foot length were also significantly smaller in the dead fawns. Two possibilities are suggested: (i) the smaller fawns were born later than the larger fawns and grew at normal rates; or (ii) the smaller and larger fawns were born in a similar period but grew at different rates thereafter.
Food habits of sika deer and nutritional value of sika deer diets in eastern Hokkaido, Japan
Authors: Yokoyama Mayumi , Kaji Koichi , Suzuki Masatsugu
Published: March 2003

Rumen content analysis and field observations were used to investigate the food habits and diet quality of sika deer (Cervus nippon yesoensis Heude) from 1991 to 1993 in eastern Hokkaido, Japan. Diets varied seasonally, with deer consuming graminoids and browse in winter, forbs and agricultural crops in spring and summer and all of these plant foods in autumn. Eighty‐four plant species with sika deer bite marks were identified and their use also varied seasonally. The diversity of food resources available provided both critical protein and digestible energy, allowing for physiological maintenance and seasonal growth. With these high‐quality diets, deer maintained good body condition in eastern Hokkaido, where the population density was relatively low.
Seed dispersal by Japanese marten Martes melampus in the subalpine shrubland of northern Japan
Authors: Otani Tatsuya
Published: March 2003

The functions of carnivorous mammals as seed dispersers were studied during a snow‐free period of 2 years in the subalpine shrubland of northern Japan. Mammal appearances, which were recorded using three automatic cameras, were dominated by Japanese marten, Martes melampus (Wagner), followed by three carnivores (ermine, red fox, and raccoon dog) and two other mammals (field mouse and Japanese hare). Fecal analysis revealed that the martens dispersed seeds of 11 species (eight woody and three herbaceous plants), which included a vine species that is an inhabitant of lower elevation sites. Fruit weight and size, and flesh weight and volume of the fleshy‐fruited species foraged by the martens were significantly greater than those that were not foraged. These facts indicate that the marten plays a key role as a relatively long‐distance seed disperser for major component species with large and flesh‐rich fruits in the subalpine shrubland.
Distribution of cave‐dwelling bats and conservation status of underground habitats in the Istanbul area
Authors: Furman Andrzej , Özgül Arpat
Published: March 2003

Populations of cave‐dwelling bat species were investigated in the transitory region between the Eastern Thrace and the Western Pontus. Data were collected during 30 surveys in 13 underground sites, 10 of which had not been surveyed previously by bat researchers, between March 1999 and March 2000. Approximately 20 000 bats representing eight species were recorded. Grouping the sites according to their ecological resemblance, by means of cluster and correspondence analyses, yielded different results for the summer and winter data. In summer, there was a partial separation of the sites by their location in biogeographic regions. In winter, no regional grouping was observed. It was concluded that in the transitory region, species distribution does not differ considerably between the Eastern Thracian and Western Pontic ecosystems. In addition, a conservation scoring system is proposed for those sites investigated, their status is evaluated, and the most important local roosts are identified.
Termite ecology in a dry evergreen forest in Thailand in terms of stable (δ13C and δ15N) and radio (14C, 137Cs and 210Pb) isotopes
Authors: Tayasu Ichiro , Nakamura Toshio , Oda Hirotaka , Hyodo Fujio , Takematsu Yoko , Abe Takuya
Published: March 2003

Stable (δ13C and δ15N) and radio‐ (14C,

137Cs and 210Pb) isotopes were determined for termites that

have been sampled from a dry evergreen forest in Thailand. A wood‐feeding termite,

Microcerotermes crassus, was separated from soil‐feeders: Termes propinquus,

Termes comis and Dicuspiditermes makhamensis by δ13C

and δ15N values. The Termes group in Thailand had less diverse

values in δ13C and δ15N than those in Australia, where

the feeding habits of the ‘Termes’ group are more diverse. Other

soil‐feeding termites produced similar δ13C values, but a larger range

in δ15N values. 14C‐percent modern carbon (pMC) values

suggest that the soil‐feeding termites used younger carbon than the wood‐feeding

termites, and this was consistent with the termites from Cameroon, central Africa.

Values of δ13C and 14C‐pMC indicate that surface soil was

used by a soil‐feeding termite, D. makhamensis, in making the nest mounds,

and deeper soil (10–30 cm) by a fungus‐growing termite, Macrotermes carbonarius.

210Pb and 137Cs were scarcely incorporated into the termites,

although 214Pb was recovered from the workers. The results suggest that stable‐ and radioisotopes are useful in the study of detritivorous animals, organic matter decomposition and ecosystem engineering.
Light utilization and competition between Echinacea purpurea, Panicum virgatum and Ratibida pinnata under greenhouse and field conditions
Authors: Knee Michael , Thomas Laura C.
Published: March 2003

Competitive interactions were compared under field and greenhouse conditions for three representative tallgrass prairie species, Echinacea purpurea, Panicum virgatum and Ratibida pinnata. These were planted in monoculture and in mixtures of two species using a replacement series design with groups of four or eight plants. Competition was determined from shoot dry weight data collected during 120 days in the greenhouse and after 415 days in the field. Yields declined with increased density of a single species in the greenhouse from 40 days onward and in the field. Relative yields were up to 100% higher in mixtures than in monocultures for all species early on in the greenhouse experiment. Later in the experiment and in the field relative yields of E. purpurea decreased in the presence of P. virgatum and R. pinnata, whereas relative yields of these two species increased in the presence of E. purpurea. There were correlations in relative yield between the field and the greenhouse experiment at 80 and 120 days. In the greenhouse P. virgatum maintained higher net assimilation rates than the other species. Relative growth rates of all species were higher in monoculture and in mixtures up to 40 days, after which they declined, especially for E. purpurea in mixtures. In the field, higher light intensities occurred in pure stands of E. purpurea than in mixed stands with other species. The order of competitive ability that was apparent from these field and greenhouse studies, P. virgatum = R. pinnata > E. purpurea, could be partially explained by photosynthetic rates in relation to canopy light interception.
Importance of clonal plants and plant species diversity in the Northeast China Transect
Authors: Song Minghua , Dong Ming , Jiang Gaoming
Published: March 2003

In plant communities, the internal (genet‐level) control mechanisms on a spatio‐temporal scale of clonal plants impose strong constraints on spatial pattern as well as on competitive relations and, thus, species coexistence. Therefore, the presence of clonal species within a plant community affects spatio‐temporal dynamics and plant species diversity. We examined the distribution of plants with different clonal growth forms in the Northeast China Transect (NECT) and correlated plant species diversity with the importance of clonal plants, and the importance of phalanx and guerilla clonal plants. Phalanx clonal plants were more abundant in western communities where the altitude was higher and both the soil nitrogen contents and precipitation were relatively low. Whereas guerilla clonal plants were more abundant in the middle of the NECT where the precipitation, mean annual temperature and photosynthetically active radiation were relatively high. In the relatively productive temperate typical steppe, plant species diversity was negatively correlated with the importance of phalanx clonal plants and positively correlated with the importance of guerilla clonal plants. In relatively unproductive temperate desert steppe, plant species diversity was positively correlated with the importance of both phalanx and guerilla clonal plants.
Population dynamics and the color of environmental noise: A study on a three‐species food chain system
Authors: XU CAI‐LIN , LI ZI‐ZHEN
Published: March 2003

In the present study, the effect of ‘red’, ‘white’ and ‘blue’ environmental noise on population dynamics in a simple three‐species food chain system was analyzed. The ‘colored’ noise was superimposed on the three‐species food chain model first put forth by Rosenzweig in different ways and the resulting power spectra were investigated. We showed that the amplitude of environmental noise, the trophic level at which a population is positioned and whether a population is directly affected by environmental noise, are all important with respect to the way in which a population responds to noise with different colors. For the deterministic case, all population dynamics are ‘red’ irrespective of the system dynamics. When all species are sensitive to environmental noise, the top predator's dynamics always remain ‘red’ regardless of the color of the noise and its amplitude, whereas the dynamics of the intermediate species turn ‘blue’ under disturbances of any color with high amplitude, and those of the basal species may become ‘blue’ only under ‘blue’ noise. If only one species is sensitive to environmental noise, the dynamics of the insensitive species are always ‘red’, irrespective of the color of the noise and its amplitude. Unlike previous results obtained by studying single‐species models, our results have almost nothing to do with deterministic system dynamics. In other words, changing the deterministic system dynamics from stable via periodic to chaotic does not qualitatively change the outcome. Our results are of importance in determining how we interpret the ubiquitous ‘red’ power spectrum of natural ecological time series.
Burnout in emergency physicians and trainees in Australasia
Authors: Goh Leong , Cameron Peter A , Mark Paul
Published: March 2003

Objective: To measure the prevalence of burnout and potential cases of psychiatric disorder among emergency physicians and advanced trainees of emergency medicine in Australasia.

Methods: A postal survey of all Fellows and advanced trainees of the Australasian College for Emergency Medicine using the Maslach Burnout Inventory and General Health Questionnaire‐28 was performed.

Results: The survey showed that 71.8% of respondents had moderate to high levels of emotional exhaustion, 69.9% had moderate to high levels of depersonalization and 48.7% had moderate to low perception of personal accomplishment. A General Health Questionnaire‐28 score of 6 or more, indicating potential cases of psychiatric disorder, was seen in 26.8% of respondents. Burnout was correlated with male gender, trainee status, longer working hours, weekend shifts, shift work, work dissatisfaction, self‐report of feeling stressed and a desire to stop working in the emergency department within 10 years.

Conclusions: There are emergency physicians and advanced trainees of emergency medicine working in emergency departments suffering from considerable burnout with a risk of psychiatric disorder. Those with burnout are likely to consider stopping work in the emergency department within 10 years. Interventions to improve the wellbeing of these doctors should be considered.
Renal colic: A diagnostic and therapeutic review
Authors: Holdgate Anna , Hardcastle Jan
Published: March 2003

Renal colic is a common presenting problem in emergency departments where the focus of treatment is on prompt analgesia, limited supportive investigations and exclusion of other serious disorders. This review gives an overview of the pathophysiology of this condition and those aspects of its care that are specific to the emergency department. The role of narcotics and non‐steroidal anti‐inflammatory drugs in treatment is examined, and the available imaging techniques are described and evaluated. Alternative diagnoses and indications for hospital admission are discussed.
Neurogenic pulmonary oedema
Authors: Rehman Habib U
Published: March 2003

Although neurogenic pulmonary oedema is an uncommon condition, it is found in 20% of victims with severe head injury. The onset is typically rapid with development of dyspnoea, cyanosis and hypoxia suddenly and unexpectedly after an intracranial injury. The pathogenesis is not entirely clear, but both increased hydrostatic pressure and capillary permeability are incriminated. It is important to differentiate neurogenic pulmonary oedema from aspiration pneumonia, because the treatment of the two conditions differ. A combination of measures to reduce intracranial pressure, optimize body oxygenation, decrease pre‐ and after‐load and improve cardiac contractility is the mainstay of treatment. Mortality is high despite these measures.
Recent advances in the management of late paracetamol poisoning
Authors: Jones Alison L
Published: March 2003

Management of early paracetamol poisoning is dependent on prompt administration of N‐acetylcysteine to patients whose plasma concentrations of paracetamol exceed the normal‐risk or high‐risk treatment lines. Paracetamol poisoning presenting after 15 h since ingestion, especially as fulminant hepatic failure, requires meticulous supportive care of organ dysfunction. The putative mechanisms of action of N‐acetylcysteine and its practical use are discussed. The best prognostic marker for paracetamol poisoning in ‘established hepatotoxicity’ is the prothrombin time. Indications for liver transplantation in paracetamol poisoning and exclusion criteria are also discussed.