bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative measurement of desquamation and skin elasticity in diabetic patients
Authors: Yoon Hong Seok , Baik Sei Hyun , Oh Chil Hwan
Published: March 2003

Background/aims: Diabetes mellitus is responsible for many cutaneous alterations. Xerosis and sclerotic change of the skin are the most common findings. Recently non‐ invasive computerized devices have been developed and used for determining the desquamation rate and measuring the mechanical properties of the skin. Using these devices, the necessity to characterize the conditions of the skin in the healthy as well as the diseased state is increasing. The aim of this study was to compare the elasticity and desquamation rate between the diabetic population and the normal population using non‐invasive, objective methods.

Methods: Skin sites of 96 diabetics with normal appearance, were measured for skin elasticity and desquamation rate using the Cutometer® and visual grading and D‐Squame®– image analysis method, respectively. The values of parameters were compared to values of 83 non‐diabetics' results.

Results: There was a significant decrease in skin elasticity (expressed by Uv/Ue and Ur/Uf of the face) and in the value of fine flakes in the diabetics. Although insignificant, the SDI (Scale Density Index) calculated from objective automatic measurement was higher in the diabetics than the control group.

Conclusions: The elasticity of facial skin was decreased in patients with diabetes. Decrease of the fine flakes of the diabetes patients reflect that irritation and xerotic changes are aggravated in skins of diabetic patients. The results indicate the presence of skin elasticity alteration and desquamation with diabetes mellitus. Such non‐invasive evaluations of the skin may be useful for evaluating changes in the skin that are associated with diabetes mellitus.
Apical and Basolateral Endocytic Pathways of MDCK Cells Meet in Acidic Common Endosomes Distinct from a Nearly‐Neutral Apical Recycling Endosome
Authors: Wang Exing , Brown Paul S. , Aroeti Benjamin , Chapin Steven J. , Mostov Keith E. , Dunn Kenneth W.
Published: March 2003

Quantitative confocal microscopic analyses of living, polarized MDCK cells demonstrate different pH profiles for apical and basolateral endocytic pathways, despite a rapid and extensive intersection between the two. Three‐dimensional characterizations of ligand trafficking demonstrate that the apical and basolateral endocytic pathways share early, acidic compartments distributed throughout the medial regions of the cell. Polar sorting for both pathways occurs in these common endosomes as IgA is sorted from transferrin to alkaline transcytotic vesicles. While transferrin is directly recycled from the common endosomes, IgA is transported to a downstream apical compartment that is nearly neutral in pH. By several criteria this compartment appears to be equivalent to the previously described apical recycling endosome. The functional significance of the abrupt increase in lumenal pH that accompanies IgA sorting is not clear, as disrupting endosome acidification has no effect on polar sorting. These studies provide the first detailed characterizations of endosome acidification in intact polarized cells and clarify the relationship between the apical and basolateral endocytic itineraries of polarized MDCK cells. The extensive mixing of apical and basolateral pathways underscores the importance of endocytic sorting in maintaining the polarity of the plasma membrane of MDCK cells.
Phospholipase A2 Antagonists Inhibit Constitutive Retrograde Membrane Traffic to the Endoplasmic Reticulum
Authors: de Figueiredo Paul , Drecktrah Dan , Polizotto Renee S. , Cole Nelson B. , Lippincott‐Schwatrz Jennifer , Brown William J.
Published: March 2003

Eukaryotic cells contain a variety of cytoplasmic Ca2+‐dependent and Ca2+‐independent phospholipase A2s (PLA2s; EC 2.3.1.2.3). However, the physiological roles for many of these ubiquitously‐expressed enzymes is unclear or not known. Recently, pharmacological studies have suggested a role for Ca2+‐independent PLA2 (iPLA2) enzymes in governing intracellular membrane trafficking events in general and regulating brefeldin A (BFA)‐stimulated membrane tubulation and Golgi‐to‐endoplasmic reticulum (ER) retrograde membrane trafficking, in particular. Here, we extend these studies to show that membrane‐permeant iPLA2 antagonists potently inhibit the normal, constitutive retrograde membrane trafficking from the trans‐Golgi network (TGN), Golgi complex, and the ERGIC‐53‐positive ER‐Golgi‐intermediate compartment (ERGIC), which occurs in the absence of BFA. Taken together, these results suggest that iPLA2 enzymes play a general role in regulating, or directly mediating, multiple mammalian membrane trafficking events.
Endocytosis in Viral Replication
Authors: Marsh Mark , Pelchen‐Matthews Annegret
Published: March 2003

Although initially recognised as essential for the entry of certain viruses, endocytosis is now known to also play important roles in the replication of, and adaptation to, the host cell of a number of viruses. Here we consider several aspects of this association and recent results that have emerged to support this view.
Biogenesis of Insulin‐Responsive GLUT4 Vesicles is Independent of Brefeldin A‐Sensitive Trafficking
Authors: Martin Sally , Ramm Georg , Lyttle Chris T. , Meerloo Timo , Stoorvogel Willem , James David E.
Published: March 2003

Insulin stimulates translocation of GLUT4 from an intracellular compartment to the plasma membrane in adipocytes. As a significant amount of GLUT4 is localised to the TGN, independently of the biosynthetic pathway, one possibility is that trafficking via the TGN is important in either intracellular sequestration or insulin‐dependent movement to the cell surface. In this study we have used immuno‐electron microscopy to show that GLUT4 is localised to AP‐1 vesicles in the TGN region in 3T3‐L1 adipocytes. To dissect the role of this trafficking pathway we used brefeldin A (BFA) to disrupt AP‐1 association with membranes. Despite a reorganisation of GLUT4 compartments following BFA treatment, the intracellular sequestration of GLUT4, and its insulin‐dependent movement to the cell surface, was unaffected. BFA increased the half time of reversal of insulin‐stimulated glucose transport from 17 to 30 min but did not prevent complete reversal. Furthermore, following reversal re‐stimulation of glucose transport activity by insulin was not compromised. We conclude that under basal conditions GLUT4 cycles between the TGN and endosomes via the AP‐1 pathway. However, neither this pathway, nor any other BFA‐sensitive pathway, appears to play a major role in insulin‐dependent recruitment of GLUT4 to the cell surface.
Analysis of the Lysosomal Storage Disease Chediak–Higashi Syndrome
Authors: McVey Ward Diane , Griffiths Gillian M. , Stinchcombe Jane C. , Kaplan Jerry
Published: March 2003

Chediak–Higashi syndrome (CHS) is a rare autosomal recessive disorder of human, mouse (beige) and other mammalian species. The same genetic defect was found to result in the disease in all species identified, permitting a positional cloning approach using the mouse model beige to identify the responsible gene. The CHS gene was cloned and mutations identified in affected species. This review discusses the clinical features of CHS contrasting features seen in similar syndromes. The possible functions of the protein encoded by the CHS/beige gene are discussed, along with the alterations in cellular physiology seen in mutant cells.
Traffic Jam: A Compendium of Human Diseases that Affect Intracellular Transport Processes
Authors: Aridor Meir , Hannan Lisa A.
Published: March 2003

As sequencing of the human genome nears completion, the genes that cause many human diseases are being identified and functionally described. This has revealed that many human diseases are due to defects of intracellular trafficking. This ‘Toolbox’ catalogs and briefly describes these diseases.
Two Independent Regions of HIV‐1 Nef are Required for Connection with the Endocytic Pathway Through Binding to the μ1 Chain of AP1 Complex
Authors: Erdtmann1, Lars , Janvier Katy , Raposo Graça , Craig Heather M. , Benaroch Philippe , Berlioz‐Torrent Clarisse , Guatelli John C. , Benarous Richard , Benichou Serge
Published: March 2003

The Nef protein from the human immunodeficiency virus (HIV) induces down‐regulation of the CD4 and major histocompatibility complex class I molecules from the cell surface by interfering with the endocytic machinery. This work focuses on the interaction of HIV‐1 Nef with the μ1 chain of adaptor protein type 1 (AP1) complex and its contribution to the Nef‐induced alterations of membrane trafficking. Two independent regions surrounding a disordered loop located in the C‐terminal part of Nef are involved in μ1 binding. Each region can separately interact with μ1, and simultaneous point mutations within both regions are needed to abolish binding. We used CD8 chimeras in which the cytoplasmic tail was replaced by Nef mutants to show that these μ1‐binding sites contain determinants required to induce CD4 down‐regulation and to target the chimera to the endocytic pathway by promoting AP1 complex recruitment. Ultrastructural analysis revealed that the CD8‐Nef chimera provokes morphological alterations of the endosomal compartments and co‐localizes with AP1 complexes. These data indicate that the recruitment by Nef of AP1 via binding to μ1 participates in the connection of Nef with the endocytic pathway.
The Actin Cytoskeleton is Required for the Trafficking of the B Cell Antigen Receptor to the Late Endosomes
Authors: Brown Bruce K. , Song Wenxia
Published: March 2003

The B cell antigen receptor (BCR) plays two central roles in B cell activation: to internalize antigens for processing and presentation, and to initiate signal transduction cascades that both promote B cells to enter the cell cycle and facilitate antigen processing by accelerating antigen transport. An early event in B cell activation is the association of BCR with the actin cytoskeleton, and an increase in cellular F‐actin. Current evidence indicates that the organization of actin filaments changes in response to BCR‐signaling, making actin filaments good candidates for regulation of BCR‐antigen targeting. Here, we have analyzed the role of actin filaments in BCR‐mediated antigen transport, using actin filament‐disrupting reagents, cytochalasin D and latrunculin B, and an actin filament‐stabilizing reagent, jasplakinolide. Perturbing actin filaments, either by disrupting or stabilizing them, blocked the movement of BCR from the plasma membrane to late endosomes/lysosomes. Cytochalasin D‐treatment dramatically reduced the rate of internalization of BCR, and blocked the movement of the BCR from early endosomes to late endosomes/lysosomes, without affecting BCR‐signaling. Thus, BCR‐trafficking requires functional actin filaments for both internalization and movement to late endosomes/lysosomes, defining critical control points in BCR‐antigen targeting.
Organization of the Rab‐GDI/CHM Superfamily: The Functional Basis for Choroideremia Disease
Authors: Alory Christelle , Balch William E.
Published: March 2003

Choroideremia is an X‐chromosome‐linked disease that leads to the degeneration of the choriocapillaris, the retinal pigment epithelium and the photoreceptor layer in the eye. The gene product defective in choroideremia, CHM, is identical to Rab escort protein 1 (REP1). CHM/REP1 is an essential component of the catalytic geranylgeranyltransferase II complex (GGTrII) that delivers newly synthesized small GTPases belonging to the RAB gene family to the catalytic complex for post‐translational modification. CHM/REP family members are evolutionarily related to members of the guanine nucleotide dissociation inhibitor (GDI) family, proteins involved in the recycling of Rab proteins required for vesicular membrane trafficking through the exocytic and endocytic pathways, forming the GDI/CHM superfamily. Biochemical and structural analyses have now revealed a striking parallel in the organization and function of these two families allowing us to generate a general model for GDI/CHM superfamily function in health and disease.
The Nuclear Envelope in Muscular Dystrophy and Cardiovascular Diseases
Authors: Burke Brian , Mounkes Leslie C. , Stewart Colin L.
Published: March 2003

Considerable interest has been focused on the nuclear envelope in recent years following the realization that several human diseases are linked to defects in genes encoding nuclear envelope specific proteins, most notably A‐type lamins and emerin. These disorders, described as laminopathies or nuclear envelopathies, include both X‐linked and autosomal dominant forms of Emery–Dreifuss muscular dystrophy, dilated cardiomyopathy with conduction system defects, limb girdle muscular dystrophy 1B with atrioventricular conduction disturbances, and Dunnigan‐type familial partial lipodystrophy. Certain of these diseases are associated with nuclear structural abnormalities that can be seen in a variety of cells and tissues. These observations clearly demonstrate that A‐type lamins in particular play a central role, not only in the maintenance of nuclear envelope integrity but also in the large‐scale organization of nuclear architecture. What is not obvious, however, is why defects in nuclear envelope proteins that are found in most adult cell types should give rise to pathologies associated predominantly with skeletal and cardiac muscle and adipocytes. The recognition of these various disorders now raises the novel possibility that the nuclear envelope may have functions that go beyond housekeeping and which impact upon cell‐type specific nuclear processes.
The ER to Golgi Interface is the Major Concentration Site of Secretory Proteins in the Exocrine Pancreatic Cell
Authors: Oprins Ad , Rabouille Catherine , Posthuma George , Klumperman Judith , Geuze Hans J. , Slot Jan W.
Published: March 2003

By using quantitative immuno‐electron microscopy of two‐sided labeled resin sections of rat exocrine pancreatic cells, we have established the relative concentrations of the secretory proteins amylase and chymotrypsinogen in the compartments of the secretory pathway. Their total concentration over the entire pathway was ∼ 11 and ∼ 460 times, respectively. Both proteins exhibited their largest increase in concentration between the endoplasmic reticulum and cis‐Golgi, where they were concentrated 3–4 and 50–70 times, respectively. Over the further pathway, increases in concentration were moderate, albeit two times higher for chymotrypsinogen than for amylase. From trans‐Golgi to secretory granules, where the main secretory protein concentration is often thought to occur, relatively small concentration increases were observed. Additional observations on a third secretory protein, procarboxypeptidase A, showed a concentration profile very similar to chymotrypsinogen. The relatively high concentration of amylase in the early compartments of the secretory route is consistent with its exceptionally slow intracellular transport. Our data demonstrate that secretory proteins undergo their main concentration between the endoplasmic reticulum and cis‐Golgi, where we have previously found concentration activity associated with vesicular tubular clusters (Martínez‐Menárguez JA, Geuze HJ, Slot JW, Klumperman J. Cell 1999; 98: 81–90).
GBF1, a Guanine Nucleotide Exchange Factor for ADP‐Ribosylation Factors, is Localized to the cis‐Golgi and Involved in Membrane Association of the COPI Coat
Authors: Kawamoto Kazumasa , Yoshida Yusaku , Tamaki Hideaki , Torii Seiji , Shinotsuka Chisa , Yamashina Shohei , Nakayama Kazuhisa
Published: March 2003

Formation of coated carrier vesicles, such as COPI‐coated vesicles from the cis‐Golgi, is triggered by membrane binding of the GTP‐bound form of ADP‐ribosylation factors. This process is blocked by brefeldin A, which is an inhibitor of guanine nucleotide exchange factors for ADP‐ribosylation factor. GBF1 is one of the guanine nucleotide‐exchange factors for ADP‐ribosylation factor and is localized in the Golgi region. In the present study, we have determined the detailed subcellular localization of GBF1. Immunofluorescence microscopy of cells treated with nocodazole or incubated at 15 °C has suggested that GBF1 behaves similarly to proteins recycling between the cis‐Golgi and the endoplasmic reticulum. Immunoelectron microscopy has revealed that GBF1 localizes primarily to vesicular and tubular structures apposed to the cis‐face of Golgi stacks and minor fractions to the Golgi stacks. GBF1 overexpressed in cells causes recruitment of class I and class II ADP‐ribosylation factors onto Golgi membranes. Furthermore, overexpressed GBF1 antagonizes various effects of brefeldin A, such as inhibition of membrane recruitment of ADP‐ribosylation factors and the COPI coat, and redistribution of Golgi‐resident and itinerant proteins. These observations indicate that GBF1 is involved in the formation of COPI‐coated vesicles from the cis‐Golgi or the pre‐Golgi intermediate compartment through activating ADP‐ribosylation factors.
Clathrin–Protein Interactions
Authors: Lafer Eileen M.
Published: March 2003

There is a complex network of protein–protein and protein–lipid interactions that underlie clathrin‐mediated vesicular traffic in all compartmentalized cells from yeast to man. Major progress has been made in the determination of the three‐dimensional structures of many of the components. Recently, there has been an explosion in the identification and characterization of clathrin binding partners. This review integrates the structural and biochemical information that is currently available to present a unified view of how many clathrin binding partners interact with clathrin.
Accumulation of a GPI‐Anchored Protein at the Cell Surface Requires Sorting at Multiple Intracellular Levels
Authors: Grünfelder Christoph G. , Engstler Markus , Weise Frank , Schwarz Heinz , Stierhof York‐Dieter , Boshart Michael , Overath Peter
Published: March 2003

Proteins modified by glycosylphosphatidylinositol membrane anchors have become popular for investigating the role of membrane lipid microdomains in cellular sorting processes. To this end, trypanosomatids offer the advantage that they express these molecules in high abundance. The parasitic protozoan Trypanosoma brucei is covered by a dense and nearly homogeneous coat composed of a glycosylphosphatidylinositol‐anchored protein, the variant surface glycoprotein, which is essential for survival of the parasite in the mammalian blood. Therefore, T. brucei must possess mechanisms to selectively and efficiently deliver variant surface glycoprotein to the cell surface. In this study, we have quantified the steady‐state distribution of variant surface glycoprotein by differential biotinylation, by fluorescence microscopy and by immunoelectron microscopy on high‐pressure frozen and freeze‐substituted samples. These three techniques provide very similar estimates of the fraction of variant surface glycoprotein located on the cell surface, on average 89.4%. The intracellular variant surface glycoprotein (10.6%) is predominantly located in the endosomal compartment (75%), while 25% are associated with the endoplasmic reticulum, Golgi apparatus and lysosomes. The density of variant surface glycoprotein in the plasma membrane including the membrane of the flagellar pocket, the only site for endo‐ and exocytosis in this organism, is 48–52 times higher than the density in endoplasmic reticulum membranes. The relative densities of the Golgi complex and of the endosomes are 2.7 and 10.8, respectively, compared to the endoplasmic reticulum. This data set provides the basis for an analysis of the dynamics of sorting. Depending on the intracellular itinerary of newly formed variant surface glycoprotein, the high surface density is achieved in two (endoplasmic reticulum → Golgi complex → cell surface) or three enrichment steps (endoplasmic reticulum → Golgi complex → endosomes → cell surface), suggesting sorting between several membrane compartments.
Protein Secretion in Plants: from the trans‐Golgi Network to the Outer Space
Authors: Jürgens Gerd , Geldner Niko
Published: March 2003

Functional analysis of exocytosis in yeast and animal cells has led to the identification of conserved elements and mechanisms of the trafficking machinery over the last decade. Although functional studies of protein secretion in plants are still fairly limited, the Arabidopsis genome sequence provides an opportunity to identify key players of vesicle trafficking that are conserved across the eukaryotic kingdoms. Here, we review and add to recent genome analyses of trafficking components and highlight some plant‐specific modifications of the common eukaryotic machinery. Furthermore, we discuss the evidence for targeted, polarised secretion in plant cells, and speculate about possible underlying cargo sorting processes at the trans‐Golgi network and endosomes, based on what is known in animals and yeast.
Immunohistochemical analysis of CD1a‐labeled Langerhans cells in human dental periapical inflammatory lesions – correlation with inflammatory cells and epithelial cells
Authors: Suzuki T , Kumamoto H , Ooya K , Motegi K
Published: March 2003

OBJECTIVE: Distribution and density of CD1a‐labeled Langerhans cells (LCs) were examined in human dental periapical inflammatory lesions, and compared with inflammatory cell infiltration or epithelial cell proliferation.

MATERIALS AND METHODS: Eighty three periapical lesions (26 apical granulomas (AGs), 8 epitheliated granulomas (EGs), 34 radicular cysts (RCs), 15 residual radicular cysts (RRCs)) were collected. As control, specimens of periodontal ligaments including Malassez epithelial rests were curetted from 21 teeth. LC densities were measured and various degrees of inflammatory cell infiltration were examined immunohistochemically. Labeling indices for the cellular proliferation markers Ki‐67 antigen and DNA topoisomerase II α were calculated in the epithelial components.

RESULTS: LCs were found in all periapical lesions but not in Malassez epithelial rests. LCs were more abundant in epithelial components than in subepithelial layers. Intraepithelial LCs were more frequent in RCs than in RRCs, whereas subepithelial LCs were less frequent in RRCs than in AGs and EGs. T lymphocytes consistently outnumbered macrophages, plasma cells and B lymphocytes. The range of the CD4/CD8‐positive cell ratio differed according to the lesions. Increased LC density was associated with the severity of CD3‐positive cell infiltration. Ki‐67‐ and Topo II – LI showed various degrees of epithelial immunoreactivity. There was a significant correlation between LC density and proliferative potential of the epithelium in periapical lesions.

CONCLUSION: These findings suggested that LCs appeared to be associated with T lymphocyte infiltration and proliferative potential of the epithelial tissue in periapical lesions.
The epidemiology and pathophysiology of HIV – as seen by a South African
Authors: Bekker L‐G
Published: March 2003

The HIV/AIDS epidemic is probably the greatest calamity to befall South Africa. Millions of South Africans and possibly a whole generation will be lost as a result. The health, socioeconomic and personal loss is difficult to quantify. In an attempt to bring this world‐wide problem to a level that can be understood and assimilated, an imaginary town, Kalamatiefontein, has been created. The effects of HIV/AIDS as modelled for South Africa are extrapolated to this town. To illustrate the devastation that a diagnosis of HIV positivity brings to an individual, a young woman from this town is introduced and her story related. Her options in South Africa today are discussed and a general plea is made across the nation for solidarity on this issue.
Oral lesions of HIV infection in developing countries
Authors: Holmes HK , Stephen LXG
Published: March 2003

HIV infection has spread rapidly within developing countries since it was first recognized in the early 1980s. The purpose of this paper is to review the prevalence of oral lesions associated with HIV infection (oral HIV) in the developing world, and to identify additional factors that may complicate the presentation of these lesions. Direct comparison of regional and local prevalence studies within Africa, India and Thailand is speculative because there are few reports available. Furthermore, inherent differences in study design, data collection, standardization and calibration of health workers make any inferences inconclusive. Additional prevalence studies of oral HIV lesions associated with systemic disease or social conditions, such as poverty or malnutrition, are needed. In order to provide a basis for the diagnosis and treatment of HIV‐associated oral lesions in the developing world, it is important to recognize any confounding factors that may impact on their presentation and management. Elucidation of these various factors may provide a basis for treatment within the developing and developed world.
Lichen sclerosus et atrophicus manifesting with localized loss of periodontal attachment
Authors: Jiménez Y , Bagán JV , Milián MA , Gavaldá C , Scully C
Published: March 2003

Lichen sclerosus et atrophicus (LSA) is a chronic mucocutaneous inflammatory disorder of uncertain aetiology that is clinically characterized by the appearance of well delimited white plaques or papules, preferentially affecting the skin and genitals, and more rarely the oral cavity. We present the case of a woman with LSA limited to the oral cavity in the form of a well delimited, flat whitish lesion affecting the vestibular gingiva of the right upper incisors and left central incisor, and extending towards the vestibular fundus and frenulum of the upper lip. Widening of the periodontal space was observed, with gingival recession and attachment loss limited to these teeth. Local corticosteroid injections caused the mucosal lesion but not the periodontal alterations to resolve. Emphasis is placed on the importance of knowledge of this condition in relation to establishing a diagnosis, and on its periodontal repercussions.
Towards international curriculum standards
Authors: Blitz Phebe , Hovius Marjolijn
Published: March 2003

Abstract:  In 1998, the House of Delegates of the International Federation of Dental Hygiene requested that the education committee of the federation develop curriculum guidelines to serve as models for countries that were initiating dental hygiene educational programmes. This article reviews the process of guideline development, identifies challenges and directions for the future. A review of topics, goal and descriptions of 2, 3 and 4 years is presented. The process of development of the guidelines provided an opportunity for discussion of differences in dental hygiene paradigm from various countries. Participants began to understand the legal, cultural and educational differences that have an impact on curriculum for health care. It is a beginning in the process of developing international educational standards in dental hygiene education.
The Ark1/Prk1 family of protein kinases
Authors: Smythe Elizabeth , Ayscough Kathryn R
Published: March 2003

The Ark/Prk serine/threonine kinases initiate phosphorylation cycles that control the endocytic machinery in mammalian cells and in yeast, and the actin cytoskeleton in yeast. The members of this protein family are unified by homologies in their kinase domain, but are generally diverse in their other domains. The evolution of Ark/Prk family members in different organisms may have allowed the conserved role of the kinase domain, which is required for the phosphorylation of both endocytic and cytoskeletal components, to be coupled to other functional domains.
Role of conserved Asp293 of cytochrome P450 2C9 in substrate recognition and catalytic activity
Authors: FLANAGAN Jack U. , McLAUGHLIN Lesley A. , PAINE Mark J.I. , SUTCLIFFE Michael J. , ROBERTS Gordon C.K. , WOLF C. Roland
Published: March 2003

Human cytochrome P450 2C9 (CYP2C9) is important in the metabolism of non-steroidal anti-inflammatory compounds such as diclofenac, the antidiabetic agent tolbutamide and other clinically important drugs, many of which are weakly acidic. Multiple sequence alignment of CYPs identified CYP2C9 Asp293 as corresponding to Asp301 of CYP2D6, which has been suggested to play a role in the binding of basic substrates to the latter enzyme. Replacement of Asp293 with Ala (D293A) decreased activity by more than 90%, and led to an approx. 3- to 10-fold increase in Km values for the three test substrates tolbutamide, dextromethorphan and diclofenac. Conservative replacement of the carboxyl side chain in a Glu (D293E) mutant produced no significant changes in Km values and slight increases in kcat values. Changes in regiospecificity were observed for both the Ala and Glu substitutions; low levels of both dextromethorphan O- and N-demethylation were observed in the D293A mutant, whereas increased preference for O-demethylation was observed for the D293E mutant. Expression of constructs coding for Asn (D293N) and Gln (D293Q) substitutions failed to form a P450 correctly. Our analysis suggests a structural role for the carboxyl side chain of Asp293 in CYP2C9 substrate binding and catalysis. The conservation of an Asp residue in other CYP families in a position equivalent to Asp293 indicates a common mechanism for maintaining the active-site architecture.
Lesions of the Posterior Paraventricular Thalamus Block Habituation of Hypothalamic‐Pituitary‐Adrenal Responses to Repeated Restraint
Authors: Bhatnagar S. , Huber R. , Nowak N. , Trotter P.
Published: March 2003

We examined the role of the posterior division of the paraventricular nucleus of the thalamus (pPVTh) in habituation of hypothalamic‐pituitary‐adrenal (HPA) responses to repeated restraint. Habituation refers to the decrement in HPA activity that occurs with repeated exposure to the same or homotypic stressor. To date, the pPVTh has been shown to inhibit the enhanced or facilitated HPA responses to novel, heterotypic restraint in previously chronically cold stressed rats. We hypothesized that the pPVTh also inhibits HPA activity under conditions of habituation. In the first experiment, we lesioned the pPVTh and examined adrenocorticotropic hormone (ACTH) and corticosterone responses to the first or eighth restraint exposure. In sham‐lesioned rats, we found lower ACTH and corticosterone responses to the eighth period of 30 min restraint compared to the first exposure, evidence for habituation. In pPVTh‐lesioned rats, there was no difference in ACTH and corticosterone responses to the eighth compared to the first restraint exposure. Therefore, pPVTh lesions prevented the habituation of HPA responses to repeated restraint. In the second experiment, we examined whether habituation to restraint is observable in response to an acute, single restraint on day 28 in sham and pPVTh lesioned rats that were exposed to restraint only on days 1 through 8. In this experiment, we replicated the results from the first experiment, and found evidence that habituation to restraint can be observed weeks after chronic stress has been terminated. Furthermore, pPVTh lesions had no additional effects on HPA responses to acute stress on day 28. In summary, pPVTh lesions inhibit habituation of HPA activity to a homotypic stressor, without altering HPA responses to the first restraint. Thus, the intact pPVTh inhibits HPA activity under conditions of habituation, as well as facilitation, and represents an important regulator of HPA activity under conditions of chronic stress.
A microelectrochemical technique to measure trans‐plasma membrane electron transport in plant tissue and cells in vivo
Authors: Taylor A. R. , Chow R. H.
Published: March 2003

A novel electrochemical technique was developed to enable high‐resolution measurements of trans‐plasma membrane reductase activity in vivo in growing plant tissue and single cells. Carbon fibre microelectrodes (CFMEs) with a tip diameter of 5 µm were used for electrochemical mapping of the reduction of the external impermeant electron acceptor ferricyanide along the root tip surface of 4‐d‐old maize seedlings. Ferricyanide reduction was detected in all locations along the first 12 mm of the growing root apex. However, a distinct peak in activity was detected at the proximal end of the elongation zone (1·5–4·5 mm from the apex), where reductase activity was three times greater than in more apical or distal regions. The inhibition of the ferricyanide reduction at all locations along the growing apex, by the vitamin K antagonists warfarin and dicumarol, supports previous data showing that electron transfer by the constitutive trans‐plasma membrane reductase is achieved via a quinone shuttle. We demonstrate that in addition to their utility in whole‐tissue/‐organ studies, CFMEs are sensitive enough to monitor trans‐plasma membrane electron transport in single cells.
Analysis of the O2 dependency in leaf‐level photosynthesis of two Reynoutria japonica populations growing at different altitudes
Authors: Sakata T. , Yokoi Y.
Published: March 2003

To examine the effects of decreased CO2 and O2 partial pressure on leaf‐level photosynthesis in alpine plants at high altitude, we compared the maximal carboxylation efficiency, CE, of Reynoutria japonica Houtt. var. japonica growing in a highland with one growing in a lowland. CE under the native atmospheric conditions (native CE) of the highland population was significantly lower than that of the lowland one. The O2 dependency of CE was significantly less in the highland population than in the lowland. Using theoretical analysis, we explained that O2 dependency of leaf‐level photosynthesis became less as internal conductance (gi) decreased. We also showed that gi and the content of active Rubisco (E) could be estimated from the O2 dependency of leaf‐level photosynthesis. By applying the analysis, a severe limitation of CO2 diffusion in the leaf was estimated in the highland population, whereas almost the same values of E were estimated in both populations. A reasonable explanation for the difference in the native CE is the smaller O2 dependency and photosynthetic capacity caused by a smaller gi in the highland population in addition to the differences in the partial pressures of CO2 and O2.
Differential regional brain growth and rotation of the prenatal human tentorium cerebelli
Authors: Jeffery Nathan
Published: March 2003

Folds of dura mater, the falx cerebri and tentorium cerebelli, traverse the vertebrate endocranial cavity and compartmentalize the brain. Previous studies suggest that the tentorial fold has adopted an increasingly important role in supporting the increased load of the cerebrum during human evolution, brought about by encephalization and an adaptation to bipedal posture. Ontogenetic studies of the fetal tentorium suggest that its midline profile rotates inferoposteriorly towards the foramen magnum in response to disproportionate growth of the cerebrum. This study tests the hypothesis that differential growth of the cerebral and cerebellar components of the brain underlies the inferoposterior rotation of the tentorium cerebelli during human fetal development. Brain volumes and tentorial angles were taken from high‐resolution magnetic resonance images of 46 human fetuses ranging from 10 to 29 gestational weeks. Apart from the expected increases of both supratentorial and infratentorial brain volumes with age, the results confirm previous studies showing a significant relative enlargement of the supratentorial volume. Correlated with this enlargement was a rotation of the midline section of the tentorium towards the posterior cranial base. These findings support the concept that increases of supratentorial volume relative to infratentorial volume affect an inferoposterior rotation of the human fetal tentorium cerebelli. These results are discussed in the context of the role played by the tentorium cerebelli during human evolution and underline implications for phylogenetic and ontogenetic models of encephalization.
Age‐specific breeding probability in black brant: effects of population density
Authors: Sedinger James S. , Lindberg Mark S. , Chelgren Nathan D.
Published: March 2003

We estimated age‐specific probability of breeding for black brant (Branta bernicla nigricansLawrence) (hereafter brant) at the Tutakoke River Colony, Alaska, during a series of years in which local breeding density and juvenile mortality both increased. We use these analyses to examine demographic responses to increased population density.

Estimates of breeding probability were based on Kendall & Nichols (1995) full‐likelihood modification of Pollock’s (1982) robust design applied to observations of uniquely colour‐banded brant.

Breeding probability varied with female age but not across years, indicating lack of response to increased population density. Annual probability of breeding increased from 0·67 ± 0·042 for 2‐year‐old females to 0·90 ± 0·024 for females 5 years old or older.

Annual breeding probability of males ≥ 5 years old was 0·78 ± 0·03. Lower breeding probability of males compared to females probably reflects dispersal of males whose mates died.

Lower juvenile survival appears to be a general response to increased density in large herbivorous birds and mammals, while changes in adult survival and reproductive investment may be more variable.
Non‐parametric modelling of non‐linear density dependence: a three‐species host–parasitoid system
Authors: Kristoffersen A. B. , Lingjærde O. C. , Stenseth N. CHR. , Shimada M.
Published: March 2003

Time‐series data from a twice‐replicated population experiment (consisting of a seed beetle (host), Callosobruchus chinensis, and two parasitoids, Anisopteromalus calandrae and Heterospilus prosopidis) were studied in order to identify and to estimate the density‐dependent structure.

 A non‐parametric host–parasitoid model based on the Nicholson–Bailey model, was studied through non‐parametric autoregressive modelling. An additive non‐linear structure was found in the population growth/parasitism rates for all three species.

 The analysis suggests that the abundance of A. calandrae only weakly affects its own parasitism rate as well as H. prosopidis parasitism rate.

 The analysis also suggests that the net population growth rate of C. chinensis is highly non‐linear, which may be due to disproportionately higher egg mortality at high adult densities.

 Non‐linearity was also demonstrated in the parasitism rate of H. prosopidis, which is consistent with assuming that the density‐dependent mutual interference becomes disproportionately higher at high H. prosopidis adult densities.
Effects of season and fire on the diversity of hypogeous fungi consumed by a tropical mycophagous marsupial
Authors: Vernes Karl , Castellano Michael , Johnson Christopher N.
Published: March 2003

Despite the importance of fire in many natural systems, knowledge of how fire affects the relationship between hypogeous fungi and mycophagous mammals in fire‐prone environments is limited. Using experimental fires, we examined consumption of hypogeous ectomycorrhizal fruit‐bodies by an endangered tropical mycophagist, the northern bettong Bettongia tropica Wakefield, in north‐eastern Australia.

Fungus was the major dietary component (56%) throughout all seasons, both before and after fire. At least 35 hypogeous taxa were consumed. Number of taxa consumed during different seasons was similar, but was significantly higher on unburnt sites than on burnt sites. Similarly, diversity of taxa per faecal sample was significantly greater on unburnt sites, but also increased irrespective of fire from wet season to dry season.

Cluster and principal component analyses were used to examine patterns in consumption of fungal taxa. The greatest differences in dietary composition were between the period immediately after fire on burnt sites (early wet season) and all other season and treatment combinations. This difference was due to increased consumption of taxa in the fire‐adapted family Mesophelliaceae and reduced consumption of the genus Elaphomyces. Principal component analysis revealed two major gradients in consumption. The first accounted for 32% of total variance and described change in consumption of taxa with season. The second accounted for 24% of total variance and described change in consumption of taxa before and after fire.

Despite taxon‐specific changes in consumption of hypogeous fungi, the body condition of bettongs did not change significantly between seasons or in relation to fire, suggesting that bettongs were never compromised in their optimal fungal intake.

Our data show that the northern bettong has a flexible response to fire and could be best thought of as a fire‐adapted marsupial. We therefore propose a precautionary approach to fire management of bettong habitat; at the present time this would include maintaining the recent fire regime of low to moderately intense fires every 3–4 years.
Growth strategies of a shade‐tolerant tropical tree: the interactive effects of canopy gaps and simulated herbivory
Authors: Blundell Arthur G. , Peart David R.
Published: March 2003

We hypothesized that the survival of shade‐tolerant juvenile trees in the understorey depends on allocation strategies that slow their growth but enhance recovery from herbivore damage. In contrast, allocation patterns should maximize height growth in gaps where competitors grow rapidly. We tested the interactive effects of canopy gaps and simulated herbivory (by removing the apical meristem, or 10%, 50% or 90% of tissue from all leaves) on juvenile (< 1 cm diameter at breast height) Shorea quadrinervis Sloot (Dipterocarpaceae), a dominant canopy tree in Borneo.

Damage did not diminish survival over 8 months, except for 90% foliage removal from understorey plants.

Height growth in the understorey was negligible in both control and damaged plants. In gaps, height growth was stimulated by removal of either the apical meristem or 10% of leaf tissue; growth was reduced only after 90% foliage removal.

Higher damage levels increased subsequent net leaf loss. Leaf production was much greater, but leaf retention much lower, in gaps than in the understorey. Ninety per cent foliage removal drastically reduced production in gaps and retention in the understorey. After 10% defoliation, height growth was enhanced in gaps despite approximately 30% net leaf loss.

In a separate experiment, juveniles were moved from a shade house to gaps. After 8 months, gap plants had more leaves and more total biomass, but only half the root : shoot ratio of plants left in the shade.

Allocation patterns, together with the survival of understorey plants after all but the highest levels of damage, indicate that root : shoot allocation there tends to reduce the risk of mortality following herbivore or mechanical damage at the expense of growth. In contrast, in gaps, where interference competition for light is high, resource allocation apparently maximizes height growth.

The interaction between resource availability and herbivore damage provides the basis for a more synthetic theory of resource allocation and growth strategies than one based on resource availability alone.
Patterns of vegetation change and the recovery potential of degraded areas in a coastal marsh system of the Hudson Bay lowlands
Authors: Handa I. T. , Harmsen R. , Jefferies R. L.
Published: March 2003

In recent decades, foraging by increasing numbers of lesser snow geese has led to loss of vegetation and changes in soil conditions in marshes on the Hudson Bay coast.

Changes in species composition were recorded in areas unprotected from goose foraging and in exclosures of varying age (5–15 years) erected in intact swards and on bare sediments where foraging had occurred at La Pérouse Bay, Manitoba.

In the supratidal marsh, plants failed to establish naturally in either open or exclosed (15 years) plots in bare areas. In moist intertidal soils, vegetative fragments of the asexual speciesPuccinellia phryganodesreadily established and formed a mat in exclosures (5 years).

Changes in species assemblages occurred over 11 years in exclosed and adjacent open plots in intertidal and supratidal marshes. Loss of vegetation cover and species richness, particularly dicotyledonous species, and the reversion of later successional plant assemblages to earlier successional assemblages occurred in open plots. In the absence of foraging, late successional graminoids and willow species replaced early successional graminoids.

Late successional grasses of the upper intertidal marsh died when transplanted into degraded soils but still survived after one season in control plots, suggesting that an early successional template is needed for establishment.

In the absence of goose foraging, natural re‐vegetation by clonal propagation can occur only where edaphic conditions are suitable. Within exclosures, vegetation changes resemble those in undamaged areas where goose foraging pressure is still moderate. We propose a state and transition model for vegetation change in the system based on succession patterns, alternative vegetation states and geomorphological events.
Differential expression of inflammation‐ and apoptosis‐related genes in spinal cords of a mutant SOD1 transgenic mouse  model of familial amyotrophic lateral sclerosis
Authors: Yoshihara Tsuyoshi , Ishigaki Shinsuke , Yamamoto Masahiko , Liang Yideng ,   Jun, Niwa Ichi , Takeuchi Hideyuki , Doyu Manabu , Sobue Gen
Published: March 2003

Familial amyotrophic lateral sclerosis (FALS)‐linked mutations in copper–zinc superoxide dismutase (SOD1) cause motor neuron death through one or more acquired toxic properties. We analyzed the molecular mechanism underlying motor neuron degeneration in the transgenic mouse model expressing the SOD1 gene with G93A mutation. Using cDNA microarray, the differentially expressed genes were identified in the spinal cords of G93A mice, 30 being elevated and seven decreased. cDNA microarray analysis to monitor gene expression during neurodegeneration revealed an up‐regulation of genes related to an inflammatory process, such as the tumor necrosis factor‐α (TNF‐α) gene, resulting from glial cell activation, together with the change in apoptosis‐related gene expression, such as caspase‐1. The increased expression of the inflammation‐ and apoptosis‐related genes occurred at 11 weeks of age in the presymptomatic stage prior to motor neuron death. These results suggest a mechanism of neurodegeneration that includes an inflammatory response as an important component. Thus, ALS has paralleled other neurodegenerative disorders, such as Alzheimer's and prion diseases, in which the inflammatory process is believed to participate directly in neuronal death.