bluuebunny/crossref_metadata_2025 huggingface dataset:
The multivariate
L
1
-median and associated data depth
Authors: Vardi Yehuda , Zhang Cun-Hui
Published: July 2002

This paper gives three related results: (
i
) a new, simple, fast, monotonically converging algorithm for deriving the
L
1
-median of a data cloud in ℝ

d

, a problem that can be traced to Fermat and has fascinated applied mathematicians for over three centuries; (
ii
) a new general definition for depth functions, as functions of multivariate medians, so that different definitions of medians will, correspondingly, give rise to different dept functions; and (
iii
) a simple closed-form formula of the
L
1
-depth function for a given data cloud in ℝ

d

.
A 9-nt segment of a cellular mRNA can function as an internal ribosome entry site (IRES) and when present in linked multiple copies greatly enhances IRES activity
Authors: Chappell Stephen A. , Edelman Gerald M. , Mauro Vincent P.
Published: July 2002

This study addresses the properties of a newly identified internal ribosome entry site (IRES) contained within the mRNA of the homeodomain protein Gtx. Sequential deletions of the 5′ untranslated region (UTR) from either end did not define distinct IRES boundaries; when five nonoverlapping UTR fragments were tested, four had IRES activity. These observations are consistent with other cellular IRES analyses suggesting that some cellular IRESes are composed of segments (IRES modules) that independently and combinatorially contribute to overall IRES activity. We characterize a 9-nt IRES module from the Gtx 5′ UTR that is 100% complementary to the 18S rRNA at nucleotides 1132–1124. In previous work, we demonstrated that this mRNA segment could be crosslinked to its complement within intact 40S subunits. Here we show that increasing the number of copies of this IRES module in the intercistronic region of a dicistronic mRNA strongly enhances IRES activity in various cell lines. Ten linked copies increased IRES activity up to 570-fold in Neuro 2a cells. This level of IRES activity is up to 63-fold greater than that obtained by using the well characterized encephalomyocarditis virus IRES when tested in the same assay system. When the number of nucleotides between two of the 9-nt Gtx IRES modules was increased, the synergy between them decreased. In light of these findings, we discuss possible mechanisms of ribosome recruitment by cellular mRNAs, address the proposed role of higher order RNA structures on cellular IRES activity, and suggest parallels between IRES modules and transcriptional enhancer elements.
Acculturation and Cognitive Performance of Migrant Children in The Netherlands
Authors: van de Vijver Fons J. R. , Helms‐Lorenz Michelle , Feltzer Max J. A.
Published: July 2002

Acculturative strategies and cognitive acculturation were studied among 118 Dutch migrant children (age: 7–12 years). Both an exploratory factor analysis and a Linear Logistic Test Model analysis provided evidence for the bipolar unidimensionality of Berry's four acculturation strategies; integration constituted one pole and assimilation, separation, and marginalization the other. Integration was by far the most popular strategy. Cognitive performance was measured by the Snijders‐Oomen Nonverbal Intelligence Test, school report measures, and a computer‐assisted choice reaction‐time measure. A good fit was found for a structural model that postulated cognitive acculturation as the latent variable linking background measures (i.e. acculturation strategy, second language usage, age, and gender) to the cognitive measures. Relationships between background variables and cognitive performance were stronger in the first than in the second generation. Both older children and children who favour an integration strategy showed a higher degree of cognitive acculturation.
Asian Crisis, Financial Systems and Urban Development
Authors: Fujita Kuniko
Published: July 2002

The Asian financial crisis, which violently thwarted the east Asian miracle in the summer of 1997, has subsequently led east Asia to the building of a new financial architecture. This paper argues that the new financial architecture, modelled after the globally influential, market-centred US system, clashes with Japan's regionally active, state-centred financial system. And it explores the implications of these two financial systems for urban development in Asian capital cities. The paper concludes that Asian capital cities will do better with the state-centred financial system than with the market-centred financial system.
Self-help and Mutual Aid in Deprived Urban Neighbourhoods: Some Lessons from Southampton
Authors: Williams Colin C. , Windebank Jan
Published: July 2002

This paper evaluates self-help and mutual aid as tools for tackling social exclusion and promoting social cohesion in deprived urban neighbourhoods. Highlighting the rationales for using self-help and mutual aid to combat social exclusion and cohesion and then drawing upon case-study evidence from a deprived neighbourhood in Southampton to investigate their nature and extent as well as the barriers preventing their usage, it finds that although self-help and mutual aid are crucial and growing components of household work practices, no-earner households are unable to benefit from this work to the same extent as employed households. Consequently, the paper proposes ways in which the barriers that prevent these households from participating in such activities can be overcome.
The External Effects of Local Attributes on Living Environment in Detached Residential Blocks in Tokyo
Authors: Gao Xiaolu , Asami Yasushi
Published: July 2002

Measuring environment attributes in monetary terms is an effective approach for evaluating living environments and planning. This paper presents a study employing a hedonic pricing model on the externalities of local attributes in detached residential blocks in Tokyo. Results show that a group of local attributes, including both attributes of individual lots and of local districts, exert stable external effects. Moreover, many of these effects are changing with the size of land lot. These findings provide important information for urban planning and design in detached residential blocks. In the paper, the sub-division of land lots, an event arousing much concern in recent years, is analysed and concepts on facilitating local parks are suggested.
Intraurban Housing Mobility in a Traditional West African City: Shelter or Business Decision?
Authors: Sinai Irit
Published: July 2002

The use of housing for income generation through informal-sector activities is widespread in urban areas of developing countries. Most households consider their shelter needs when making housing choices. For households that use their dwellings for income generation, housing choices are also business decisions. Using data from a 596-household survey collected in 1996 in Kumasi, Ghana, logistic regression is used to examine the determinants of intraurban moves. Households using their home for income generation are significantly less likely to move.
Low Demand for Housing: Incidence, Causes and UK National Policy Implications
Authors: Bramley Glen , Pawson Hal
Published: July 2002

Low and falling demand for housing has come to be recognised as a fairly widespread phenomenon in late 1990s Britain. Whilst research has tended to focus on the negative consequences of this for social rented housing, the weakness of the private housing market has led to increasingly grave problems in some inner cities and former coalfields, particularly in the North of England. The main purpose of the paper is to review and evaluate the actual and potential public policy responses to this complex of issues in relation to both private- and public-sector housing, in the light of new evidence on the extent, incidence and causes of low demand. Whilst central government has displayed a growing recognition of the need to develop counter-measures, particularly in England, the paper questions whether those so far proposed fully address the severity and intractability of the issue.
A Stupendous Hammer: Colonial and Post-colonial Reconstructions of Zanzibar's Other Side
Authors: Myers Garth Andrew
Published: July 2002

Ng'ambo is the historic Other Side of Zanzibar city. The last 50 years have brought two attempts to demolish Ng'ambo and replace it with spaces designed to express the dominance of the state. Differences at first appear to be large between colonial and post-colonial Zanzibar. Yet these reconstructions shared similar objectives, failures and consequences. This paper highlights commonalities between the two projects and ties them to three themes from the literature of colonial cities in Africa concerning colonial urban planning and its post-colonial legacy. These themes include: the bureaucratisation and centralisation of power; the manipulation of space as a means of fostering hegemony; and the alienation of residents from the planning process.
Public Sector Relocation and Regional Development
Authors: Jefferson C.W. , Trainor M.
Published: July 2002

The drive for efficiency in national government has given an increased impetus to Civil Service relocation away from London and the South East. This provides opportunities for regional development similar to those in business support operations in the private sector. In assessing such opportunities, the paper looks at the economic benefits and costs of public sector relocation. The history of Civil Service relocation and the motivating factors are examined. Regional development agencies cannot offer the same inducements as do private services, but they have broadened their activities in order to attract mobile public-sector employment.
A Comparison of Canadian and American Housing Policies
Authors: Wexler Martin E.
Published: July 2002

This paper discusses the hypothesis that, despite numerous similarities between Canada and the US in terms of their history, geography, life-style, living standard and democratic form of government, there are nonetheless significant differences between the two countries' social policies that translate into differences in several of their housing and related urban policies. Here the case is made that variations in each country's approach to housing result from differences in their founding principles and from their historical experiences.
Moving and Improving: Strategies for Attaining Housing Equilibrium
Authors: Littlewood Amanda , Munro Moira
Published: July 2002

The concept of equilibrium consumption is central to much housing market analysis, yet analysts must contend with the likelihood that many housing consumers are not at an exact equilibrium level of consumption because of the inhibiting effects of the high cost of moving. This paper explores the theoretical and empirical importance of improvement activity and its relationship with residential mobility in attaining equilibrium housing consumption. The paper argues that previous frameworks have over-simplified the options available to households, by assuming that improving and moving are discrete, alternative ways of attaining an equilibrium level of consumption. Instead, the evidence presented here suggests that recent movers will frequently undertake a programme of improvement activity so that the newly acquired dwelling will, over a period of months or years, more closely match the household's requirements. This suggests that the price and quality 'bundle' chosen at the time of purchase may not, in fact, be an accurate measure of the households current or future equilibrium housing consumption.
Housing Renewal, Urban Policy and Gentrification
Authors: Bailey Nick , Robertson Douglas
Published: July 2002

Understanding the impacts of housing renewal policies has become an increasingly complex task. First, evaluation must recognise the changing urban context within which policies operate, notably the revitalisation of some inner-city areas through the process of gentrification. Secondly, and more importantly, housing renewal policies should be viewed in the wider context of urban policy. Yet competing frameworks are available for judging success in urban policy terms. These take opposing views of whether gentrification should be considered a desirable outcome. The article illustrates these points by drawing on a recent evaluation of the impacts of the Housing Action Areas programme in Scotland. It shows that contrasting approaches to implementing renewal were adopted in the two main cities and that the impacts of renewal varied as a result. Judgement of the 'success' of each approach is shown to depend upon the framework used. The findings also suggest that the state may play a major role in influencing the process of restructuring under way in many cities.
Urbanisation, Agriculture and Industrialisation in China, 1952-91
Authors: Young Denise , Deng Honghai
Published: July 2002

Urbanisation rates in China have been low compared to other countries at similar stages of development. We examine recent trends in China's urbanisation process in the context of a disequilibrium supply and demand model for urban residents with relative urban food consumption as a proxy for wages. This model takes into consideration the roles of the agricultural and industrial sectors in the context of a non-market economy where institutional arrangements and policy regimes play important roles in determining urbanisation levels. We find persistent periods of disequilibrium prior to the introduction of reforms in 1978. Throughout the post-reform era there has been a markedly improved balance between urban population levels, urban food consumption, and industrial and agricultural production levels.
Population Density in Suburban Chicago: A Bid-rent Approach
Authors: McMillen Daniel P. , McDonald John F.
Published: July 2002

Bid-rent theory suggests that the dependent variable of a population density function is unobserved (or population equals zero) if land values are relatively low in residential use. If the errors of density and bid-rent function errors are correlated, bid-rent theory implies that OLS population density estimates are subject to selection bias. Combined land use and density estimates for suburban Chicago confirm these predictions. The results provide further evidence that Chicago cannot be modelled adequately as other than a polycentric city.
Social Housing Reforms in England and Wales: A Public Choice Evaluation
Authors: Boyne George A. , Walker Richard M.
Published: July 2002

Public choice theory provides three main principles for the management of social housing: market structures should be competitive; organisations should be compelled to produce information on their efficiency and effectiveness; and large agencies should be disaggregated into smaller units. Social housing reforms in England and Wales have largely reflected these principles. However, it is difficult to establish the impact of public choice policies because data on housing performance are incomplete. Furthermore, the effects of housing reforms are clouded by a range of social and economic changes in the context of housing management. Nevertheless, the available evidence suggests that public choice principles have had contradictory effects: efficiency and responsiveness have improved, but equity has deteriorated. Thus judgements on public choice theory depend on the weight attached to these different dimensions of performance.
The District Effect and the Competitiveness of Manufacturing Companies in Local Productive Systems
Authors: Costa-Campi M. Teresa , Viladecans-Marsal Elisabet
Published: July 2002

The present study evaluates the existence of differences in competitiveness of Spanish industrial firms as a consequence of the district effect. A quantitative analysis has been performed in order to assess external competitiveness taking into account whether firms are located in industrial districts—in the sense proposed by Marshall-Becattini—or remain isolated. The methodological approach considers geographical and sectoral variables. It attempts to establish the existence of a relationship between sectoral specialisation and business efficiency— measured as the capacity to export—in local productive systems. Most of the variables come from a 1991 fiscal data-set and the territorial units of analysis are 332 municipalities with a population of over 15 000 inhabitants. From the results on the econometric model, it can be inferred that the geographical concentration of companies in the same activity positively influences their level of competitiveness.
Social Housing Finance in Europe: Trends and Opportunities
Authors: Priemus Hugo , Boelhouwer Peter
Published: July 2002

The central topic of this contribution is the financing of the social rented sector in seven countries in western Europe: the Netherlands, Belgium, Denmark, Germany, Great Britain, France and Sweden. Since 1975, the macro housing quota has increased in all seven countries, but most of all in the Netherlands. Property subsidies have been reduced; housing allowances have become more important. The differences in size of the social rented sector remain large. Private finance has mostly replaced public loans, with the exception of Germany where interest-free government loans cover part of the finance needed. In most countries, guarantees for capital market loans exist, Great Britain being the exception. In the near future, changes in social housing finance may be expected as a result of European monetary integration. The euro will (for the time being) not be introduced in Denmark, Great Britain and Sweden. The costs of capital may decline when social housing finance becomes more internationalised.
The Provision of Finance for Social Housing: The UK Experience
Authors: Whitehead Christine M. E.
Published: July 2002

This paper reviews the mechanisms by which the British government has introduced private finance into the provision of housing for lower-income households. It clarifies the range of measures that have allowed transfers from social to private ownership, both into owner-occupation and to independent landlords. However, the main thrust of the paper is an examination of the approach to introducing private finance into new social provision undertaken by housing associations. It examines the range of institutions that have been prepared to provide finance, the terms and conditions on which funds have been made available and the impact that private funding has had on associations' operations and viability. Finally, the paper assesses the condition under which it has been possible to fund social housing through the private market and some of the concerns that this raises for future funding possibilities.
Institutional Structure of Social Housing Finance in the UK: Recent Developments
Authors: Oxley Michael
Published: July 2002

It is argued that social housing in the UK currently faces affordability and investment problems. Rental payments are highly dependent on housing benefits and more investment, with higher rent levels and lower direct subsidy, requires more expenditure on housing benefits if affordability problems are to be avoided. The increasing role of private finance in funding housing association developments is reviewed. There is an examination of the institutional relationship between social housing expenditure and the public deficit. The case for new forms of social housing organisations which are less restricted by public expenditure controls is examined. It is argued that new social housing institutions will contribute more to the resolution of the investment than the affordability problem. The relationship between finance and social purpose is explored. It is concluded that there is a continuing need for redistributive measures if social housing is to achieve its essential purposes.
A Comparison of Middle Class English-Canadian and Italian Mothers’ Beliefs about Children’s Peer-directed Aggression and Social Withdrawal
Authors: Schneider Barry H. , Attili Grazia , Vermigli Patrizia , Younger Alastair
Published: July 2002

Middle class mothers of 7-year-olds in Canada and Italy were presented hypothetical scenarios depicting children being aggressive or socially withdrawn. The mothers were asked to indicate how they thought the behaviour was caused, how they would feel if their child displayed it, and what socialisation strategies they would use in reacting to it. Most mothers in both countries indicated that they would resort to moderate to high levels of power assertion in response to children’s aggressive behaviour and responses of low to moderate power in cases of children’s social withdrawal. The Canadian mothers indicated that they would experience generally stronger emotional responses with regard to both types of problematic social behaviour in children. Italian mothers indicated that they would use lower levels of power in response to social withdrawal of girls than boys. These results are considered in the light of known differences in value placed on individual initiative between the two countries, and national differences in gender role expectations.
Regional Development
Authors: Gaffikin Frank , Morrissey Mike
Published: July 2002

This article addresses regional development in a con tested society, examining the extent to which the main region al strategies in Northern Ireland form an integrated approach to resolving not only the structural weaknesses in the economy, but also the outcomes of the socio-spatial segregation attendant upon the ethno-nationalist conflict. From this analysis, it proposes a model of regional development that transcends the traditional ‘auction’ approach, whereby sub-regions view themselves as rivals in bids for development opportunities. The argument is advanced that the twinning of the processes of regeneration and reconciliation is essential to long-term progress.
Developmental Effects and Health Aspects of Soy Protein Isolate, Casein, and Whey in Male and Female Rats
Authors: Badger Thomas M. , Ronis Martin J. J. , Hakkak Reza
Published: July 2002

Dietary factors other than the traditional nutrients are found in the so-called functional foods. They are becoming increasingly recognized as potentially important for maintaining good health. Soybeans are rich in such factors thought to help prevent certain chronic diseases. Soy protein isolate (SPI) is one of the three major proteins used in infant formulas sold in the United States, with casein (CAS) and whey (WPH) proteins being the others. We have been studying the health effects of these proteins. Safety concerns have developed over the consumption of soy-based infant formula, partly because of the high circulating levels of the total isoflavones (phytoestrogens) during “critical periods of infant development.” There is a paucity of data on developmental, physiological, neurophysiological, behavioral, metabolic, or molecular effects of soy phytochemicals in humans, especially during pregnancy and infancy. We have studied the effects of CAS, SPI, and WPH in short-term, long-term, and multigenerational studies in rats. Aside from minor differences in body weight gain profiles, CAS-, SPI-or WPH-fed rats did not differ in development, organ weights, in vitro hepatic metabolism of testosterone (T), or reproductive performance. However, some endocrine-related functions differed between rats fed these proteins. We found that SPI accelerated puberty in female rats ( p <.05) and WPH delayed puberty in males and females, as compared with CAS ( p <.05). Gender differences were also found in gonadectomy-induced steroid responses. Male rats had normal serum T levels, but female rats fed SPI had reduced serum 17β-estradiol concentrations and a blunted 17β-estradiol response to ovariectomy, as compared to rats fed CAS or WHP ( p <.05). Female rats fed SPI or WHP or treated with genistein had reduced incidence of chemically induced mammary cancers ( p <.05) compared to CAS controls, with WHP reducing tumor incidence by as much as 50%, findings that replicate previous results from our laboratory. Together, these results suggest gender-specific differences in development and certain endocrine responses among rats fed diets composed of a single protein source such as those used in infant formulas. Whether similar developmental effects occur in human infants is unknown, but unlikely because (1) most infants do not consume such diets throughout life as these rats did, and (2) no such effects have been reported in millions of American infants fed infant formula containing these proteins. The long-term health consequence implications of early diet exposure to SPI and WPH, such as reduced breast cancer incidence, are likely to be very positive.
Lack of Oncogenicity of Wood Creosote, the Principal Active Ingredient of Seirogan, an Herbal Antidiarrheal Medication, in Sprague-Dawley Rats
Authors: Kuge Tomoo , Shibata Takashi , Willett Michael S. , Turck Patricia , Traul Karl A.
Published: July 2002

Seirogan, an herbal medicine containing wood creosote (tablets, 10.0% w/w), has been developed and marketed for almost a century in various countries for the control of acute diarrhea and treatment of associated symptoms, such as abdominal cramping. Wood creosote (CAS no. 8021–39–4) is a mixture of simple phenolic compounds, including guaiacol and creosol and related compounds, and is chemically distinct from, and should not be confused with, coal tar creosote, a known carcinogen. In the current study, the oncogenic potential of wood creosote was assessed in a 96/103-week oral gavage study in Sprague-Dawley rats. Groups of 60 rats/sex received wood creosote at dose levels of 20, 50, or 200 mg/kg body weight [bw]/day. An additional group of rats received the vehicle, 0.5% carboxymethylcellulose in deionized, distilled water, at the same dose volume as the treatment groups (10 ml/kg) and served as the controls. Treatment-related decreases in survival, body weight, and food consumption, as well as increased incidences of clinical signs that included rales, decreased activity, and salivation, were noted at 200 mg/kg bw/day when compared with the control group. There was an increased incidence of reddened and edematous lungs in rats from the 200 mg/kg bw/day group that died during the study. The lung findings were suggestive of test article aspiration during dose administration or agonal aspiration preceding and possibly resulting in death, especially because these observations were not seen in animals that survived to scheduled sacrifice. Additionally, phenols are generally recognized as having corrosive properties. There were no changes in clinical pathology and no increases in neoplastic or non-neoplastic lesions, excluding the lung findings, related to treatment with wood creosote at any dose level. Although the results of this study indicate that the maximum tolerated dose of wood creosote was met or exceeded at 200 mg/kg bw/day, there was no evidence of oncogenicity at any dose level. The lack of any evidence of oncogenicity supports the safety profile of the active ingredient in Seirogan, wood creosote.
Characterization of Hydronephrosis in Neonatal Rats from Dams Receiving Candesartan Cilexetil (TCV-116), an Angiotensin II Type 1 Receptor Antagonist
Authors: Ishimura Yoshimasa , Chatani Fumio , Sato Shuzo
Published: July 2002

The characteristics and mechanisms of hydronephrosis in neonatal rats induced by candesartan cilexetil (TCV-116), a potent angiotensin II (AngII) type 1 receptor antagonist, were examined. TCV-116 (300 mg/kg/day) was orally administered to dams for 4 weeks from gestation day 15 through lactation day 21. On lactation days 0, 4, 7, 14, and 22, the kidneys of the pups were examined. Hydronephrosis was observed starting on lactation day 14 accompanied by other histological changes, atrophy of the renal papillary tubules, dilatation of the renal tubules, and basophilic renal tubules in the cortex. These changes could also be observed at 10 weeks of age, 7 weeks after the last dose was administered. These renal structural abnormalities were consistent with that seen in other renin-angiotensin system antagonists. TCV-116 (300 mg/kg/day) was then administered to dams for four separate 1-week periods: gestation days 15 through 21, lactation days 0 to 6, lactation days 7 to 13, and lactation days 14 to 21. Pups were most susceptible to the induction of hydronephrosis when TCV-116 was administered from lactation days 0 to 6 and lactation days 7 to 13. The increased incidence of hydronephrosis and renal histological changes in the pups was prevented by administering mineralocorticoid, deoxycorticosterone acetate (10 mg/kg/day), subcutaneously to the pups from lactation days 7 to 13. Also, plasma aldosterone concentration in the pups was decreased after three daily treatments of TCV-116, accompanied by the increased plasma potassium concentration and urine Na/K ratio and the decreased urine osmolality. Therefore, we considered that the development of hydronephrosis in pups is closely related to the AngII blockade for the first 2 weeks after birth, and the reduction of aldosterone secretion by the inhibition of AngII leads to the disorder of the sodium and potassium homeostasis in neonates, and subsequent increase in urine volume may be involved in the mechanisms of hydronephrosis. We conclude that the hydronephrosis was caused by the sodium imbalance resulted from the pharmacological action of TCV-116 during the neonatal period.
Studies of Strain Differences in the Spontaneous and Induced Frequencies of Cells Resistant to Calcium-Induced Terminal Differentiation
Authors: Przygoda Robert T. , McKee Richard H. , Freeman James J. , Plutnick Robert T. , Nicolich Mark J. , Katz Stanley
Published: July 2002

C3H mice were found to be much less responsive to tumor induction in an initiation/promotion protocol than CD-I mice. To explore the difference in strain sensitivity, the frequencies of cells resistant to calcium-induced terminal differentiation(calcium resistant cells, CRCs) were measured in C3H, CD-I, and SENCAR mice. The induced frequencies after 7,12-dimethylbenz(a)anthracene(DMBA) treatment were similar in all three strains, ranging from 0.70 to 0.83 × 10-6, and suggested that the differences in tumor outcome were more likely related to promotion than initiation. Spontaneous frequencies ranged from 0.73 to 3.75 CRCs per mouse or 0.07 to 0.22 CRC/106 cells. The spontaneous frequency in the C3H mouse was significantly less than that in the other two strains. However, the spontaneous mutation rates were found to be similar in all three strains, ranging from 0.05 to 0.07 × 10-6 and it was found that the keratinocytes, which were resistant to terminal differentiation, were independently distributed in C3H but not in CD-I and SENCAR mice. These data are consistent with the hypothesis that clonal expansion occurs in CD-I and SENCAR but not C3H mice. Conceivably the greater propensity for clonal expansion in CD-I and SENCAR than in C3H mice is related to the greater likelihood of tumor formation as well as the more rapid development of tumors in the former strains.
Progressive Kidney Degeneration in Mice Lacking Tensin
Authors: Lo Su Hao , Yu Qian-Chun , Degenstein Linda , Chen Lan Bo , Fuchs Elaine
Published: July 2002

Tensin is a focal adhesion phosphoprotein that binds to F-actin and contains a functional Src homology 2 domain. To explore the biological functions of tensin, we cloned the mouse tensin gene, determined its program of expression, and used gene targeting to generate mice lacking tensin. Even though tensin is expressed in many different tissues during embryogenesis, tensin null mice developed normally and appeared healthy postnatally for at least several months. Over time, −/− mice became frail because of abnormalities in their kidneys, an organ that expresses high levels of tensin. Mice with overt signs of weakness exhibited signs of renal failure and possessed multiple large cysts in the proximal kidney tubules, but even in tensin null mice with normal blood analysis, cysts were prevalent. Ultrastructurally, noncystic areas showed typical cell– matrix junctions that readily labeled with antibodies against other focal adhesion molecules. In abnormal regions, cell–matrix junctions were disrupted and tubule cells lacked polarity. Taken together, our data imply that, in the kidney, loss of tensin leads to a weakening, rather than a severing, of focal adhesion. All other tissues appeared normal, suggesting that, in most cases, tensin's diverse functions are redundant and may be compensated for by other focal adhesion proteins.
Mitochondrial Proliferation and Paradoxical Membrane Depolarization during Terminal Differentiation and Apoptosis in a Human Colon Carcinoma Cell Line
Authors: Mancini Mariangela , Anderson Benjamin O. , Caldwell Elizabeth , Sedghinasab Monireh , Paty Philip B. , Hockenbery David M.
Published: July 2002

Herbimycin A, a tyrosine kinase inhibitor, induces cellular differentiation and delayed apoptosis in Colo-205 cells, a poorly differentiated human colon carcinoma cell line. Cell cycle analysis in conjunction with end labeling of DNA fragments revealed that G2 arrest preceded apoptotic cell death. Ultrastructural examination of herbimycin-treated cells demonstrated morphologic features of epithelial differentiation, including formation of a microvillar apical membrane and lateral desmosome adhesions. A marked accumulation of mitochondria was also observed. Fluorometric analysis using the mitochondrial probes nonyl-acridine orange and JC-1 confirmed a progressive increase in mitochondrial mass. However these cells also demonstrated a progressive decline in unit mitochondrial transmembrane potential (ΔΨm) as determined by the ΔΨm-sensitive fluorescent probes rhodamine 123 and JC-1 analyzed for red fluorescence. In concert with these mitochondrial changes, Colo-205 cells treated with herbimycin A produced increased levels of reactive oxygen species as evidenced by oxidation of both dichlorodihydrofluorescein diacetate and dihydroethidium. Cell-free assays for apoptosis using rat-liver nuclei and extracts of Colo-205 cells at 24 h showed that apoptotic activity of Colo-205 lysates requires the early action of mitochondria. Morphological and functional mitochondrial changes were observed at early time points, preceding cleavage of poly (ADP-ribose) polymerase.

These results suggest that apoptosis in differentiated Colo-205 cells involves unrestrained mitochondrial proliferation and progressive membrane dysfunction, a novel mechanism in apoptosis.
A Correlative Analysis of Actin Filament Assembly, Structure, and Dynamics
Authors: Steinmetz Michel O. , Goldie Kenneth N. , Aebi Ueli
Published: July 2002

The effect of the type of metal ion (i.e., Ca2+, Mg2+, or none) bound to the high-affinity divalent cation binding site (HAS) of actin on filament assembly, structure, and dynamics was investigated in the absence and presence of the mushroom toxin phalloidin. In agreement with earlier reports, we found the polymerization reaction of G-actin into F-actin filaments to be tightly controlled by the type of divalent cation residing in its HAS. Moreover, novel polymerization data are presented indicating that LD, a dimer unproductive by itself, does incorporate into growing F-actin filaments. This observation suggests that during actin filament formation, in addition to the obligatory nucleation– condensation pathway involving UD, a productive filament dimer, a facultative, LD-based pathway is implicated whose abundance strongly depends on the exact polymerization conditions chosen. The “ragged” and “branched” filaments observed during the early stages of assembly represent a hallmark of LD incorporation and might be key to producing an actin meshwork capable of rapidly assembling and disassembling in highly motile cells. Hence, LD incorporation into growing actin filaments might provide an additional level of regulation of actin cytoskeleton dynamics. Regarding the structure and mechanical properties of the F-actin filament at steady state, no significant correlation with the divalent cation residing in its HAS was found. However, compared to native filaments, phalloidin-stabilized filaments were stiffer and yielded subtle but significant structural changes. Together, our data indicate that whereas the G-actin conformation is tightly controlled by the divalent cation in its HAS, the F-actin conformation appears more robust than this variation. Hence, we conclude that the structure and dynamics of the Mg–F-actin moiety within the thin filament are not significantly modulated by the cyclic Ca2+ release as it occurs in muscle contraction to regulate the actomyosin interaction via troponin.
p28 Bap31, a Bcl-2/Bcl-XL- and Procaspase-8–associated Protein in the Endoplasmic Reticulum
Authors: Ng Florence W.H. , Nguyen Mai , Kwan Tony , Branton Philip E. , Nicholson Donald W. , Cromlish James A. , Shore Gordon C.
Published: July 2002

We have identified a human Bcl-2–interacting protein, p28 Bap31. It is a 28-kD (p28) polytopic integral protein of the endoplasmic reticulum whose COOH-terminal cytosolic region contains overlapping predicted leucine zipper and weak death effector homology domains, flanked on either side by identical caspase recognition sites. In cotransfected 293T cells, p28 is part of a complex that includes Bcl-2/Bcl-XL and procaspase-8 (pro-FLICE). Bax, a pro-apoptotic member of the Bcl-2 family, does not associate with the complex; however, it prevents Bcl-2 from doing so. In the absence (but not presence) of elevated Bcl-2 levels, apoptotic signaling by adenovirus E1A oncoproteins promote cleavage of p28 at the two caspase recognition sites. Purified caspase-8 (FLICE/MACH/Mch5) and caspase-1(ICE), but not caspase-3 (CPP32/apopain/ Yama), efficiently catalyze this reaction in vitro. The resulting NH2-terminal p20 fragment induces apoptosis when expressed ectopically in otherwise normal cells. Taken together, the results suggest that p28 Bap31 is part of a complex in the endoplasmic reticulum that mechanically bridges an apoptosis-initiating caspase, like procaspase-8, with the anti-apoptotic regulator Bcl-2 or Bcl-XL. This raises the possibility that the p28 complex contributes to the regulation of procaspase-8 or a related caspase in response to E1A, dependent on the status of the Bcl-2 setpoint within the complex.
The Tim54p–Tim22p Complex Mediates Insertion of Proteins into the Mitochondrial Inner Membrane
Authors: Kerscher Oliver , Holder Jason , Srinivasan Maithreyan , Leung Roxanne S. , Jensen Robert E.
Published: July 2002

We have identified a new protein, Tim54p, located in the yeast mitochondrial inner membrane. Tim54p is an essential import component, required for the insertion of at least two polytopic proteins into the inner membrane, but not for the translocation of precursors into the matrix. Several observations suggest that Tim54p and Tim22p are part of a protein complex in the inner membrane distinct from the previously characterized Tim23p-Tim17p complex. First, multiple copies of the TIM22 gene, but not TIM23 or TIM17, suppress the growth defect of a tim54-1 temperature-sensitive mutant. Second, Tim22p can be coprecipitated with Tim54p from detergent-solubilized mitochondria, but Tim54p and Tim22p do not interact with either Tim23p or Tim17p. Finally, the tim54-1 mutation destabilizes the Tim22 protein, but not Tim23p or Tim17p. Our results support the idea that the mitochondrial inner membrane carries two independent import complexes: one required for the translocation of proteins across the inner membrane (Tim23p–Tim17p), and the other required for the insertion of proteins into the inner membrane (Tim54p–Tim22p).
Ultraviolet Light Induces Apoptosis via Direct Activation of CD95 (Fas/APO-1) Independently of Its Ligand CD95L
Authors: Aragane Yoshinori , Kulms Dagmar , Metze Dieter , Wilkes Gabriele , Pöppelmann Birgit , Luger Thomas A. , Schwarz Thomas
Published: July 2002

Induction of apoptosis in keratinocytes by UV light is a critical event in photocarcinogenesis. Although p53 is of importance in this process, evidence exists that other pathways play a role as well. Therefore, we studied whether the apoptosis-related surface molecule CD95 (Fas/APO-1) is involved. The human keratinocyte cell line HaCaT expresses CD95 and undergoes apoptosis after treatment with UV light or with the ligand of CD95 (CD95L). Incubation with a neutralizing CD95 antibody completely prevented CD95L-induced apoptosis but not UV-induced apoptosis, initially suggesting that the CD95 pathway may not be involved. However, the protease CPP32, a downstream molecule of the CD95 pathway, was activated in UV-exposed HaCaT cells, and UV-induced apoptosis was blocked by the ICE protease inhibitor zVAD, implying that at least similar downstream events are involved in CD95- and UV-induced apoptosis. Activation of CD95 results in recruitment of the Fas-associated protein with death domain (FADD) that activates ICE proteases. Immunoprecipitation of UV-exposed HaCaT cells revealed that UV light also induces recruitment of FADD to CD95. Since neutralizing anti-CD95 antibodies failed to prevent UV-induced apoptosis, this suggested that UV light directly activates CD95 independently of the ligand CD95L. Confocal laser scanning microscopy showed that UV light induced clustering of CD95 in the same fashion as CD95L. Prevention of UV-induced CD95 clustering by irradiating cells at 10°C was associated with a significantly reduced death rate. Together, these data indicate that UV light directly stimulates CD95 and thereby activates the CD95 pathway to induce apoptosis independently of the natural ligand CD95L. These findings further support the concept that UV light can affect targets at the plasma membrane, thereby even inducing apoptosis.
Effects of Forced Expression of an NH2-terminal Truncated β-Catenin on Mouse Intestinal Epithelial Homeostasis
Authors: Wong Melissa H. , Rubinfeld Bonnee , Gordon Jeffrey I.
Published: July 2002

β-Catenin functions as a downstream component of the Wnt/Wingless signal transduction pathway and as an effector of cell–cell adhesion through its association with cadherins. To explore the in vivo effects of β-catenin on proliferation, cell fate specification, adhesion, and migration in a mammalian epithelium, a human NH2-terminal truncation mutant (ΔN89β-catenin) was expressed in the 129/Sv embryonic stem cell–derived component of the small intestine of adult C57Bl/6–ROSA26↔ 129/Sv chimeric mice. ΔN89β-Catenin was chosen because mutants of this type are more stable than the wild-type protein, and phenocopy activation of the Wnt/Wingless signaling pathway in Xenopus and Drosophila. ΔN89β-Catenin had several effects. Cell division was stimulated fourfold in undifferentiated cells located in the proliferative compartment of the intestine (crypts of Lieberkühn). The proliferative response was not associated with any discernible changes in cell fate specification but was accompanied by a three- to fourfold increase in crypt apoptosis. There was a marked augmentation of E-cadherin at the adherens junctions and basolateral surfaces of 129/Sv (ΔN89β-catenin) intestinal epithelial cells and an accompanying slowing of cellular migration along crypt-villus units. 1–2% of 129/Sv (ΔN89β-catenin) villi exhibited an abnormal branched architecture. Forced expression of ΔN89β-catenin expression did not perturb the level or intracellular distribution of the tumor suppressor adenomatous polyposis coli (APC). The ability of ΔN89β-catenin to interact with normal cellular pools of APC and/or augmented pools of E-cadherin may have helped prevent the 129/Sv gut epithelium from undergoing neoplastic transformation during the 10-mo period that animals were studied. Together, these in vivo studies emphasize the importance of β-catenin in regulating normal adhesive and signaling functions within this epithelium.
Defining the Interactions Between Intermediate Filaments and Desmosomes
Authors: Smith Elizabeth A. , Fuchs Elaine
Published: July 2002

Desmoplakin (DP), plakoglobin (PG), and plakophilin 1 (PP1) are desmosomal components lacking a transmembrane domain, thus making them candidate linker proteins for connecting intermediate filaments and desmosomes. Using deletion and site-directed mutagenesis, we show that remarkably, removal of ∼1% of DP's sequence obliterates its ability to associate with desmosomes. Conversely, when linked to a foreign protein, as few as 86 NH2-terminal DP residues are sufficient to target to desmosomes efficiently. In in vitro overlay assays, the DP head specifically associates with itself and with desmocollin 1a (Dsc1a). In similar overlay assays, PP1 binds to DP and Dsc1a, and to a lesser extent, desmoglein 1 (Dsg1), while PG binds to Dsg1 and more weakly to Dsc1a and DP. Interestingly, like DP, PG and PP1 associate with epidermal keratins, although PG is considerably weaker in its ability to do so. As judged by overlay assays, the amino terminal head domain of type II keratins appears to have a special importance in establishing these connections. Taken together, our findings provide new insights into the complexities of the links between desmosomes and intermediate filaments (IFs). Our results suggest a model whereby at desmosome sites within dividing epidermal cells, DP and PG anchor to desmosomal cadherins and to each other, forming an ordered array of nontransmembrane proteins that then bind to keratin IFs. As epidermal cells differentiate, PP1 is added as a molecular reinforcement to the plaque, enhancing anchorage to IFs and accounting at least partially for the increase in numbers and stability of desmosomes in suprabasal cells.
An Atypical PKC Directly Associates and Colocalizes at the Epithelial Tight Junction with ASIP, a Mammalian Homologue of Caenorhabditis elegans Polarity Protein PAR-3
Authors: Izumi Yasushi , Hirose Tomonori , Tamai Yoko , Hirai Syu-ichi , Nagashima Yoji , Fujimoto Toyoshi , Tabuse Yo , Kemphues Kenneth J. , Ohno Shigeo
Published: July 2002

Cell polarity is fundamental to differentiation and function of most cells. Studies in mammalian epithelial cells have revealed that the establishment and maintenance of cell polarity depends upon cell adhesion, signaling networks, the cytoskeleton, and protein transport. Atypical protein kinase C (PKC) isotypes PKCζ and PKCλ have been implicated in signaling through lipid metabolites including phosphatidylinositol 3-phosphates, but their physiological role remains elusive. In the present study we report the identification of a protein, ASIP (atypical PKC isotype–specific interacting protein), that binds to aPKCs, and show that it colocalizes with PKCλ to the cell junctional complex in cultured epithelial MDCKII cells and rat intestinal epithelia. In addition, immunoelectron microscopy revealed that ASIP localizes to tight junctions in intestinal epithelial cells. Furthermore, ASIP shows significant sequence similarity to Caenorhabditis elegans PAR-3. PAR-3 protein is localized to the anterior periphery of the one-cell embryo, and is required for the establishment of cell polarity in early embryos. ASIP and PAR-3 share three PDZ domains, and can both bind to aPKCs. Taken together, our results suggest a role for a protein complex containing ASIP and aPKC in the establishment and/or maintenance of epithelial cell polarity. The evolutionary conservation of the protein complex and its asymmetric distribution in polarized cells from worm embryo to mammalian-differentiated cells may mean that the complex functions generally in the organization of cellular asymmetry.