bluuebunny/crossref_metadata_2025 huggingface dataset:
An integrated model for melanocyte‐specific gene expression and melanogenesis
Authors: Emir Uzay Emrah , Kurnaz Is¸ıl Aksan
Published: March 2004

The steady increase in the incidence of cutaneous (skin) malignant melanoma worldwide generates the necessity to understand the key molecular events underlying melanogenesis and melanoma. Melanogenesis has two main stages: immediate pigmentation occurs through the redistribution of pigment‐containing melanosomes to the dendrites of melanocytes, and subsequently to the surrounding keratinocytes, without the need for any new melanin synthesis. The effect is therefore subtle and transient. Delayed and sustained tanning, however, requires (a) an increase in melanocyte number and dendricity, (b) an increase in melanosome number, and (c) an increase in melanin content. This computer‐based model focuses on the sustained eumelanin (black/brown pigment) production through melanocyte‐specific gene expression in response to external stimulus. We find in our model that high levels of melanin can be reached within an hour of stimulation. Furthermore we successfully show metabolic downregulation of pigment synthesis through employing in our simulations an experimentally‐described inhibitor for melanogenic enzymes. We see this model as a starting point for in silico drug screening for skin lightening agents, sun‐tanning agents, and eventually for anti‐melanoma agents that are under development.
Epidemiology, co‐morbidity, and impact on health‐related quality of life of self‐reported headache and musculoskeletal pain—a gender perspective
Authors: Bingefors Kerstin , Isacson Dag
Published: March 2004

Background. Headache and musculo‐skeletal pain are major public health problems. Substantial proportions of the general population report that they experience pain problems that affect their work, daily living and social life. Epidemiological studies have consistently shown that the prevalence of most pain conditions is higher in women than in men.

Design. Cross‐sectional survey in the county of Uppland, Sweden, 1995. Five thousand four hundred and four completed the questionnaire (response rate=68%). In these analyses for persons aged 20–64 years 4506 were included.

Results. Back pain (22.7%) and shoulder pain (21.0%) were the most commonly reported medical problems in the population with pain in arms/legs (15.7%) in fifth and headache (12.5%) in eight place. Major gender differences were found. The prevalence of pain conditions, especially headache, was higher among women. Women reported more severe pain. Co‐morbidity between pain conditions and psychiatric and somatic problems was higher among women. Health‐related quality of life (SF‐36) differed by gender and type of pain condition. The physical dimensions of HRQoL were more affected by headache among men; psychological dimensions were more affected among women. Among both men and women, pain conditions were associated with poorer socioeconomic conditions and life‐style factors but there were gender differences. Education and unemployment were important only among men while economical difficulties, half‐time work and being married were associated with pain among women. Obesity, early disability retirement, long time sick‐leave and lack of exercise were associated with pain conditions generally. Factors associated with pain conditions were unevenly distributed between genders.

Conclusion. There are major differences between men and women in the prevalence and severity of self‐reported pain in the population. Biological factors may explain some of the differences but the main explanation is presumably gender disparities in work, economy, daily living, social life and expectations between women and men. Although improved working conditions are of importance, deeper societal changes are needed to reduce the inequities in pain experiences between women and men.
Perceptual measures of performance: fact or fiction?
Authors: Ketokivi Mikko A , Schroeder Roger G
Published: March 2004

In contrast with the general management and strategy literature, performance measurement in the extant empirical operations management literature has relied heavily on perceptual measures of operational and financial performance. At the same time, rigorous examinations of the psychometric properties of such performance measurements instruments have not been performed. Especially needed are examinations of systematic informant bias and the related method variance and method bias, which are not captured by conventional methods used in operations management to assess construct reliability and validity. We conduct a multitrait–multimethod analysis of perceptual performance measures to investigate item‐specific trait, method and error variance. Data from 164 factories with three informants per factory is analyzed. We find that while random error and systematic bias account for a large portion of item variance, perceptual measures satisfy the requirements of reliability and validity. However, we caution against the use of single‐informant studies in future research as substantive conclusions may be affected.
The use of OP‐1 in femoral impaction grafting in a sheep model
Authors: McGee Margaret A. , Findlay David M. , Howie Donald W. , Carbone Angelo , Ward Peter , Stamenkov Roumen , Page Tara T. , Bruce Warrick J. , Wildenauer Corinna I. , Toth Carol
Published: March 2004

The aim of this pilot study was to examine bone graft incorporation in femurs impacted with allograft bone alone (control group) or with allograft containing the bone morphogenetic protein OP‐1 (BMP‐7) (OP‐1 group) in a sheep model of cemented hemiar‐throplasty. Two sheep in each group were sacrificed at 6, 18 and 26 weeks. Successful bone graft incorporation was evident in both groups by six weeks but in the OP‐1 group, there had been more extensive resorption of the graft. There was one case of excessive stem subsidence in the OP‐1 group at six weeks. By 18 weeks, there was remodelling and trabeculation of the new bone in the OP‐1 group, but this appeared less advanced in the control group. By 26 weeks, there was remodelling of bone in the graft bed. The results of this small study suggest that OP‐1 promotes initial graft resorption, thus hastening bone graft incorporation and remodelling in femoral impaction grafting. The one case of stem subsidence may be associated with the early resorption seen in the OP‐1 group and reinforces the need for further studies, examining dose response and using precise measures of stem movement, before this BMP is used in femoral impaction grafting at revision hip arthroplasty. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
An 8000-year record of vegetation, climate, and human disturbance from the Sierra de Apaneca, El Salvador
Authors: Dull Robert A.
Published: March 2004

An ∼8000-cal-yr stratigraphic record of vegetation change from the Sierra de Apaneca, El Salvador, documents a mid-Holocene warm phase, followed by late Holocene cooling. Pollen evidence reveals that during the mid-Holocene (∼8000–5500 cal yr B.P.) lowland tropical plant taxa were growing at elevations ∼200–250 m higher than at present, suggesting conditions about 1.0°C warmer than those prevailing today. Cloud forest genera (Liquidambar,Juglans,Alnus,Ulmus) were also more abundant in the mid-Holocene, indicating greater cloud cover during the dry season. A gradual cooling and drying trend began by ∼5500 cal yr B.P. culminating in the modern forest composition by ∼3500 cal yr B.P. A rise in pollen from weedy plant taxa associated with agriculture occurred ∼5000 cal yr B.P. and pollen fromZeafirst appeared in the record at ∼4440 cal yr B.P. Human impacts on local vegetation remained high throughout the late Holocene, but decreased abruptly following the Tierra Blanca Joven (TBJ) eruption of Volcán Ilopango at ∼1520 cal yr B.P. The past 1500 years are marked by higher lake levels and periodic depositions of exogenous inorganic sediments, perhaps indicating increased climatic variability.
The arrestin‐bound conformation and dynamics of the phosphorylated carboxy‐terminal region of rhodopsin
Authors: Kisselev Oleg G. , McDowell J.Hugh , Hargrave Paul A.
Published: March 2004

Visual arrestin binds to the phosphorylated carboxy‐terminal region of rhodopsin to block interactions with transducin and terminate signaling in the rod photoreceptor cells. A synthetic seven‐phospho‐peptide from the C‐terminal region of rhodopsin, Rh(330–348), has been shown to bind arrestin and mimic inhibition of signal transduction. In this study, we examine conformational changes in this synthetic peptide upon binding to arrestin by high‐resolution proton nuclear magnetic resonance (NMR). We show that the peptide is completely disordered in solution, but becomes structured upon binding to arrestin. A control, unphosphorylated peptide that fails to bind to arrestin remains highly disordered. Specific NMR distance constraints are used to model the arrestin‐bound conformation. The models suggest that the phosphorylated carboxy‐terminal region of rhodopsin, Rh(330–348), undergoes significant conformational changes and becomes structured upon binding to arrestin.
Hemifluorinated surfactants: a non‐dissociating environment for handling membrane proteins in aqueous solutions?
Authors: Breyton Cécile , Chabaud Elodie , Chaudier Yann , Pucci Bernard , Popot Jean-Luc
Published: March 2004

The instability of membrane proteins in detergent solution can generally be traced to the dissociating character of detergents and often correlates with delipidation. We examine here the possibility of substituting detergents, after membrane proteins have been solubilized, with non‐detergent surfactants whose hydrophobic moiety contains a perfluorinated region that makes it lipophobic. In order to improve its affinity for the protein surface, the fluorinated chain is terminated by an ethyl group. Test proteins included bacteriorhodopsin, the cytochrome b
6
f complex, and the transmembrane region of the bacterial outer membrane protein OmpA. All three proteins were purified using classical detergents and transferred into solutions of C2H5C6F12C2H4‐S‐poly‐Tris‐(hydroxymethyl)aminomethane (HF‐TAC). Transfer to HF‐TAC maintained the native state of the proteins and prevented their precipitation. Provided the concentration of HF‐TAC was high enough, HF‐TAC/membrane protein complexes ran as single bands upon centrifugation in sucrose gradients. Bacteriorhodopsin and the cytochrome b
6
f complex, both of which are detergent‐sensitive, exhibited increased biochemical stability upon extended storage in the presence of a high concentration of HF‐TAC as compared to detergent micelles. The stabilization of cytochrome b
6
f is at least partly due to a better retention of protein‐bound lipids.
New insights into the structure and oligomeric state of the bacterial multidrug transporter EmrE: an unusual asymmetric homo‐dimer
Authors: Ubarretxena-Belandia I , Tate C.G
Published: March 2004

EmrE is a small multidrug transporter that contains 110 amino acid residues that form four transmembrane α‐helices. The three‐dimensional structure of EmrE has been determined from two‐dimensional crystals by electron cryo‐microscopy. EmrE is an asymmetric homo‐dimer with one substrate molecule bound in a chamber accessible laterally from one leaflet of the lipid bilayer. Evidence from substrate binding analyses and analytical ultracentrifugation of detergent‐solubilised EmrE shows that the minimum functional unit for substrate binding is a dimer. However, it is possible that EmrE exists as a tetramer in vivo and plausible models are suggested based upon analyses of two‐dimensional crystals.
The first plant type III polyketide synthase that catalyzes formation of aromatic heptaketide
Authors: Abe Ikuro , Utsumi Yoriko , Oguro Satoshi , Noguchi Hiroshi
Published: March 2004

A cDNA encoding a novel plant type III polyketide synthase (PKS) was cloned from rhubarb (Rheum palmatum). A recombinant enzyme expressed in Escherichia coli accepted acetyl‐CoA as a starter, carried out six successive condensations with malonyl‐CoA and subsequent cyclization to yield an aromatic heptaketide, aloesone. The enzyme shares 60% amino acid sequence identity with chalcone synthases (CHSs), and maintains almost identical CoA binding site and catalytic residues conserved in the CHS superfamily enzymes. Further, homology modeling predicted that the 43‐kDa protein has the same overall fold as CHS. This provides new insights into the catalytic functions of type III PKSs, and suggests further involvement in the biosynthesis of plant polyketides.
WOMEN, WORK, AND POLITICS IN MODERN EUROPE A history of European women's work: 1700 to the present. By Deborah Simonton. London: Routledge, 1998. Pp. 337. ISBN 0-415-05532-6. £17.99. France and women, 1789–1914: gender, society and politics. By James McMillan. London: Routledge, 2000. Pp. 286. ISBN 0-415-22603-1. £19.99. The rise of professional women in France: gender and public administration since 1830. By Linda Clark. Cambridge: Cambridge University Press, 2000. Pp. 324. ISBN 0-521-77344-X. £45.00.
Authors: DE BELLAIGUE CHRISTINA
Published: March 2004

In 1848 one of the first female inspectors appointed by the French state argued that ‘the inspection of nursery schools can be done usefully and correctly only by women … Inspectresses will intimidate less and will persuade more readily than men can.’ Her statement points to the ambiguous position of many working women in the nineteenth century. Working outside what was perceived as a feminine domestic sphere, their employment was justified with reference to a domestic ideal of femininity. Though each has a different focus, the three books reviewed here all demonstrate how ideas about the nature of women served both to extend and to limit women's opportunities in nineteenth- and twentieth-century France and Europe.
MONASTIC POVERTY AND MATERIAL CULTURE IN EARLY MODERN ITALIAN CONVENTS
Authors: EVANGELISTI SILVIA
Published: March 2004

This article discusses the meaning of material culture in early modern Italian convents. Although nuns were required to give up private property rights and embrace religious poverty, many of them brought into the convent a vast range of material objects and goods for their personal use. These goods could also be given away, exchanged, or lent to others within the monastic community and even outside it. By exploring the circulation of objects, money, and goods, we get an interesting picture of how female monastic institutions worked internally and interacted with the city. We also gain a better understanding of the role of objects in articulating religious discipline and regulating the networks of interpersonal relations within cloistered communities.
THE RISE OF THE COFFEEHOUSE RECONSIDERED
Authors: COWAN BRIAN
Published: March 2004

This article offers a history of British seventeenth-century coffeehouse licensing which integrates an understanding of the micro-politics of coffeehouse regulation at the local level with an analysis of the high political debates about coffeehouses at the national level. The first section details the norms and practices of coffeehouse licensing and regulation by local magistrates at the county, city, and parish levels of government. The second section provides a detailed narrative of attempts by agents of the Restoration monarchy to regulate or indeed suppress the coffeehouses at the national level. The political survival of the new institution is attributed to the ways in which public house licensing both regulated and also legitimated the coffeehouse. The rise of the coffeehouse should not be understood as a simple triumph of a modern public sphere over absolutist state authority; it offers instead an example of the ways in which the early modern norms and practices of licensed privilege could frustrate the policy goals of the Restored monarchy.
LOCKE IN FRENCH: THE DU GOUVERNEMENT CIVIL OF 1691 AND ITS READERS
Authors: SAVONIUS S.-J.
Published: March 2004

The recent advances in Locke scholarship have given us a vivid description of the context in which Locke drafted the Two treatises of government. Yet, inadvertently, the result has been a skewed perspective on his concerns. As the focus has been on the English crisis in 1679–83 as the specific context from which Locke's theories emanated, the contexts in which they were published have attracted less attention. Redressing the balance, this article brings out Locke's participation in Francophone discussion in the context of a European crisis. After the Revolution of 1688–9 Locke's ‘Second treatise’ was translated into French by David Mazel, a Huguenot cleric. The article shows that Mazel's translation, the Du gouvernement civil, provided the Francophone readership with an anti-absolutist critique of the French regime, and that it emanated from the circle of Locke's closest friends. It was through the intermediary of a handful of Francophone Protestants that the Continental audience became aware of Locke's arguments and that he became known, not only as a theoretical philosopher, but also as a political theorist – as the author of, not the Two treatises, but the Du gouvernement.
THE IMPERIAL SIGNIFICANCE OF THE CANADIAN–AMERICAN RECIPROCITY PROPOSALS OF 1911
Authors: POTTER SIMON J.
Published: March 2004

This article builds on the recent willingness among British, Canadian, and imperial historians to question older national histories, and to re-examine how the divergent societies, economies, and polities of the empire once interacted in a wider ‘British world’. It argues that the press acted as a key mechanism for the transmission of political ideas through the permeable internal boundaries of empire. This is demonstrated through analysis of contemporary debate over the Canadian–American reciprocity proposals of 1911. This controversy provided an opportunity for political groups in Britain and Canada to use the press to forge alliances with each other and work together on a specific issue. Two key forces made this possible. In Britain, constructive imperialists had since 1903 sought to rally Dominion support for tariff reform, initially with limited success. In Canada, neither western farmers nor eastern manufacturers seemed interested in imperial preference. It was the reciprocity proposals that changed the situation, providing the second driving force. Canadian manufacturing interests, seeking to prevent the lowering of tariff barriers against United States rivals, began to court British constructive imperialists. As a result political conflict was reshaped both in colony and metropole.
THE SUPERWOMAN: THEORIES OF GENDER AND GENIUS IN EDWARDIAN BRITAIN
Authors: DELAP LUCY
Published: March 2004

This article examines the development of the idea of the ‘superwoman’ among British Edwardian feminists and contextualizes it within the aristocratic political thought of the day. I examine the idea of the ‘genius’ and the ‘superman’ in order to shed light on why, for some Edwardian feminists, the ideal feminist agent was to be an elite, discerning, remote figure. I argue that Edwardian feminism witnessed an ‘introspective turn’, marked by an interest in character, will, and personality as the key components of emancipation. The focus of political change was firmly located within women themselves. This belief was widespread, even though only a minority chose the language of the ‘superwoman’ to elaborate it. References to the ‘superwoman’ indicates the impact of Nietzschean and egoist ideas upon the women's movement. The ‘superwoman’ was used to position feminism as a movement not just for political rights but for wider social regeneration, and represents a characteristically Edwardian belief in the power of the ‘exceptional individual’ to promote social change.
BALDWIN'S REPUTATION: POLITICS AND HISTORY, 1937–1967
Authors: WILLIAMSON PHILIP
Published: March 2004

In one fundamental sense, a British post-war consensus certainly existed: repudiation and denigration of interwar governments and their leaders. Stanley Baldwin was the chief victim, as it became widely believed during the 1940s that he had ‘failed to rearm’ the nation in the 1930s. Examination of the history of Baldwin's reputation after his retirement – precisely why and how it collapsed – reveals a striking case of the contingent construction of historical interpretation. Partisan politics, legitimation of a new regime, a Churchillian bandwagon, self-exoneration, and selective recollection together reinforced hindsight and a wartime appetite for scapegoats to create a public myth, which despite manifest evidence to the contrary was accepted as historical ‘truth’ by historians and other intellectuals. The main indictment was accepted even by Baldwin's appointed biographer, who added a further layer of supposed psychological deficiencies. Attempts to establish an effective defence were long constrained by official secrecy and the force of Churchill's post-war prestige. Only during the 1960s did political distance and then the opening of government records lead to more balanced historical assessments; yet the myth had become so central to larger myths about the 1930s and 1940s that it persists in general belief.
‘CLEAN’ AND ‘DIRTY’: CATTLE DISEASE AND CONTROL POLICY IN COLONIAL KENYA, 1900–40
Authors: WALLER RICHARD
Published: March 2004

This article traces and contextualizes the development of veterinary policy in Kenya from 1900 to 1940, with particular reference to three diseases: East Coast Fever, bovine pleuro-pneumonia and rinderpest. Disease affected almost every aspect of society and economy in Kenya, but the threat that it posed was constructed and confronted differently by the various constituencies – official, settler and African – that made up the divided pastoral economy. Policy emerged and changed from containment to eradication as the result of continuous argument, in which the Colonial Office played a key role, about both the nature of disease and the most effective way of combating it.
THE HISTORIAN WHO WOULD BE CHIEF: A BIOGRAPHY OF SIMON JILUNDU CHIBANZA III, 1899–1974
Authors: MACOLA GIACOMO
Published: March 2004

By recovering from obscurity the life story of an early Zambian historian, this paper makes a case for the adoption of a biographical approach to the study of Africa's colonial history. It argues that Simon Jilundu Chibanza III's trajectory provides valuable insights into the ambivalent social location and intricate motivations of the Zambian intelligentsia during colonial rule. An examination of his background and variegated career accounts for the complexity of his identity and the imprints which its multiple strands left upon his literary output and profound understanding of the politics of history-writing.
THE ENVIRONMENTAL CONSEQUENCES OF INDEPENDENCE AND SOCIALISM IN NORTH PARE, TANZANIA, 1961–88
Authors: SHERIDAN MICHAEL J.
Published: March 2004

This article draws on archival sources and oral histories to describe changing post-colonial land management in the North Pare Mountains of Tanzania. The independent state transformed colonial institutions but did not maintain colonial common property regimes for water source, irrigation and forest management. Farmers responded by encroaching upon and dividing the commons. After 1967, Tanzania's socialist policies affected environmental conditions in North Pare indirectly by increasing the ambiguity and negotiability of resource entitlements. The material, social and cultural legacies of these processes include environmental change, declining management capacity and persistent doubt about the value of ‘conservation’.
TRADERS, ‘BIG MEN’ AND PROPHETS: POLITICAL CONTINUITY AND CRISIS IN THE MAJI MAJI REBELLION IN SOUTHEAST TANZANIA
Authors: BECKER FELICITAS
Published: March 2004

This article places the origins of the Maji Maji rebellion in Southeast Tanzania within the context of tensions between coast and interior, and between ‘big man’ leaders and their followers, which grew out of the expansion of trade and warfare in the second half of the nineteenth century. Without discounting its importance as a reaction against colonial rule, the paper argues that the rebellion was driven also by the ambitions of local leaders and by opposition to the expansion of indigenous coastal elites. The crucial role of the ‘Maji’ medicine as a means of mobilization indicates the vitality of local politics among the ‘stateless’ people of Southeast Tanzania.
THE STATE, CHIEFS AND THE CONTROL OF FEMALE MIGRATION IN COLONIAL SWAZILAND, c. 1930s–1950s
Authors: SIMELANE HAMILTON SIPHO
Published: March 2004

Human migration has played an important role in the construction or dissolution of states in southern Africa. With the coming of the colonial period there was an intensification of the process of migration, mainly for work. Such movements were premised on the uneven development of colonial economies in which some areas became suppliers of labour while others became labour markets. In the case of Swaziland, the migration of labour was dominated by male migrants as the existing labour markets offered more opportunities for men. This view has become a conventional interpretation of the disparity in the mobility of men and women within states or across borders. This article uses the experience of Swaziland to extend the discourse on why men dominated the migration currents in Swaziland during the colonial period. It points out that it is no longer useful to rely on purely economic explanations of why more men were migrating than women in colonial Swaziland. The argument pushes the frontier of analysis beyond economics and argues that a more significant explanation is to be found in the power relations at the homestead level, whereby men had the power to determine if and when women could migrate. The discussion shows that Swazi men, in collaboration with colonial administrators, employed different strategies to control the mobility of women. The intention of the men was to keep women in the rural areas and they used their power in the homestead and their influence on the colonial administration to create barriers against female migration to local and cross-border industrial centres.
Fate of ivermectin residues in ewes' milk and derived products
Authors: Cerkvenik Vesna , Perko Bogdan , Rogelj Irena , Doganoc Darinka Z , Skubic Valentin , Beek Wim MJ , Keukens Henk J
Published: March 2004

The fate of ivermectin (IVM) residues was studied throughout the processing of daily bulk milk from 30 ewes (taken up to 33 d following subcutaneous administration of 0·2 mg IVM/kg b.w.) in the following milk products: yoghurt made from raw and pasteurized milk; cheese after pressing; 30- and 60-day ripened cheese; and whey, secondary whey and whey proteins obtained after cheese–making (albumin cheese). The concentration of the H2B1a component of IVM was analysed in these dairy products using an HPLC method with fluorescence detection. The mean recovery of the method was, depending on the matrix, between 87 and 100%. Limits of detection in the order of only 0·1 μg H2B1a/kg of product were achieved. Maximum concentrations of IVM were detected mostly at 2 d after drug administration to the ewes. The highest concentration of IVM was found on day 2 in 60-day ripened cheese (96 μg H2B1a/kg cheese). Secondary whey was the matrix with the lowest concentration of IVM (<0·6 μg H2B1a/kg). Residue levels fell below the limits of detection between day 5 (for secondary whey) and day 25 (for all cheese samples). In the matrices investigated, linear correlations between daily concentrations of IVM, milk fat and solid content were evident. During yoghurt production, fermentation and thermal stability of IVM was observed. During cheese production, approximately 35% of the IVM, present in the raw (bulk) milk samples, was lost. From the results it was concluded that the processing of ewes' milk did not eliminate the drug residues under investigation. The consequences of IVM in the human diet were discussed. Milk from treated animals should be excluded from production of fat products like cheese for longer after treatment with IVM than for lower fat products.
High pressure treatment of bovine milk: effects on casein micelles and whey proteins
Authors: Huppertz Thom , Fox Patrick F , Kelly Alan L
Published: March 2004

Effects of high pressure (HP) on average casein micelle size and denaturation of α-lactalbumin (α-la) and β-lactoglobulin (β-lg) in raw skim bovine milk were studied over a range of conditions. Micelle size was not influenced by treatment at pressures <200 MPa, but treatment at 250 MPa increased micelle size by ∼25%, while treatment at [ges ]300 MPa irreversibly reduced it to ∼50% of that in untreated milk. The increase in micelle size after treatment at 250 MPa was greater with increasing treatment time and temperature and milk pH. Treatment times [ges ]2 min at 400 MPa resulted in similar levels of micelle disruption, but increasing milk pH to 7·0 partially stabilised micelles against HP-induced disruption. Denaturation of α-la did not occur [les ]400 MPa, whereas β-lg was denatured at pressures >100 MPa. Denaturation of α-la and β-lg increased with increasing pressure, treatment time and temperature and milk pH. The majority of denatured β-lg was apparently associated with casein micelles. These effects of HP on casein micelles and whey proteins in milk may have significant implications for properties of products made from HP-treated milk.
Induction of stress tolerance in Lactobacillus delbrueckii ssp. bulgaricus by the addition of sucrose to the growth medium
Authors: Silva Joana , Carvalho Ana Sofia , Pereira Helena , Teixeira Paula , Gibbs Paul A
Published: March 2004

The lactic acid bacteria (LAB) play an important role in the production of fermented foods. The development of concentrated cultures of LAB, for inoculating the production vat directly (bulk starters), has eliminated many problems traditionally involved in their preparation and maintenance by the food industry. For industrial use, LAB are often preserved in a frozen or dried form, the latter preparations having lower transport and storage costs (Kets et al. 1996). Dried cultures, however, lose viability/activity during storage, especially when kept at room temperature (Champagne et al. 1991; Teixeira et al. 1995a,b; Castro et al. 1996). Attempts to improve the survival of LAB during drying have already been tried (Linders et al. 1997b; Gardiner et al. 2000). Previous results indicated a direct relationship between the presence of compatible solutes in LAB and their ability to survive drying conditions. Such solutes include amino acids, amino acid derivatives, quaternary amines, sugars and tetrahydropyrimidines (Kets & De Bont, 1994; Kets et al. 1994, 1996).
Dietary fat regulates mammary stearoyl CoA desaturase expression and activity in lactating mice
Authors: Singh Kuljeet , Hartley Darren G , McFadden Thomas B , Mackenzie Duncan DS
Published: March 2004

Mice in mid lactation (n=6 per group) were fed a control diet (1·19% fat), or diets containing safflower oil (25% w/w) or olive oil (25% w/w) for 7 d. Mammary and liver stearoyl CoA desaturase (SCD) mRNA levels and mammary SCD activities were higher in lactating mice fed the control diet than in those fed the oil-supplemented diets. Further, mammary SCD mRNA was directly related to mammary SCD activity. Milk fat composition was influenced by dietary fat composition. The olive oil diet, high in 18[ratio ]1, led to high levels of this fatty acid in milk and the safflower oil diet, high in 18[ratio ]2, resulted in a milk fat with high levels of 18[ratio ]2. These results show that there is regulation of SCD at the transcriptional level, associated with changes in enzyme activity and in milk fat composition.
Goats' milk xanthine oxidoreductase is grossly deficient in molybdenum
Authors: Atmani Djebbar , Benboubetra Mustapha , Harrison Roger
Published: March 2004

Xanthine oxidoreductase (XOR) was purified from goats' milk. The u.v.–visible absorption spectrum was essentially identical to those of the corresponding bovine and human milk enzymes and showed an A280/A450 ratio of 5·20±0·12, indicating a high degree of purity. Like bovine and human milk XORs, enzyme purified from goats' milk showed a single band on SDS-PAGE corresponding to a subunit with approximate Mr 150000. On Western blotting, mouse monoclonal anti-human XOR antibody cross-reacted with purified caprine and bovine XORs. The specific xanthine oxidase activity of goats' milk XOR, however, was very much lower than that of bovine XOR, although NADH oxidase activities of XOR from the two sources were similar. In these respects, the caprine milk XOR mirrors the human milk enzyme, in which case the kinetic effects have previously been attributed to relatively low molybdenum content. The molybdenum content of goats' milk XOR also was shown to be relatively low, with 0·09 atoms Mo per subunit, compared with 0·55 atoms Mo per subunit for the bovine enzyme. A parallel purification of human milk XOR showed 0·03 atoms Mo per subunit. The possible physiological significance of the low molybdenum content of the caprine milk enzyme and of its correspondingly low enzymic activity is discussed.
Effects of selective and complete dry therapy on prevalence of intramammary infection and on milk yield in the subsequent lactation in dairy ewes
Authors: Gonzalo Carlos , Tardáguila J Alfonso , De La Fuente L Fernando , San Primitivo Fermín
Published: March 2004

The study was carried out in a commercial flock on 286 Churra breed ewes (566 half-udders) assigned to three lots depending on the type of antibiotic dry therapy received in the lactation previous to the one studied. One-hundred-and-four ewes were given complete therapy in all udders, 103 received selective therapy of infected half-udders, and 79 received no therapy at all. Half-udders of all animals were sampled for bacteriological study at ≤72 h (lambing), 60 d, 120 d, and 155 d (drying-off) post partum. Dry therapy, parity number, lactation stage and therapy×parity interaction contributed significantly to variation in intramammary infection prevalence. Antibiotic dry therapy had the most significant effect. Prevalence during the whole of the subsequent lactation was significantly lower in lots receiving complete (18·8%) and selective (15·6%) dry therapy than in the untreated control lot (48·3%). Coagulase-negative staphylococci and streptococci (in particular Streptococcus agalactiae) were the organisms most significantly affected by dry therapy. In untreated ewes, prevalence increased noticeably from the 2nd to the 6th and subsequent lactations, but no significant changes were observed in the treated lots. Milk yield in the dry treated lots was 6·9% higher that in the untreated one. It was concluded that complete and selective treatments of ewes at drying-off were efficient and comparable methods of reducing the intramammary infection prevalence, improving bacteriological quality of milk, and increasing milk yield.
Functional expression of bcl-2 protein family and AIF in bovine mammary tissue in early lactation
Authors: Colitti Monica , Wilde Colin J , Stefanon Bruno
Published: March 2004

Cell proliferation and apoptosis were measured in bovine mammary tissue around the time of peak milk production in three heifers, and compared with changes in the expression of bcl-2-related intracellular signals and apoptosis-inducing factor (AIF). Cell proliferation and apoptosis were relatively constant during the study period with no significant change in the incidence of either event. However, the ratio of apoptotic to proliferating cells tended to change from 0·99 on day 45 of lactation to 1·82 on day 63 (P=0·064), suggesting that in the course of the study, a dynamic balance may have been succeeded by net cell loss. Average milk production recorded 6 d after biopsy was correlated with the estimated number of cells (r=0·898; P<0·01) but not with the apoptosis to proliferation ratio (r=−0·224, P>0·05). Turnover of the cell population was associated with relatively constant expression of anti-apoptotic bcl-2. Competitive PCR also indicated expression of bax, in contrast to observations in lactating rodent mammary tissue. Bax expression was relatively low compared with that of bcl-2, but immunohistochemical staining for bax protein, which was not detectable on day 45, was observed on day 53 and, more intensely, on day 60 when the protein appeared to be membrane-associated. A partial coding sequence for bovine AIF was identified and AIF expression was evaluated by in situ hybridization. The results indicated that AIF was expressed in luminal alveolar cells and that, in concert with a change in bax to bcl-2 ratio, they might contribute to signalling of a change in the dynamic balance of the cell population as lactation progresses.
Oxidative stability of buttermilk as influenced by the fatty acid composition of cows' milk manipulated by diet
Authors: Kristensen Dorthe , Hedegaard Rikke V , Nielsen Jacob H , Skibsted Leif H
Published: March 2004

Milk from cows fed a low-fat diet high in cereals designed to stimulate fat synthesis de novo was lower in unsaturated fatty acids (21·3%) than milk from cows fed a diet high in fat, mainly from roasted soy beans (41·3% unsaturated fatty acids). Buttermilk from the more unsaturated milk was less oxidatively stable during storage (at 4 °C, followed for 11 d) than buttermilk from the more saturated milk, as monitored both by primary lipid oxidation products (lipid hydroperoxides) and by the secondary lipid oxidation product, hexanal. Fat-soluble antioxidants, β-carotene and α-tocopherol, analysed by HPLC, were not consumed during storage for either of the two types of buttermilk. In contrast, the antioxidative capacity of the serum phase decreased during storage as evaluated in a radical scavenging assay based on the semi-stable water-soluble radical nitrosodisulphonate (Fremy's salt). The time course for the decrease in water-soluble antioxidants was very similar for the two types of buttermilk suggesting that oxidation is initiated in the serum phase independently of fatty acid composition.
Primary structure of water buffalo α-lactalbumin variants A and B
Authors: Chianese Lina , Caira Simonetta , Lilla Sergio , Pizzolongo Fabiana , Ferranti Pasquale , Pugliano Giovanni , Addeo Francesco
Published: March 2004

A novel electrophoretic α-lactalbumin (α-la) variant was detected in the Italian water buffalo breed. The isoelectric point of the variant, labelled A, was lower than the most frequent variant B. It presented an allelic frequency of 0·5% compared with the 97·1% of the BB allele. From Liquid Chromatography-Electrospray Ionization/Mass spectrometry, the molecular mass of the two α-la A and B variants were measured as 14235·1±0·8 and 14236·1±0·9 Da, respectively. The two proteins were sequenced and differentiated from one another by a single amino acid substitution, Asn45(B)→Asp45(A). As this amino acid substitution altered the N-glycosylation sequence consensus Asn45–X–Ser46 it may be deduced that the protein glycosylation level of the α-la A would decrease.
Effects of including silage in the diet on volatile compound profiles in Montasio cheese and their modification during ripening
Authors: Stefanon Bruno , Procida Giuseppe
Published: March 2004

Effects of including silage in the diet on volatile compound profiles and their modification during ripening of Montasio cheeses were examined. Twelve farms were selected and grouped according the type of forage in the ration: hay-based diets (four farms); hay and corn silage-based diets (four farms); and diets based on hay, corn silage and grass silages (four farms). For cheesemaking, 1000 kg of milk collected from two consecutive milkings was sampled from each farm and processed in the same cheese factory. Cheeses were ripened in the same cellar, in controlled humidity (78–85% relative humidity) and temperature (9–12°C), until analysis. After 68 (62–74), 200 (194–206) and 360 (354–366) d of ripening, a cheese from each batch was analysed for moisture, protein and fat, volatile fatty acids (VFA) and volatile compounds. These latter were analysed by dynamic reverse carrier gas headspace gas chromatographic mass spectrometry (GC-MS) technique, scanning from m/z 29 to m/z 300 at 0·5 s cycle time. Total and individual VFA contents of cheeses did not differ between the different dietary treatments and increased linearly (P<0·01) during ripening, indicating that there were no appreciable defects of fermentation. Sixty-two volatile compounds were identified in the cheese samples: 12 aldehydes, 9 ketones, 16 alcohols, 17 esters, 2 hydrocarbons, 4 sulphur-containing compounds and 2 terpenes. Diet significantly affected the amount of total alcohols, ethanol, isobutanol, 1-penten-3-ol, 2-methyl-1-butanol and the sum of all the volatile compounds. Significant variations of 33 volatile compounds (9 aldehydes, 4 ketones, 6 alcohols, 10 esters, 1 hydrocarbons, 2 sulphur containing compounds, and 1 terpene) were observed during ripening. These results suggest that the influence of diet composition on volatile compounds of matured cheeses are related more to effects on microbial and chemical fermentations in cheese during ripening rather than to a direct transfer of molecules from milk.
A comparison of the composition, coagulation characteristics and cheesemaking capacity of milk from Friesian and Jersey dairy cows
Authors: Auldist Martin J , Johnston Keith A , White Nicola J , Fitzsimons W Paul , Boland Michael J
Published: March 2004

Twenty-nine multiparous cows of each of the Jersey and Friesian breeds, all κ-casein AB phenotype, were grazed together and managed identically. On three occasions during 10 d in spring (early lactation), milk was collected from all cows at four consecutive milkings and bulked according to breed. On a separate occasion, milk samples were also collected from each cow at consecutive a.m. and p.m. milkings to form one daily sample per cow. The bulked milks (800–1000 l per breed on each occasion) were standardized to a protein[ratio ]fat (P[ratio ]F) ratio of 0·80, and 350 l from each breed was made into Cheddar cheese. The solids content of the remaining Friesian milk was then increased by ultrafiltration to a solids concentration equal to that of the Jersey milk. This solids-standardized Friesian milk and a replicate batch of P[ratio ]F standardized Jersey milk were made into two further batches of Cheddar cheese in 350-l vats. Compared with Friesian milk, Jersey milk had higher concentrations of most milk components measured, including protein, casein and fat. There were few difference in milk protein composition between breeds, but there were differences in fat composition. Friesian milk fat had more conjugated linoleic acid (CLA) than Jersey milk fat. Jersey milk coagulated faster and formed firmer curd than Friesian milk. Concentrations of some milk components were correlated with coagulation parameters, but relationships did not allow prediction of cheesemaking potential. Jersey milk yielded 10% more cheese per kg than Friesian milk using P[ratio ]F standardized milk, but for milks with the same solids concentration there were no differences in cheese yield. No differences in cheese composition between breeds were detected. Differences in cheesemaking properties of milk from Jerseys and Friesians were entirely related to the concentrations of solids in the original milk.
Texture, proteolysis and viable lactic acid bacteria in commercial Cheddar cheeses treated with high pressure
Authors: Wick Cheryl , Nienaber Uwe , Anggraeni Olga , Shellhammer Thomas H , Courtney Polly D
Published: March 2004

High pressure processing was investigated for controlling Cheddar cheese ripening. One-month- or 4-month-old Cheddar cheeses were subjected to pressures ranging from 200 to 800 MPa for 5 min at 25 °C. The number of viable Lactococcus lactis (starter) and Lactobacillus (nonstarter) cells decreased as pressure increased. Subsequent storage of the control and pressure-treated cheeses at 10 °C caused viable cell counts to change in some cases. Free amino acid content was monitored as an indicator of proteolysis. Cheeses treated with pressures [ges ]400 MPa evolved free amino acids at significantly lower rates than the control. No acceleration in free amino acid development was observed at lower pressures. Pressure treatment did not accelerate the rate of textural breakdown compared with the non-pressure treated control. On the contrary, pressure treatment at 800 MPa reduced the time-dependent texture changes. Results indicate that high pressure may be useful in arresting Cheddar cheese ripening.
Casein proteolysis in human milk: tracing the pattern of casein breakdown and the formation of potential bioactive peptides
Authors: Ferranti Pasquale , Traisci Maria Vittoria , Picariello Gianluca , Nasi Antonella , Boschi Velia , Siervo Mario , Falconi Claudio , Chianese Lina , Addeo Francesco
Published: March 2004

The protein and peptide fraction of human milk samples collected from mothers of pre- and full-term infants in the first week after parturition was analysed by use of liquid chromatography-mass spectrometry and tandem mass spectrometry. By characterising the peptide sequence, we defined the pathway of casein hydrolysis which leads to the formation of small peptides through intermediate oligopeptides. It was found that the action of a plasmin-like enzyme acting on specific lysine residues is the primary step in casein degradation. This is followed by endopeptidases and/or exopeptidases mediated cleavage of the oligopeptides which, in turn, produces a multiplicity of short peptides differing by one or more amino acid residues. In this process, a series of potentially bioactive peptides (opioid, phosphopeptides) and their precursors are produced.
Microstructure and rheology of an acid-coagulated cheese (Karish) made with an exopolysaccharide-producing Streptococcus thermophilus strain and its exopolysaccharide non-producing genetic variant
Authors: Hassan Ashraf N , Corredig Milena , Frank Joseph F , Elsoda Morsi
Published: March 2004

The objective of this research was to determine the effect of exopolysaccharide (EPS) production by lactic acid bacteria on the microstructure and rheology of Karish cheese, a soft acid coagulated cheese made using skim milk. An EPS-producing strain of Streptococcus thermophilus, and its EPS non-producing genetic variant were used to make comparable batches of the cheese. EPS in cheese was visualized by cryo-SEM as a large, dense, filamentous mass. Cheese made with the EPS non-producing culture was characterized by a dense protein network with smaller pores compared to that prepared with the EPS-producing culture. High elastic and viscous moduli measured by dynamic rheology were observed for EPS negative cheese and was attributed to its dense protein network. Creep test experiments demonstrated that cheese prepared with the EPS non-producing strain was more rigid and recovered its deformation, while cheese made using the EPS producing culture was more deformable. These results indicate that EPS-producing cultures can improve the physical properties of Karish cheese by reducing undesirable rigidity.
Protease-induced aggregation of bovine α-lactalbumin: Identification of the primary associating fragment
Authors: Otte Jeanette , Ipsen Richard , Ladefoged Anne Marie , Sørensen John
Published: March 2004

Details in the hydrolysis of α-lactalbumin known to result in formation of highly ordered nanotubules, was investigated by incubation of solutions with 10 g α-lactalbumin/l with a specific protease from Bacillus licheniformis (BLP). After 50 min of incubation, soluble aggregates were formed, the concentration of which increased until precipitation occurred after 200 min. The latter aggregates were dissolved in urea or at low pH, like the nanotubules characteristic of gels formed by the action of BLP on α-lactalbumin at 100 g/l. On the molecular level, α-lactalbumin was initially cleaved into two large hydrophobic fragments with masses of 11·6 and 11·3 kDa, which in turn were cleaved in a stepwise manner into the ultimate fragment of 8·8 kDa. This fragment was the predominating component in the insoluble aggregates, and was identified as the sequences 26–37 and 50–113 of α-lactalbumin linked together by a disulphide bond. Cleavage of α-lactalbumin into this fragment probably created new hydrophobic surfaces and new calcium binding sites allowing its association into ordered structures.