Campylobacter jejuni is a foodborne bacterial pathogen that is common in the developed world. However, we know less about its biology and pathogenicity than we do about other less prevalent ...pathogens. Interest in C. jejuni has increased in recent years as a result of the growing appreciation of its importance as a pathogen and the availability of new model systems and genetic and genomic technologies. C. jejuni establishes persistent, benign infections in chickens and is rapidly cleared by many strains of laboratory mouse, but causes significant inflammation and enteritis in humans. Comparing the different host responses to C. jejuni colonization should increase our understanding of this organism.
Normal fibroblasts cultured as monolayers secrete matrix metalloproteinases (MMP), including gelatinase A (72-kDa type IV collagenase) as inactive zymogens. Previously we found that normal ...fibroblasts cultured in a type I collagen lattice (dermal equivalent) secrete active gelatinase A. Here we show that the activation of progelatinase A occurs within the cell and that the activator copurifies with Golgi membranes. Cell extracts of fibroblasts cultured in collagen lattices contain active 62-kDa gelatinase A at least 4-6 h before active enzyme is detected in the culture medium. Pulse--chase experiments confirm these results. The activator is membrane-bound and localizes to the Golgi-enriched fraction. Highly purified plasma membranes from lattice cultures are unable to convert gelatinase A from the zymogen to its active form. The activator may be a metalloproteinase because EDTA prevents activation of exogenous proenzyme by membrane fractions. Membrane-type MMP1, the enzyme thought to be responsible for activation of gelatinase A on the plasma membrane of tumor cells, shows no significant change in either mRNA or protein levels during lattice culture. Intracellular levels of gelatinase A mRNA and protein increase during the culture period, and tissue inhibitor of metalloproteinases concentration does not change. Because of the greater availability of tissue inhibitor of metalloproteinases-free proenzyme as a substrate for the activator, it is possible that membrane-type MMP1 is the activating enzyme. In that case, malignant transformation may involve a change in the localization of the activator to the plasma membrane.
From the characterization of enzyme activities and the analysis of genomic sequences, the complement of DNA methyltransferases (MTases) possessed by the cyanobacterium ANABAENA PCC 7120 has been ...deduced. ANABAENA has nine DNA MTases. Four are associated with Type II restriction enzymes (AVAI, AVAII, AVAIII and the newly recognized inactive AVAIV), and five are not. Of the latter, four may be classified as solitary MTases, those whose function lies outside of a restriction/modification system. The group is defined here based on biochemical and genetic characteristics. The four solitary MTases, DmtA/M.AVAVI, DmtB/M.AVAVII, DmtC/M. AVAVIII and DmtD/M.AVAIX, methylate at GATC, GGCC, CGATCG and rCCGGy, respectively. DmtB methylates cytosines at the N4 position, but its sequence is more similar to N6-adenine MTases than to cytosine-specific enzymes, indicating that it may have evolved from the former. The solitary MTases, appear to be of ancient origin within cyanobacteria, while the restriction MTases appear to have arrived by recent horizontal transfer as did five now inactive Type I restriction systems. One Mtase, M.AVAV, cannot reliably be classified as either a solitary or restriction MTase. It is structurally unusual and along with a few proteins of prokaryotic and eukaryotic origin defines a structural class of MTases distinct from all previously described.
The efforts of the child development movement to understand development and the factors influencing it have been the basis of 2 interrelated tasks: the scientific study of children, and the ...dissemination of this knowledge to parents. Content analysis is used to assess the extent to which psychological theories and research about infants have been communicated to parents from 1955 to 1984 in 2 popular publications, the Infant Care manual and Parents magazine. Results indicated that there is not a singular relation between what experts know and what is communicated to parents. Information reflecting scientific advances about the biological components of infant development (perception, cognition, and temperament) have been most accurately communicated to parents, whereas discussions of the mother-infant relationship, child care, feeding, and fathers appeared to be related to the broader cultural context and demographic changes over the past thirty years. This study reveals an interaction between science and culture in our theories of infant development and child rearing.
Reports an error in "Maternal emotional reactions to the premature infant in the context of the family" by Robert M. Hodapp and Kathryn T. Young ( Canadian Journal of Behavioural Science Revue ...canadienne des Sciences du comportement, 1992Jan, Vol 241, 29-40). The authors of the article should be listed as Robert M. Hodapp, Yale University, Kathryn T. Young, Yale University, Marie Algieri, Hospital for Sick Children, and Klaus Minde, Montreal Children's Hospital. The two last names were inadvertendly omitted. (The following abstract of the original article appeared in record 1992-27071-001.) Examined maternal emotional reactions to the birth and early development of premature infants and whether such reactions are influenced by specific social support variables. 22 mothers of premature infants (aged 26–31 wks) were rated on 13 general psychological characteristics common to "maternal mourning reactions" of mothers of handicapped and at-risk children. Ss experienced relatively brief adverse reactions. The proposed 3-stage model of maternal mourning (i.e., shock; emotional disorganization; emotional organization) did not appear to characterize this sample. Ss with supportive spouses and close friends experienced less severe emotional reactions, as did Ss whose husbands were looking forward to becoming fathers. (French abstract) (PsycINFO Database Record (c) 2016 APA, all rights reserved) (Source: journal abstract)
This study examined maternal emotional reactions to the birth and early development of premature infants and whether such reactions are influenced by specific social support variables. Extensive ...clinical notes on 22 mothers were coded at 7 points throughout the first 14 months of the premature infant's life. Mothers were rated on 13 general psychological characteristics common to "maternal mourning reactions" of mothers of handicapped and at-risk children. Mothers of premature infants experienced shorter adverse reactions than previously reported for mothers of other types of disabled children; in addition, the proposed three-stage model of maternal mourning (i.e., shock; emotional disorganization; emotional organization) did not appear to characterize this sample. Mothers with supportive spouses and close friends experienced less severe emotional reactions, as did mothers whose husbands were looking forward to becoming fathers. The clinical implications of these findings are discussed.
INFANT AND TODDLER DAY CARE Young, Kathryn T; Zigler, Edward
American journal of orthopsychiatry,
01/1986, Letnik:
56, Številka:
1
Journal Article
Recenzirano
Recent research indicates that there are identifiable and important characteristics of the day care environment that influence its quality and, ultimately, the psychological development of infants ...and toddlers. An analysis of existing licensing requirements reveals great variation among the 50 states in standards for infant and toddler day care. This absence of a uniform standard translates into a wide range of questionable experience for these very young children.
The efforts of the child development movement to understand development and the factors influencing it have been the basis of 2 interrelated tasks: the scientific study of children, and the ...dissemination of this knowledge to parents. Content analysis is used to assess the extent to which psychological theories and research about infants have been communicated to parents from 1955 to 1984 in 2 popular publications, the Infant Care manual and Parents magazine. Results indicated that there is not a singular relation between what experts know and what is communicated to parents. Information reflecting scientific advances about the biological components of infant development (perception, cognition, and temperament) have been most accurately communicated to parents, whereas discussions of the mother‐infant relationship, child care, feeding, and fathers appeared to be related to the broader cultural context and demographic changes over the past thirty years. This study reveals an interaction between science and culture in our theories of infant development and child rearing.
Energy taxis is the ability of microbes to alter their direction of motility in response to changes in their local environment that affect energy-generating processes. The energy taxis receptor Aer, ...in Escherichia coli, senses changes in the electron transport system via an FAD cofactor bound to a PAS domain. The PAS domain is thought to interact directly with another Aer domain, the HAMP domain, to transmit a signal to the conserved signaling domain found in chemotaxis receptors. This work focused on an energy taxis system in Campylobacter jejuni composed of two proteins, CetA and CetB, each sharing specific domains with Aer. CetB has a PAS domain; CetA has a predicted transmembrane region, HAMP domain and signaling domain. We examined the expression of cetA and cetB, as well as the biochemical properties of the proteins they encode. cetA and cetB are co-transcribed independently of the flagellar regulon. Both CetA and CetB localize to the membrane and participate in complexes, including a likely CetB dimer and a complex that may include both CetA and CetB. HAMP domains, found in many bacterial signal transduction proteins, generally transmit an intramolecular signal between an extracellular sensory domain and an intracellular signaling domain. Studies of HAMP domains in proteins where both the input and output signals occur intracellularly are limited to Aer. The CetA HAMP domain differs significantly from that of Aer in predicted secondary structure. Similarity searches identified 55 pairs of HAMP/PAS proteins encoded by adjacent genes in a diverse group of microorganisms. We propose that these HAMP/PAS pairs form a new family of bipartite energy taxis receptors. Additionally, CetA contributes to C. jejuni invasion of human epithelial cells, while CetB does not, suggesting that members of HAMP/PAS pairs may act independently of each other. This work provides a framework for future studies into the molecular mechanism of signal transduction within CetA and CetB. Further, these studies suggest that the CetA/CetB system may be a widespread alternative to Aer with additional functional flexibility arising from a capacity for each protein to act independently to regulate traits other than energy taxis.
The matrix metalloproteinase 72-kDa type IV collagenase (also known as gelatinase A) is thought to be involved in both normal connective tissue remodeling and invasive pathological processes. Like ...other matrix metalloproteinases, 72-kDa type IV collagenase is secreted by fibroblast monolayers as an inactive proenzyme, but is unique among this enzyme family in that it is not activated by serine proteinases such as plasmin. However, when fibroblasts are cultured in a collagen lattice, a situation thought to better approximate in vivo conditions, we have invariably found much of the secreted 72-kDa type IV collagenase in its enzymatically active 62-kDa form. Although collagen lattice contraction appeared to be required for the activation of 72-kDa type IV collagenase, we have found that the process of contraction can be dissociated from proenzyme activation. Both cytochalasin D and alpha-methylmannoside completely blocked lattice contraction, but not proenzyme activation. Furthermore, the monoclonal antibody M-13, which is directed against the beta 1 integrin chain, blocked collagen lattice contraction but not 72-kDa type IV procollagenase activation. At concentrations significantly higher than required to block lattice contraction or cell adhesion to collagen, M-13 was able to inhibit proenzyme activation. A second monoclonal antibody to the beta 1 integrin, P5D2, had little effect on collagen lattice contraction at low concentrations, but could significantly inhibit the activation of 72-kDa type IV procollagenase. Antibodies to the integrin alpha 2 chain also inhibited proenzyme activation. These data show that the activation of 72-kDa type IV collagenase proenzyme, like collagen lattice contraction, is mediated by beta 1 integrin receptors, possibly alpha 2 beta 1. Although both anti-beta 1 antibodies used are directed to the same site on the integrin chain, the fact that each antibody preferentially blocks a different event, either lattice contraction or activation of 72-kDa type IV collagenase, suggests the existence of branch points in the receptor-mediated signal transduction pathway.
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