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Biomedical subjects

D Jackson

Publications and source records attributed to D Jackson.

At least 91 records · Page 5Linked to original sources
PubMed1997

Mucosal addressin cell adhesion molecule-1 (MAdCAM-1). Its binding motif for alpha 4 beta 7 and role in experimental colitis.

The integrin alpha 4 beta 7 and mucosal addressin cell adhesion molecule-1 (MAdCAM-1) are molecules involved in the normal recirculation of lymphocytes between the blood and the gastrointestinal tract. These molecules may play a complementary and significant role in animal models of colitis. We have investigated the structural interaction between alpha 4 beta 7 and MAdCAM-1. Site-directed mutagenesis studies of the MAdCAM-1 molecule has led to the identification of the amino acid residue (LDT) in the loop between beta strands C and D of the Ig-superfamily-like folds being involved in the adhesive and cell activation functions of MAdCAM-1 with alpha 4 beta 7.

Amino Acid Sequence↗
PubMed1997

Retrograde cerebral perfusion provides limited distribution of blood to the brain: a study in pigs.

OBJECTIVE: The objective of this study was to investigate flow distribution during retrograde and antegrade cerebral perfusion with India ink as a marker. METHODS: Ten pigs received cerebral perfusion with a solution containing 50% filtered India ink for 5 minutes either antegradely through both internal carotid arteries at a flow of 180 to 200 ml/min (n = 5) or retrogradely via the superior vena cava at a flow of 300 to 500 ml/min (n = 5). The brains were then fixed for quantitative measurement of the density of ink-filled capillaries (reported as a percentage of the total selected area). The assessment was done with the use of an in-house software program. RESULTS: In the antegrade cerebral perfusion group, the intracranial arterial and venous systems were completely filled with ink. The gray matter was colored uniformly black, and light coloring was observed in the white matter. During retrograde cerebral perfusion, the majority of ink was returned to the inferior vena cava, and only a small amount of ink was found in the innominate artery draining from the brain. Massive ink filling was observed in the sagittal sinus and other venous sinuses in all the pigs. Vessels on the surface of the brain and large vessels in the brain were also well filled with ink. However, only 10% of capillaries were filled with ink during retrograde cerebral perfusion relative to the number observed with antegrade cerebral perfusion. CONCLUSIONS: Retrograde cerebral perfusion supplies a limited amount of blood to brain tissue, which flows mainly through superficial and large deep cerebral vessels.

Animals↗
PubMed1997

Morphogenesis on the move: cell-to-cell trafficking of plant regulatory proteins.

It has been shown recently that some plant transcription factors that regulate cell fate during development can traffic through plasmodesmata-the intercellular channels that connect plant cells. This phenomenon helps explain the non-autonomous effects of many developmental mutations in plants and defines a novel mechanism by which cells signal to each other during development.

Biological Transport↗
PubMed1997

A role for fibroblast growth factor signaling in the lobuloalveolar development of the mammary gland.

The inappropriate expression of growth factors, or activating mutations of their receptors, have been implicated as causative factors in mouse and human mammary cancer. For example, it has been known for some time that three members of the fibroblast growth factor (FGF) family behave like oncogenes in virally induced mammary cancer of mice. In normal circumstances, signaling via FGF receptors is known to mediate growth, differentiation, and patterning, during embryogenesis and fetal development. A powerful approach to dissecting the roles for these signaling pathways is to determine the developmental consequences of abrogating their function in transgenic mice. In this review, we describe the use of dominant negative FGF receptors to evaluate the contribution of specific FGF signals in normal mammary gland development. These studies have revealed that normal lobuloalveolar development requires FGF signaling to the mammary epithelium, a function that is presumably usurped by MMTV in mouse mammary tumorigenesis.

Animals↗
PubMed1997

Antibody to Haemophilus ducreyi among trucking company workers in Kenya.

BACKGROUND AND OBJECTIVES: To determine the prevalence, correlates, and incidence of Haemophilus ducreyi antibodies, a cohort of East African trucking company employees was evaluated. STUDY DESIGN: Human immunodeficiency virus (HIV)-1-seronegative men working in six trucking companies in Mombasa, Kenya, were evaluated with a questionnaire and serologic testing for antibodies to H. ducreyi and other sexually transmitted pathogens. Men who were initially H. ducreyi seronegative were retested at 1 year of follow-up. RESULTS: The H. ducreyi seroprevalence among 501 men at enrollment was 26.5%. Seropositivity was significantly associated with older age, married status, years of active sex life, number of sex partners in the past year, history of unprotected sex with a prostitute in the past year, and history of alcohol intake (all P values < 0.01). Occupational travel for more than 14 days per month was also significantly associated with H. ducreyi seropositivity (odds ratio [OR] 2.1, 95% confidence interval [CI] 1.3-3.2). Using multivariate analysis, H. ducreyi seropositivity was independently associated with age, married status, history of sex with a prostitute, and history of alcohol intake. Presence of H. ducreyi antibodies was significantly associated with seropositivity to the other major genital ulcerative pathogens, Treponema pallidum (OR 4.3, 95% CI 2.2-8.3), herpes simplex virus type 2 (OR 4.9, 95% CI 2.0-11.5), and Chlamydia trachomatis (OR 3.2, 95% CI 1.5-6.9). These associations remained significant after adjusting for demographic and exposure variables. The incidence of seroconversion to H. ducreyi antibodies was 3.6 per 100 person years. CONCLUSIONS: Serologic evidence of H. ducreyi infection was common among male trucking company employees. H. ducreyi seropositivity is an objective marker of high-risk behavior and is associated with serologic evidence of other ulcerative sexually transmitted diseases.

Adolescent↗
PubMed1997

In uncharted waters: confronting the culture of silence in a residential care institution.

This paper describes a study grounded in feminism, which explored the experiences of three registered nurses who were employed in a residential care institution in which they believed the standard of care to be unacceptably poor. Ultimately, the nurses became 'whistle blowers'. Data surrounding these events were gathered through serial encounters and analysed using feminist interpretive methods. Three distinct phases were revealed: (i) trepidation and optimizm; (ii) barriers and obstacles; and (iii) disillusionment and defeat. It was in this final phase that the whistle blowing occurred. For these women, whistle blowing was an intervention of last resort; a stressful and negative event that carried personal and professional cost. Issues pertaining to professional autonomy and patient advocacy are raised, together with concerns surrounding the appropriation by business people of the language and images of nursing, and the power of these people to negatively impact upon nursing practice.

Adult↗
PubMed1997

A randomized trial of group outpatient visits for chronically ill older HMO members: the Cooperative Health Care Clinic.

OBJECTIVE: To compare the impact of group outpatient visits to traditional "physician-patient dyad" care among older chronically ill HMO members on health services utilization and cost, self-reported health status, and patient and physician satisfaction. DESIGN: A 1-year randomized trial. SETTING: A group model HMO in the Denver Metropolitan area. PARTICIPANTS: Three hundred twenty-one members aged 65 and older, randomized to a group visit intervention (n = 160) or to usual care (n = 161). INTERVENTION: Patients with high health services utilization and one or more chronic conditions had monthly group visits with their primary care physician and nurse. Visits included health education, prevention measures, opportunities for socialization, mutual support, and for one-to-one consultations with their physician, where necessary. MEASUREMENTS: Health services utilization and associated cost, health status, and patient and physician satisfaction. RESULTS: Outcome measures obtained after a 1-year follow-up period showed that group participants had fewer emergency room visits (P = .009), visits to subspecialists (P = .028), and repeat hospital admissions per patient (P = .051). Group participants made more visits (P = .021) and calls (P = .038) to nurses than control group patients and fewer calls to physicians (P = .019). In addition, a greater percentage of group participants received influenza and pneumonia vaccinations (P < .001). Group participants had greater overall satisfaction with care (P = .019), and participating physicians reported higher levels of satisfaction with the groups than with individual care. No differences were observed between groups on self-reported health and functional status. Cost of care per member per month was $14.79 less for the group participants. CONCLUSIONS: Group visits for chronically ill patients reduce repeat hospital admissions and emergency care use, reduce cost of care, deliver certain preventive services more effectively, and increase patient and physician satisfaction.

Aged↗
PubMed1997

Proliferin transport and binding in the mouse fetus.

Proliferin (PLF), a member of the PRL/GH family secreted by the placenta, can be detected in both the maternal and fetal compartments. We now show that PLF immunoreactivity can be detected in association with the yolk sac, consistent with the transport of PLF across this structure into the amniotic fluid. Furthermore, PLF is transported across the extraembryonic membranes in isolated conceptuses that are placed in culture, and specific binding sites for PLF are detected in these embryos. The major binding sites for PLF in the cultured conceptus correspond to sites at which endogenous PLF localizes in the fetus, including developing vertebral and vascular structures. Similar binding patterns were also detected for PLF that was incubated with fetal sections. Competition and comparative binding studies indicate that the insulin-like growth factor II/mannose 6-phosphate receptor is involved in PLF binding to specific cells in the fetus. These results suggest that in addition to the effects of PLF in the placenta on neovascularization and in the maternal uterus on cell proliferation, PLF may also act at specific sites in the developing fetus.

Animals↗
PubMed1997

Fibroblast growth factor receptor signalling has a role in lobuloalveolar development of the mammary gland.

We have used the mouse mammary tumor virus promoter to express two dominant negative (DN) fibroblast growth factor receptor (FGFR) isoforms in the mammary epithelium of transgenic mice. While expression of DN-FGFR1(IIIc) showed no discernible phenotype, a similar kinase negative form of FGFR2(IIIb) caused a marked impairment of lobuloalveolar development. The growth retardation was apparent by mid-pregnancy and persisted in the post-partum glands. Despite the substantial underdevelopment of the mammary gland there was a measurable lactational response, but it was insufficient to properly sustain the new-born pups. These findings demonstrate that fibroblast growth factor signalling is necessary for pregnancy dependent lobuloalveolar development of the mammary gland.

Animals↗
PubMed1997

Lactate accumulation in the shell of the turtle Chrysemys picta bellii during anoxia at 3&deg;C and 10&deg;C

Lactate concentrations were measured in the shell and plasma of the turtle Chrysemys picta bellii after 3 months of submergence anoxia at 3&deg;C and during and after 9 days of submergence anoxia at 10&deg;C. Liver and skeletal muscle lactate levels were also measured in control and anoxic animals at each temperature. At 3&deg;C, mean shell lactate concentration (N=4) reached 133mmolkg-1shellmass and plasma lactate levels were 144mmoll-1; at 10&deg;C, shell and plasma lactate concentrations (N=5) rose in parallel during anoxic exposure, to 70.8mmolkg-1shellmass and 78.9mmoll-1, respectively, and returned in parallel to control levels during 9 days of recovery. At the end of the anoxic periods, an estimated 44% of the total body lactate resided in the shell at 3&deg;C and 43% at 10&deg;C, and indirect evidence suggests that the shell buffered these same fractions of the acid load. Because of the high lactate concentration per kilogram of shell water (416mmolkg-1 at 3&deg;C; 221mmolkg-1 at 10&deg;C) and the known formation of calcium lactate complexes, it is postulated that most of the lactate existed in the shell in combined form. I conclude that sequestration of lactate within the shell represents a potentially major adaptation to anoxic acidosis for this animal and, together with the previously described release of shell carbonates, may account for up to two-thirds of the total lactic acid buffering in this animal.

Journal Article↗
PubMed1997

Feminism: a path to clinical knowledge development.

Nurses are under increasing pressure to defend the efficacy, value and cost benefits of professional nursing care. Now more than ever, there is a need for nurses to undertake quality clinical research, through which practice may be shaped and guided. Feminist theory can provide a lens through which nurses may explore clinical issues. It also provides a framework by which socially constructed differences, such as gender and culture, may be incorporated into the design of clinical research projects. Because feminism is an openly political and transformative process, feminist concepts are suitable for use where the aim of the research is to catalyse practice change. This paper explores the use of feminism as a theoretical framework for nursing research.

Clinical Competence↗
PubMed1997

More than motherhood? A feminist exploration of 'women's health' in papers indexed by CINAHL 1993-1995.

Holism is claimed to be the signifying feature that sets women's health apart from traditional approaches to health care. As such, articles published in the nursing literature about women's health would, one might expect, reflect the centrality of holism to women's health care nursing. The findings of a study which examined the content and the focus of articles published about women's health in journals indexed by CINAHL in the period 1993-1995 challenge this assumption. It was found that women's health is a taken-for-granted notion and is used interchangeably and synonymously to refer to reproductive health, maternal health, neonatal health, family health and (hetero) sexual health. Confounding the view that holism is foundational to a women's health perspective, the papers forming the study's sample largely depict issues to do with women's health from a narrow and stereotypical perspective and with a bio-medical focus. Women were referred to as fragmented bodies, body parts and diseases, and were depicted as being passive and silent. By contrast, the voice (and the activity) of nurses and nursing's imperative to intervene was clearly discernible.

Authorship↗
PubMed1996

Mucosal addressin cell adhesion molecule-1: a structural and functional analysis demarcates the integrin binding motif.

The leukocyte integrin receptor, alpha 4 beta 7, and the mucosal addressin cell adhesion molecule-1 (MAdCAM-1) are postulated to be important in regulating lymphocyte trafficking to normal intestine. Here we provide the first description of MAdCAM-1 expression in inflamed intestine. Using mouse models of experimentally induced colitis, we show a concordant increase in MAdCAM-1 expression associated with increased cellular infiltrates in areas of intestinal inflammation. To understand more of the molecular nature of the interactions between MAdCAM-1 and its leukocyte ligand, the alpha 4 beta 7 integrin receptor, we have analyzed the structural and functional properties of chimeric recombinant MAdCAM-1 proteins in vitro. Using site-directed mutagenesis and molecular modeling, we demarcate the alpha 4 beta 7 binding motif as three linear residues within the C-D loop in the first domain of MAdCAM-1. Mutation of residue L40, D41, or T42 in the first domain completely abrogates alpha 4 beta 7+ cell binding and cellular activation. Mutagenesis of other residues in the first domain do not impact these functions. We have modeled peptides based on the predicted structure of the alpha 4 beta 7 integrin binding motif on MAdCAM-1 and are able to show specific and selective blocking of cell binding. These observations suggest that the amino acid residues LDT on MAdCAM-1 play a role in the interaction with alpha 4 beta 7 in cell adherence and cell activation.

Amino Acid Sequence↗
PubMed1996

Designing leaves. Plant morphogenesis.

Leaf shape and architecture vary greatly throughout the plant kingdom, and even within an individual plant during different phases of growth. Now, the development of a compound leaf architecture in tomato has been shown to be associated with the expression of the knotted1 homeobox gene in leaf primordia.

Genes, Homeobox↗
PubMed1996

Glycohydrolases as markers of hepatic ischemia-reperfusion injury and recovery.

Advances in liver surgery and transplantation have lead to a steady increase in the number of these interventions. Prompt quantitative assessment of hepatic of hepatic function and a patient's subsequent morbidity and mortality following surgery remain difficult despite the currently utilized historic markers of hepatic parenchymal injury (e.g., aspartate transaminase [AST], lactate dehydrogenase [LDH] gamma-glutamyl transpeptidase [GGT]). Increases in serum glycohydrolase activities appear to provide sensitive and quantitative markers of hepatic ischemia/reperfusion injury. In 10 male swine (25 to 35 kg body weight) following 30, 45, and 90 minutes of acute hepatic ischemia, the systemic release of eight different glycohydrolases and lipid peroxides into serum were determined and compared with pre- and postischemic serum levels of LDH, GGT, and AST. The rapid release of glycohydrolases into serum was directly proportional to the length of the ischemic period from 30 to 90 minutes; e.g., beta-glucosidase, mean 1.9-fold increase at 30 minutes; 8.3-fold at 45 minutes; and 22.8-fold at 90 minutes; P < .002) and the activities peaked within the first 3 hours postischemia. In constrast, AST, LDH, and GGT were released slowly and peaked 20 to 30 hours after hepatic blood flow was restored. In swine with fatal outcomes (90 minutes of ischemia), all enzyme levels increased continuously during the final hours of life. However, in swine that survived hepatic ischemia/reperfusion injury (45 minutes of ischemia) the glycohydrolases, but not AST, LDH, and GGT, declined after 2 to 3 hours' postischemia and the serum lipid peroxide levels followed the same pattern. Serum beta-galactosidase and beta-glucosidase levels are sensitive markers that rise as quickly as traditional enzyme markers (AST, LDH, GGT) following hepatic ischemic injury; moreover, the glycohydrolases have the added value of serving as predictors of survival.

Acid Phosphatase↗