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Biomedical subjects

S M Morris

Publications and source records attributed to S M Morris.

At least 37 records · Page 2Linked to original sources
PubMed2001

Induction of arginases I and II in cornea during herpes simplex virus infection.

Induction of inducible nitric oxide synthase (iNOS) following corneal infection with herpes simplex virus type-1 (HSV-1) generates nitric oxide (NO), an important player in the defense against viral infection. Changes in arginine metabolism during infection are not limited to effects of iNOS but can also involve arginases, which can modulate NO synthesis and produce ornithine for the generation of polyamines and proline. The latter are important molecules involved in tissue damage and repair during inflammation. In this study we determined the responses of arginase I and II in a murine model of HSV-1-induced stromal keratitis (HSK). In the cornea iNOS and arginase II mRNA were co-induced as the initial inflammation developed at 2 days postinfection (p.i.). As stromal keratitis progressed (days 8-15 p.i.) arginase I mRNA was induced tenfold, in contrast to a moderate decrease in arginase II and a loss of iNOS expression. These results suggest that elevated expression of arginase I and II in the cornea at late stages of ocular HSV-1 infection may play a role in lesion expression in HSK.

Animals↗
PubMed2001

Disabled-2 colocalizes with the LDLR in clathrin-coated pits and interacts with AP-2.

Disabled-2 (Dab2) is a widely expressed relative of Disabled-1, a neuron-specific signal-transduction protein that binds to and receives signals from members of the low-density lipoprotein receptor (LDLR) family. Members of the LDLR family internalize through clathrin-coated pits and vesicles to endosomes, from where they return to the cell surface through the secretory pathway. In this study, we show that the Dab2 phosphotyrosine-binding domain binds peptides containing the sequence FXN-PXY. This core sequence is found in the intracellular domains of LDLR family members and is important for receptor internalization. Dab2 transiently colocalizes with the LDLR in clathrin-coated pits, but is absent from endosomes and lysosomes. Dab2 is alternatively spliced and its localization depends on a region of the protein that contains two DPF motifs that are present in the p96 Dab2 protein and absent in the p67 splice variant. This region is sufficient to confer Dab2 binding to the alpha-adaptin subunit of the clathrin adaptor protein, AP-2. Overexpression of p96 but not of p67 Dab2 disrupts the localization of AP-2. These findings suggest that in addition to previously reported signal-transduction functions, Dab2 could also act as an adaptor protein that may regulate protein trafficking.

3T3 Cells↗
PubMed2001

Informal carers of cancer patients: what are their unmet psychosocial needs?

This paper considers the significant unmet psychosocial needs of the informal carers of cancer patients, drawing on data generated in a 3-year UK study (1997-2000) on the psychosocial needs of cancer patients and their main carers. While the needs of the carers of cancer patients are increasingly being recognised in healthcare policy documents, there is relatively little published literature on these needs. A "significant unmet need" is defined here as a need deemed important by the carer, but which has not been met. A descriptive cross-sectional survey of carers was conducted and the responses of 195 carers relating to 48 psychosocial need items were analysed. A subset of these carers (n = 32) were interviewed. Forty-three per cent of carers had significant unmet needs. They were more likely to be those where the relationship to the patient was not that of a partner or spouse, more likely to have other caring responsibilities, and less likely to have friends or relations to call upon for help. Carers with unmet needs were also more likely to be in poor health themselves or to be caring for a patient who had reached the palliation-only phase in their cancer journey. The majority of carers expressed the importance of needs such as having good relationships with healthcare professionals and receiving honest information, but few expressed dissatisfaction with these aspects of need. Items of significant unmet need clustered around aspects of managing daily life, emotions, and also social identity for a sizeable minority of carers. These are the same areas of significant unmet need that concern patients. However, carers have more of these concerns, reflecting their comparative neglect. The paper also considers how these widespread concerns can be addressed.

Caregivers↗
PubMed2001

The carer's place in the cancer situation: where does the carer stand in the medical setting?

Recent thinking about policy on cancer services in the UK has highlighted the importance of recognising the needs of carers, but is unclear about the ways in which this might be done. Our recent study on the psychosocial needs of cancer patients and their main informal carers was unusual in its combined focus on patients and carers experiencing the 'cancer journey' together. One of our aims was to contribute to an understanding of what it means to be the main carer of someone with cancer. Using the qualitative data from the 79 carers and patients we interviewed, we ask how carers negotiate their place in the cancer situation, and particularly how do carers identify their role in relation to the patient and the medical setting? We posit carers as taking part in a shifting process of 'carerhood' in which competing needs vie for space. Our evidence suggests carers actively negotiate the challenges of their position in dealing with issues of identity, support, and sharing. We suggest that when the carer's involvement in the cancer scenario is recognised and legitimised by others it is easier for them to attend to their own needs alongside those of the patient.

Caregivers↗
PubMed2001

Arginase I expression and activity in human mononuclear cells after injury.

OBJECTIVE: To determine the effect of trauma on arginase, an arginine-metabolizing enzyme, in cells of the immune system in humans. SUMMARY BACKGROUND DATA: Arginase, classically considered an enzyme exclusive to the liver, is now known to exist in cells of the immune system. Arginase expression is induced in these cells by cytokines interleukin (IL) 4, IL-10, and transforming growth factor beta, corresponding to a T-helper 2 cytokine profile. In contrast, nitric oxide synthase expression is induced by IL-1, tumor necrosis factor, and gamma interferon, a T-helper 1 cytokine profile. Trauma is associated with a decrease in the production of nitric oxide metabolites and a state of immunosuppression characterized by an increase in the production of IL-4, IL-10, and transforming growth factor beta. This study tests the hypothesis that trauma increases arginase activity and expression in cells of the immune system. METHODS: Seventeen severely traumatized patients were prospectively followed up in the intensive care unit for 7 days. Twenty volunteers served as controls. Peripheral mononuclear cells were isolated and assayed for arginase activity and expression, and plasma was collected for evaluation of levels of arginine, citrulline, ornithine, nitrogen oxides, and IL-10. RESULTS: Markedly increased mononuclear cell arginase activity was observed early after trauma and persisted throughout the intensive care unit stay. Increased arginase activity corresponded with increased arginase I expression. Increased arginase activity coincided with decreased plasma arginine concentration. Plasma arginine and citrulline levels were decreased throughout the study period. Ornithine levels decreased early after injury but recovered by postinjury day 3. Increased arginase activity correlated with the severity of trauma, early alterations in lactate level, and increased levels of circulating IL-10. Increased arginase activity was associated with an increase in length of stay. Plasma nitric oxide metabolites were decreased during this same period. CONCLUSIONS: Markedly altered arginase expression and activity in cells of the human immune system after trauma have not been reported previously. Increased mononuclear cell arginase may partially explain the benefit of arginine supplementation for trauma patients. Arginase, rather than nitric oxide synthase, appears to be the dominant route for arginine metabolism in immune cells after trauma.

Adult↗
PubMed2001

Alterations in arginine metabolic enzymes in trauma.

Arginine is the sole substrate for nitric oxide (NO) synthesis by NO synthases (NOS) and promotes the proliferation and maturation of human T-cells. Arginine is also metabolized by the enzyme arginase, producing urea and ornithine, the precursor for polyamine production. We sought to determine the molecular mechanisms regulating arginase and NOS in splenic immune cells after trauma. C3H/HeN mice underwent laparotomy as simulated moderate trauma or anesthesia alone (n = 24 per group). Six, 12, 24, or 48 h later, 6 animals from each group were sacrificed, and splenectomy was performed and plasma collected. Six separate animals had neither surgery nor anesthesia and were sacrificed to provide resting values (t = 0 h). Spleen arginase I and II and iNOS mRNA abundance, arginase I protein expression, and arginase activity were determined. Plasma NO metabolites (nitrite + nitrate) were also measured. Trauma increased spleen arginase I protein expression and activity (P = 0.01) within 12 and for at least 48 h after injury and coincided with up-regulated arginase I mRNA abundance at 24 h. Neither arginase II nor iNOS mRNA abundance in the spleen was significantly increased by trauma at 24 h. Plasma nitrite + nitrate was decreased in animals 48 h post-injury compared to anesthesia controls (P < 0.05). Trauma induces up-regulation of arginase I gene expression in splenic immune cells within 24 h of injury. Arginase II is not significantly up-regulated at that time point. Arginase I, rather than iNOS appears to be the dominant route for arginine metabolism in splenic immune cells 24 h after trauma.

Animals↗
PubMed2001

Generation of a mouse model for arginase II deficiency by targeted disruption of the arginase II gene.

Mammals express two isoforms of arginase, designated types I and II. Arginase I is a component of the urea cycle, and inherited defects in arginase I have deleterious consequences in humans. In contrast, the physiologic role of arginase II has not been defined, and no deficiencies in arginase II have been identified in humans. Mice with a disruption in the arginase II gene were created to investigate the role of this enzyme. Homozygous arginase II-deficient mice were viable and apparently indistinguishable from wild-type mice, except for an elevated plasma arginine level which indicates that arginase II plays an important role in arginine homeostasis.

Amino Acids↗
PubMed2001

Regulatory role of arginase I and II in nitric oxide, polyamine, and proline syntheses in endothelial cells.

Endothelial cells (EC) metabolize L-arginine mainly by arginase, which exists as two distinct isoforms, arginase I and II. To understand the roles of arginase isoforms in EC arginine metabolism, bovine coronary venular EC were stably transfected with the Escherichia coli lacZ gene (lacZ-EC, control), rat arginase I cDNA (AI-EC), or mouse arginase II cDNA (AII-EC). Western blots and enzymatic assays confirmed high-level expression of arginase I in the cytosol of AI-EC and of arginase II in mitochondria of AII-EC. For determining arginine catabolism, EC were cultured for 24 h in DMEM containing 0.4 mM L-arginine plus [1-(14)C]arginine. Urea formation, which accounted for nearly all arginine consumption by these cells, was enhanced by 616 and 157% in AI-EC and AII-EC, respectively, compared with lacZ-EC. Arginine uptake was 31-33% greater in AI-EC and AII-EC than in lacZ-EC. Intracellular arginine content was 25 and 11% lower in AI-EC and AII-EC, respectively, compared with lacZ-EC. Basal nitric oxide (NO) production was reduced by 60% in AI-EC and by 47% in AII-EC. Glutamate and proline production from arginine increased by 164 and 928% in AI-EC and by 79 and 295% in AII-EC, respectively, compared with lacZ-EC. Intracellular content of putrescine and spermidine was increased by 275 and 53% in AI-EC and by 158 and 43% in AII-EC, respectively, compared with lacZ-EC. Our results indicate that arginase expression can modulate NO synthesis in bovine venular EC and that basal levels of arginase I and II are limiting for endothelial syntheses of polyamines, proline, and glutamate and may have important implications for wound healing, angiogenesis, and cardiovascular function.

Animals↗
PubMed2001

Building Elastin. Incorporation of recombinant human tropoelastin into extracellular matrices using nonelastogenic rat-1 fibroblasts as a source for lysyl oxidase.

The purpose of this study was to assess the feasibility of crosslinking exogenously produced tropoelastin, the precursor of insoluble elastin, into existing elastin. Tritiated recombinant human tropoelastin (rhTE) was added to neonatal rat aorta smooth-muscle cell (NNRSMC) cultures. As much as 12% of the added rhTE was incorporated into the NNRSMC-derived insoluble elastin with the formation of the elastin crosslinks desmosine (DES) and isodesmosine (IDES) in a time-dependent fashion. The ratio of radioactivity found in DES and IDES crosslinks to that found in lysyl residues increased from 0.18 immediately after incubation with rhTE to 0.76 after 14 d. Crosslinking of rhTE into elastin and the accompanying formation of tritiated water was inhibited by beta-aminoproprionitrile, a potent inhibitor of lysyl oxidase, an enzyme critical for the post-translational processing of elastin and collagen. Acellular NNRSMC matrices were produced and replated with Rat-1 fibroblasts, cells that were found to express lysyl oxidase but not tropoelastin. At 14 d after incubation with rhTE, the ratio of DES and IDES radioactivity to that of lysine in the insoluble elastin was 0.38. We show for the first time that cells expressing lysyl oxidase, but not elastin, as well as elastogenic cells can incorporate rhTE into insoluble elastin with the formation of elastin crosslinks. This novel approach might be used to augment elastin repair in certain pathologic states.

Animals↗
PubMed2001

Joint and individual interviewing in the context of cancer.

Joint interviewing lies somewhere between individual in-depth interviews and focus groups in the panoply of qualitative methodology, yet it has been little explored or described in health research. This article sets out to reflect on the process of choosing to combine joint and individual interviews in the context of a study on the needs of cancer patients and their carers. Questions of intrusion, inclusion, power, and difference caused the researchers to refine their research methods and become more responsive to the preferences of their participants. The article goes on to describe the kind of data generated by joint interviewing and to consider questions of analysis. The author concludes by suggesting that in appropriate circumstances, joint interviewing offers a valuable method of enquiry.

Adult↗
PubMed2001

NUDC expression during amphibian development.

To identify gene products important for gastrulation in the amphibian Pleurodeles waltl, a screen for regional differences in new protein expression at the early gastrula stage was performed. A 45 kDa protein whose synthesis was specific for progenitor endodermal cells was identified. Microsequencing and cDNA cloning showed that P45 is highly homologous to rat NUDC, a protein suggested to play a role in nuclear migration. Although PNUDC can be detected in all regions of the embryo, its de novo synthesis is tightly regulated spatially and temporally throughout oogenesis and embryonic development. New PNUDC synthesis in the progenitor endodermal cells depends on induction by the mesodermal cells in the gastrula. During development, PNUDC is localized in the egg cortical cytoplasm, at the cleavage furrow during the first embryonic division, around the nuclei and cortical regions of bottle cells in the gastrula, and at the basal region of polarized tissues in the developing embryo. These results show for the first time the expression and compartmentalization of PNUDC at distinct stages during amphibian development.

Amino Acid Sequence↗
PubMed2000

Induction of arginase II in human Caco-2 tumor cells by cyclic AMP.

The objective of this study was to elucidate the mechanism by which cyclic AMP increases arginase activity in cultured human Caco-2 tumor cells. Caco-2 cells were incubated for 24 h in the presence of 8-bromo cyclic AMP or forskolin, and the cells were harvested, lysed, and assayed for total arginase activity. Both test agents increased arginase activity by twofold, and this was attributed to the induction of the arginase II isoform. Both arginase II mRNA and protein showed increased expression in response to 8-bromo cyclic AMP and forskolin, and these effects were inhibited by H-89 (protein kinase A inhibitor), enhanced by okadaic acid (phosphatase inhibitor), and enhanced by 1-methyl-3-isobutylxanthine (cyclic nucleotide phosphodiesterase inhibitor). Cyclic GMP did not appear to be involved in arginase II induction. These observations indicate that cyclic AMP stimulates arginase II gene expression by mechanisms involving activation of protein kinase A and consequent activation of appropriate transcription factors.

1-Methyl-3-isobutylxanthine↗
PubMed2000

Intraoperative topical tetracycline sclerotherapy following mastectomy: a prospective, randomized trial.

BACKGROUND AND OBJECTIVES: Postoperative wound seromas are a frequent and troublesome occurrence after mastectomy. Recent reports have suggested the efficacy of topical sclerosants at reducing their formation. METHODS: A prospective, randomized, double-blinded trial was performed to examine the effect of intraoperatively administered topical tetracycline on the occurrence of postoperative mastectomy seromas. Thirty-two women were randomized to the control arm (normal saline) and 30 women to the tetracycline arm. In the treatment group, 100 ml (2 g) of tetracycline solution was administered topically to the chest wall and skin flaps prior to skin closure. The control group received an equal volume of normal saline. Patients were monitored for the development of postoperative wound seroma. RESULTS: There were no significant differences between groups regarding total volume of closed suction drainage, numbers of patients leaving hospital with drains in place, or duration of catheter drainage. Seroma formation 2 weeks postoperatively was greater in the tetracycline group than the control group (53% vs. 22%, P = 0.01). There were no differences between groups regarding the degree of postoperative pain, wound infection, or seroma formation 1 month postoperatively. CONCLUSIONS: Topical tetracycline is not effective at preventing post-mastectomy wound seromas.

Administration, Topical↗
PubMed2000

Autoantibody recognition of distinctly modified forms of the U1-70-kd antigen is associated with different clinical disease manifestations.

OBJECTIVE: To examine whether autoantibody recognition of modified forms of the U1-70-kd RNP antigen correlates with manifestations of rheumatic disease. METHODS: Blinded to clinical disease manifestations, sera from 27 rheumatic disease patients with U1-70-kd antibodies were used to immunoblot control, apoptotic, and oxidatively modified HeLa cell lysates. Using densitometry, recognition of antigen fragments was quantitated. The presence or absence of 1) lupus skin disease and 2) Raynaud's phenomenon (RP) was determined for each patient by chart review. The ability of patient sera to recognize the different fragments was compared for patients with and without skin disease and with and without RP. RESULTS: Patients with lupus skin disease had higher recognition of apoptotic U1-70 kd than did patients without skin disease (mean +/- SD fragment recognition index [FRI] 1.35 +/- 0.57 versus 0.95 +/- 0.25; P < 0.024, by Student's t-test). Patients with RP had higher recognition of oxidatively modified U1-70 kd than did patients without RP (mean +/- SD FRI 0.95 +/- 0.80 versus 0.24 +/- 0.22; P < 0.048). CONCLUSION: Recognition of apoptotically and oxidatively modified forms of the U1-70-kd autoantigen are associated with distinct clinical rheumatic disease manifestations. This finding provides in vivo evidence for the hypothesis that immune recognition of modified forms of self antigens may be relevant to the pathogenesis of systemic rheumatic diseases. Understanding the antigenic modifications to which patients react may help predict the expression of rheumatic syndromes.

Antigens↗
PubMed2000

cAMP induces CD14 expression in murine macrophages via increased transcription.

CD14, a glycoprotein that binds bacterial lipopolysaccharide, plays a critical role in the inflammatory response to infection by gram-negative bacteria. Studies were undertaken to determine whether cyclic adenosine monophosphate (cAMP) regulates CD14 expression in macrophages. Incubation of RAW 264.7 cells with 8-Br-cAMP resulted in a significant increase in steady-state CD14 mRNA levels. The increase in mRNA levels was also associated with both cell-associated and soluble CD14 protein. H89 completely blocked the 8-Br-cAMP-induced CD14 mRNA up-regulation. There was no change in CD 14 mRNA half-life in the presence of 8-Br-cAMP. The CD14 gene transcription rate was increased about twofold after exposure to 8-Br-cAMP. cAMP-dependent increases in CD14 mRNA were also observed in rat peritoneal macrophages, demonstrating that this is an authentic response of mature macrophages. This study provides evidence that cAMP and protein kinase A are important regulators of CD14 expression in macrophages.

1-Methyl-3-isobutylxanthine↗
PubMed2000

Trauma increases extrahepatic arginase activity.

BACKGROUND: Although expressed primarily in the liver, arginase activity also is present in extrahepatic tissues and specifically in macrophages, where it may play diverse physiologic roles in wound healing, cellular proliferation, and the regulation of nitric oxide production. Arginase activity in immune cells is upregulated by certain cytokines such as IL-4, IL-10, and TGF-beta and by catecholamines. Since the release of these substances is increased after trauma, we hypothesized that arginase activity would also be increased in immune cells after trauma. The current work tests this hypothesis. METHODS: A model of surgical trauma was created in C3H/HeN mice by performing an exploratory laparotomy. Tissue arginase activity and arginase I protein expression were determined. As a control, arginase activity and expression were also stimulated with the use of endotoxin. In addition, we evaluated the expression of inducible nitric oxide synthase and the accumulation of nitric oxide metabolites in plasma. RESULTS: Surgical trauma was associated with a significant increase in arginase activity in splenic and renal tissues (P < .05). Splenic macrophages from trauma animals exhibited arginase activity levels approximately 10 times those of controls (P < .05). Endotoxin alone increased arginase activity in the spleen, but this increase was less than that of trauma alone (P < .05). Arginase activity remained elevated after trauma for up to 4 days and normalized by day 7. Arginase I expression was upregulated by trauma in both splenic and renal tissue and by endotoxin in the spleen only. Despite upregulation of inducible nitric oxide synthase in trauma animals, circulating nitric oxide metabolites were decreased 2 days after trauma compared with controls (P < .05). Endotoxin-induced nitric oxide metabolites were also reduced in trauma animals compared with endotoxin treatment alone (P < .05), but this normalized by day 4. CONCLUSIONS: Extrahepatic arginase expression and activity is increased after trauma and may provide the necessary precursors for cellular proliferation and repair or may play a regulatory role in the production of nitric oxide.

Animals↗
PubMed2000

A cortisol surge mediates the enhanced expression of pig intestinal pyrroline-5-carboxylate synthase during weaning.

Citrulline synthesis from glutamine is enhanced remarkably in enterocytes of weanling pigs, but the molecular mechanism(s) involved are not known. The objective of this study was to determine whether a cortisol surge mediates the enhanced expression of intestinal citrulline-synthetic enzymes during weaning. Jejunal enterocytes were prepared from 29-d-old weanling pigs treated with or without metyrapone (an inhibitor of cortisol synthesis), or from age-matched unweaned pigs. The mRNA levels and activities of phosphate-dependent glutaminase (PDG), pyrroline-5-carboxylate synthase (P5CS), ornithine aminotransferase (OAT), carbamoyl-phosphate synthase I (CPS-I) and ornithine carbamoyltransferase (OCT) were determined. The mRNA levels for PDG, P5CS, OAT and OCT were 139, 157, 102 and 55% higher, respectively, in weanling pigs compared with suckling pigs. The activities of PDG and P5CS were 38 and 692% higher, respectively, in weanling pigs compared with unweaned pigs, but the activities of OAT, CPS-I and OCT did not differ between these two groups of pigs. The effects of metyrapone administration to weanling pigs were as follows: 1) prevention of a cortisol surge, 2) abolition of the increases in both mRNA levels and activity of P5CS, 3) no alteration in the mRNA levels and activities of PDG and CPS-I, 4) increases in the mRNA levels for OAT (216%) and OCT (39%) and in OAT activity (30%), and 5) prevention of the increase in intestinal synthesis of citrulline from glutamine. These results suggest that increased P5CS activity reflects in large part the increased levels of P5CS mRNA and is responsible for the increased synthesis of citrulline from glutamine in enterocytes of weanling pigs; these increases may be mediated by a cortisol surge during weaning that can be blocked by metyrapone administration.

Animals↗