Antisense expression of an Arabidopsis ran binding protein renders transgenic roots hypersensitive to auxin and alters auxin-induced root growth and development by arresting mitotic progress

We cloned a cDNA encoding an Arabidopsis Ran binding protein, AtRanBP1c, and generated transgenic Arabidopsis expressing the antisense strand of the AtRanBP1c gene to understand the in vivo functions of the Ran/RanBP signal pathway. The transgenic plants showed enhanced primary root growth but suppressed growth of lateral roots. Auxin significantly increased lateral root initiation and inhibited primary root growth in the transformants at 10 pM, several orders of magnitude lower than required to induce these responses in wild-type roots. This induction was followed by a blockage of mitosis in both newly emerged lateral roots and in the primary root, ultimately resulting in the selective death of cells in the tips of both lateral and primary roots. Given the established role of Ran binding proteins in the transport of proteins into the nucleus, these findings are consistent with a model in which AtRanBP1c plays a key role in the nuclear delivery of proteins that suppress auxin action and that regulate mitotic progress in root tips.

The role of IL-1beta in the regulation of IL-8 and IL-6 in human corneal epithelial cells during Pseudomonas aeruginosa colonization

PURPOSE

Recent studies have shown that the levels of interleukin (IL)-1beta, IL-6 and IL-8 are associated with the severity of infectious diseases. The purpose of this study was to investigate whether IL-1beta regulates the expression of IL-6 and IL-8 in human corneal epithelial cells during Pseudomonas aeruginosa colonization.

METHODS

Confluent immortalized human corneal epithelial cells were challenged with P. aeruginosa 6294 in the presence of anti-human IL-1beta antibody or matched control antibody. The cells were also challenged with recombinant IL-1beta protein without bacterial colonization. Expression of IL-1beta, IL-6 and IL-8 mRNA and protein was detected by reverse transcription (RT)-PCR and by enzyme-linked immunosorbent assay (ELISA), respectively. IL-1beta localization was determined by immunohistochemistry.

RESULTS

Human corneal epithelial cells expressed low levels of IL-1beta and high levels of IL-6 and IL-8 during P. aeruginosa colonization. Addition of IL-1beta Ab resulted in a significant decrease (P < 0.05) in IL-8 protein expression at 4 h, 8 h and 12 h. Addition of IL-1beta Ab reduced IL-6 protein expression at 8 h and increased IL-6 protein expression at 12 h. Addition of recombinant IL-1beta protein alone strongly stimulated the expression of IL-8 and IL-6. Immunohistochemical staining showed that IL-1beta protein was present both intracellularly and extracellularly in P. aeruginosa colonized cells.

CONCLUSIONS

IL-1beta is able to modulate expression of both IL-6 and IL-8 at transcriptional and post-transcriptional levels in human corneal epithelial cells.

Impact of long-term complications on quality of life in patients with type 2 diabetes not using insulin

OBJECTIVES

The complications of diabetes have the potential to greatly impact the health-related quality of life (HRQOL) of patients with type 2 diabetes. The effect of diabetic complications on HRQOL was assessed in 1233 patients with type 2 diabetes who were not using insulin.

METHODS AND DATA

Patients were aged 35 and older and had stable fasting serum glucose (FSG) after washout of antidiabetic therapy. Patients who required insulin or suffered from severe cardiovascular or hepatic disease, neuropathy, or retinopathy were excluded. Patients completed the SF-36 generic quality of life questionnaire. Demographic data, including body mass index (BMI), blood glucose hemoglobin A1c (HbA1c), FSG, and the presence and severity of eight specified diabetic complications were also collected. A linear regression analysis was performed for each of the SF-36 domains and for the physical and mental health summary scales.

RESULTS

The most prevalent diabetic complications were hypertension (46% of patients), peripheral sensory neuropathy (PSN; 12%), coronary artery disease (CAD; 8%), retinopathy (8%), and peripheral vascular disease (PVD; 7%). Most (73%) of the complications were assessed to be mild. PSN was associated with significantly lower scores (i.e., worse quality of life) in the mental health scale; CAD was associated with significant reductions of all but role-emotional and mental health scales of the SF-36; and PVD was associated with significantly lower physical and social functioning scales. Hypertension did not have an independent effect on HRQOL.

CONCLUSIONS

The presence of even mild diabetic complications has a significant impact on patients' quality of life. Early diagnosis and treatment is essential to help prevent deterioration of HRQOL in these patients.

Reliability and sensitivity of joint space measurements in hand radiographs using computerized image analysis

OBJECTIVE

To establish the sensitivity and reliability of proximal interphalangeal (PIP) and metacarpophalangeal (MCP) mean joint space measurements using standard clinical radiographs of healthy subjects, in order to determine the limits at which a change in radiographic joint space could indicate a change in actual joint size.

METHODS

Repeat hand radiographs of healthy subjects were taken using standard techniques at 3-5 day intervals with the hands flat (5 posteroanterior radiographs in 8 subjects) or in 6 different flexed positions on a single occasion (8 subjects). The mean joint space was determined using custom soft ware and was validated manually. Measurement reproducibility within subjects, within films, and between hand positions was assessed by analysis of variance.

RESULTS

In repeat radiographs taken in the standard clinical position, the precision of individual join space measurements indicates that changes > 0.11 mm (approximately 7%) would represent an actual physical change in joint space width (with 95% probability). Averaging measurements across fingers for a single subject decreases the detectable change to 0.05 mm (approximately 3%). With increasing flexure, radiographic joint space tended to increase in MCP and decrease in PIP.

CONCLUSION

Mean finger joint space measured from standard clinical radiographs is a reliable and sensitive measurement in healthy subjects even with some change in hand position. Work is required to establish whether the joint space change measured from serial radiographs of patients with arthritis over a period of 6-12 mo exceeds the detectable limits of change derived in this study.

What is chronic fatigue syndrome? Heterogeneity within an international multicentre study

OBJECTIVE

We sought to compare the characteristics of patients presenting with chronic fatigue (CF) and related syndromes in eight international centres and to subclassify these subjects based on symptom profiles. The validity of the subclasses was then tested against clinical data.

METHOD

Subjects with a clinical diagnosis of CF completed a 119-item self-report questionnaire to provide clinical symptom data and other information such as illness course and functional impairment. Subclasses were generated using a principal components-like analysis followed by latent profile analysis (LPA).

RESULTS

744 subjects returned complete data sets (mean age 40.8 years, mean length of illness 7.9 years, female to male ratio 3:1). Overall, the subjects had a high rate of reporting typical CF symptoms (fatigue, neuropsychological dysfunction, sleep disturbance). Using LPA, two subclasses were generated. Class one (68% sample) was characterized by: younger age, lower female to male ratio; shorter episode duration; less premorbid, current and familial psychiatric morbidity; and, less functional disability. Class two subjects (32%) had features more consistent with a somatoform illness. There was substantial variation in subclass prevalences between the study centres (Class two range 6-48%).

CONCLUSIONS

Criteria-based approaches to the diagnosis of CF and related syndromes do not select a homogeneous patient group. While substratification of patients is essential for further aetiological and treatment research, the basis for allocating such subcategories remains controversial.

Impact of clinical reverse transcriptase sequences on the replication capacity of HIV-1 drug-resistant mutants

We have shown that the HIV-1 laboratory strain NL4-3 that contains P236L [a reverse transcriptase mutation conferring resistance to the nonnucleoside reverse transcriptase inhibitor (NRTI) delavirdine] replicates more slowly than wild-type NL4-3. Other NNRTI-resistance mutations, such as K103N and Y181C, do not reduce the replication capacity of NL4-3 as much as P236L and develop more frequently in HIV-1 isolates from patients failing delavirdine. However, a minority of patients on delavirdine therapy still have isolates with P236L. We postulated that reverse transcriptase (RT) sequences from these patient isolates contain other mutations that compensate for the adverse effect of P236L. To test this hypothesis, we created 15 chimeric NL4-3 isolates that contained delavirdine-resistant RT sequences derived from eight patient isolates and characterized their replication kinetics. Nine of 10 patient-derived clones containing P236L replicated as slowly as NL4-3 with P236L. In contrast, three of five clones that did not have P236L (but had either K103N or Y181C) replicated significantly better than NL4-3 with P236L. Thus, the majority of patients who acquire P236L during delavirdine therapy do not have RT mutations that compensate for the replication defect conferred by P236L. We hypothesize that HIV-1 isolates with P236L may have a compensatory mutation outside RT. Alternatively, variants of HIV-1 with reduced replication fitness may be selected during antiretroviral therapy, suggesting that stochastic events rather than viral replication fitness may determine which drug-resistant mutants emerge early during antiretroviral failure. In some isolates, it appears that the background RT sequence can contribute significantly to the replication fitness of drug-resistant HIV-1 variants.

The MCP silencer of theDrosophila Abd-Bgene requires both Pleiohomeotic and GAGA factor for the maintenance of repression

Silencing of homeotic gene expression requires the function of cis-regulatory elements known as Polycomb Response Elements (PREs). The MCP silencer element of the Drosophila homeotic gene Abdominal-B has been shown to behave as a PRE and to be required for silencing throughout development. Using deletion analysis and reporter gene assays, we defined a 138 bp sequence within the MCP silencer that is sufficient for silencing of a reporter gene in the imaginal discs. Within the MCP138 fragment, there are four binding sites for the Pleiohomeotic protein (PHO) and two binding sites for the GAGA factor (GAF), encoded by the Trithorax-like gene. PHO and the GAF proteins bind to these sites in vitro. Mutational analysis of PHO and GAF binding sequences indicate that these sites are necessary for silencing in vivo. Moreover, silencing by MCP138 depends on the function of the Trithorax-like gene, and on the function of the PcG genes, including pleiohomeotic. Deletion and mutational analyses show that, individually, either PHO or GAF binding sites retain only weak silencing activity. However, when both PHO and GAF binding sites are present, they achieve strong silencing. We present a model in which robust silencing is achieved by sequential and facilitated binding of PHO and GAF.

Regulatory role of IL-1beta in the expression of IL-6 and IL-8 in human corneal epithelial cells during Pseudomonas aeruginosa colonization

Pseudomonas aeruginosa is a virulent pathogen and is frequently associated with bacterial keratitis. Recent studies have shown that high levels of interleukin (IL)-1beta and macrophage inflammatory protein-2 are associated with the severity of corneal infection. Interleukin-1beta is a principal inflammatory mediator. Understanding the regulatory role of IL-1beta would provide better understanding of host responses during P. aeruginosa corneal infection. A human corneal epithelial (HCE) cell line and three P. aeruginosa strains were used in this experiment. Confluent HCE cells were challenged with P. aeruginosa and monoclonal antihuman IL-1beta antibody (IL-1beta mAb). The culture supernatants were collected for measuring cytotoxicity and protein levels of IL-1beta, IL-8 and IL-6 by enzyme-linked immunosorbent assay. Results showed that HCE cells expressed low levels of IL-1beta and high levels of IL-6 and IL-8 during P. aeruginosa colonization. Paer1-colonized HCE cells produced higher levels of IL-1beta, IL-6 and IL-8 protein compared to those produced by 6206- and 6294-colonized HCE cells. Administration of IL-1beta mAb decreased the production of IL-8 and IL-6. In conclusion, P. aeruginosa-colonized HCE cells produced low levels of IL-1beta and high levels of IL-6 and IL-8. Neutralizing IL-1beta protein significantly downregulated the production of IL-8 and IL-6.

Expression of macrophage migration inhibitory factor during Pseudomonas keratitis

Macrophage migration Inhibitory factor (MIF) is a recently rediscovered pro-inflammatory cytokine, and has been shown to play a role in the regulation of neutrophil chemokines and angiogenesis. Corneal epithelial and endothelial cells have been shown to express MIF. This study evaluated the expression of MIF during Pseudomonas keratitis in mice and in vitro using a corneal epithelial cell line. Three strains of P. aeruginosa, 6294 (invasive strain), 6206 (cytotoxic strain) and Paer1 (non-infectious strain) were used. Both cytotoxic and invasive strains were isolated from human corneal ulcers and the Paer1 strain was isolated from a non-infectious condition. Following challenge in mouse corneas or a corneal epithelial cell line, corneal homogenates or lysed corneal epithelial cells were used to isolate RNA. Migration inhibitory factor mRNA expression in the mouse cornea or human corneal epithelial cells was examined by reverse transcription-polymerase chain reaction analysis, and was found to be expressed as early as 4 h after the injury (scratch controls) or infection in the mouse corneas. Migration inhibitory factor mRNA in scratch controls and Paer1-inoculated corneas showed peak levels at 4 h post-challenge and this dropped by 24 h post-challenge. Corneas challenged with invasive and cytotoxic strains showed peak expression 24 h post-challenge. Migration inhibitory factor mRNA levels were significantly higher in invasive and cytotoxic strain inoculated corneas compared to Paer1 inoculated corneas. Challenging the corneal epithelial cell line with Pseudomonas 6294 and 6206 strains induced peak expression at 8 h and levels were decreased by 12 h. Epithelial cells inoculated with recombinant human interleukin-1beta protein induced very high levels of MIF mRNA at all time points compared to infected and control corneal epithelial cells. High expression of MIF in the infected corneas suggests that it may have a role in the pathogenesis of corneal disease induced by invasive and cytotoxic strains of P. aeruginosa.

The role of risk and benefit perception in informed consent for surgery

BACKGROUND

Informed consent relies on patients' ability to understand risk information. Evidence suggests that people may extract the gist of any risk information to make medical decisions. Existing evidence also suggests that there is an inverse relationship between the perception of risk and the perception of benefit.

METHOD

Seventy-one patients on the waiting list for carotid endarterectomy (CEA) were surveyed regarding their understanding and recall of the risk and benefit to health of undergoing CEA. Patients were surveyed 1 month after their initial consultation, and a subgroup was surveyed again on the day before their operation.

RESULTS

Patients' estimates of their baseline risk of stroke without surgery were significantly different from what they had been told by the surgeon. Patients' estimates of stroke risk due to surgery ranged from 0% to 65% (actual local risk 2%). Patients also had unreasonable expectations about the benefit of the operation for their health. Estimates of stroke risk correlated positively with the degree of expected benefit from the operation (r = 0.29, P = 0.05). When resurveyed the day before the operation, patients' perceptions of both risk and benefit had increased significantly. The risk perception data from some patients appeared to contradict some of the predictions of the fuzzy-trace theory.

CONCLUSIONS

Most patients failed to understand the risks and benefits associated with CEA. Some patients' estimates of stroke risk were actually greater than the perceived potential benefit of surgery in terms of risk reduction. The data also suggested a positive correlation between the degree of perceived benefit and the degree of perceived risk.

Development of an exercise expert system for older adults

The purpose of this study was to develop a computerized exercise expert system (CEES) that creates tailored exercise plans for older adults. A panel of experts was selected in the areas of medicine, exercise physiology, health promotion, exercise psychology, and gerontology. The experts communicated with the principal investigator and the project members by mail, email, telephone, and expert meetings. A two-day workshop was held during the second year for the project members as well as local and national experts to review the CEES. The CEES demonstrated adequate inter-rater reliability (0.80) and criterion validity (0.70). Content validity was achieved by literature review and expert opinion. The CEES gathers information on the elder's health status, clinical factors, and exercise determinants that characterize specific barriers or incentives to exercise. The software program then develops individualized exercise prescriptions that are customized to older adults.

Membrane impermeant antioestrogens discriminate between ligand- and voltage-gated cation channels in NG108-15 cells

Native 5-HT(3) and AChR ligand-gated cation channels can be inhibited (blocked) by the non-steroidal antioestrogen tamoxifen. However, the exact site and mechanism of inhibition by tamoxifen on these channels remain unclear. We have investigated the action of the membrane impermeant quaternary derivative, ethylbromide tamoxifen (EBT), on native ligand-gated 5-HT(3) receptor channels and voltage-gated K(+) channels in NG108-15 cells using whole cell patch clamp. Extracellular EBT inhibited whole cell cationic currents of 5-HT(3) receptors with IC(50) of 0.22+/-0.4 microM (n(H)=1.05+/-0.2). The channel block was characterised by voltage independent and use independent behaviour (similar to that of tamoxifen). EBT was unable to inhibit voltage-gated K(+) currents in NG108-15 cells. This was in contrast to the inhibition by tamoxifen which, at similar concentrations, accelerated the apparent inactivation of these outward K(+) currents. The inhibition of 5-HT(3) receptors by a membrane impermeant derivative of tamoxifen supports the view that the binding site for antioestrogens is extracellular and the inhibition is not mediated through genomic/transcriptional activity.

Monitor: molecules and profiles

Monitor provides an insight into the latest developments in drug discovery through brief synopses of recent presentations and publications together with expert commentaries on the latest technologies. There are two sections: Molecules summarizes the chemistry and the pharmacological significance and biological relevance of new molecules reported in the literature and on the conference scene; Profiles offers commentary on promising lines of research, emerging molecular targets, novel technology, advances in synthetic and separation techniques and legislative issues.

Mutants of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase resistant to nonnucleoside reverse transcriptase inhibitors demonstrate altered rates of RNase H cleavage that correlate with HIV-1 replication fitness in cell culture

Three mutants of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (V106A, V179D, and Y181C), which occur in clinical isolates and confer resistance to nonnucleoside reverse transcriptase inhibitors (NNRTIs), were analyzed for RNA- and DNA-dependent DNA polymerization and RNase H cleavage. All mutants demonstrated processivities of polymerization that were indistinguishable from wild-type enzyme under conditions in which deoxynucleoside triphosphates were not limiting. The V106A reverse transcriptase demonstrated a three- to fourfold slowing of both DNA 3'-end-directed and RNA 5'-end-directed RNase H cleavage relative to both wild-type and V179D enzymes, similar to what was observed for P236L in a previously published study (P. Gerondelis et al., J. Virol. 73:5803-5813, 1999). In contrast, the Y181C reverse transcriptase demonstrated a selective acceleration of the secondary RNase H cleavage step during both modes of RNase H cleavage. The relative replication fitness of these mutants in H9 cells was assessed in parallel infections as well as in growth competition experiments. Of the NNRTI-resistant mutants, V179D was more fit than Y181C, and both of these mutants were more fit than V106A, which demonstrated the greatest reduction in RNase H cleavage. These findings, in combination with results from previous work, suggest that abnormalities in RNase H cleavage are a common characteristic of HIV-1 mutants resistant to NNRTIs and that combined reductions in the rates of DNA 3'-end- and RNA 5'-end-directed cleavages are associated with significant reductions in the replication fitness of HIV-1.

Long-term persistence of Coxiella burnetii in the host after primary Q fever

After a primary infection Coxiella burnetii may persist covertly in animals and recrudesce at parturition to be shed in the products of conception and the milk. Similar latent persistence and recrudescence occurs in man: namely, infection of placenta, heart valve or mural endocardium, bone or liver. The numbers of organisms, their viability and cellular form, and the underlying organ sites of latent infection for the coxiella are obscure. During investigations of 29 patients with a chronic sequel to acute Q fever, the post-Q fever fatigue syndrome (QFS) [1-3], sensitive conventional and TaqMan-based PCR revealed low levels of C. burnetii DNA in blood mononuclear cells (5/29; 17%), thin needle liver biopsies (2/14; 14%) and, notably, in bone marrow aspirates (13/20; 65%). Irrespective of the ultimate significance of coxiella persistence for QFS, the detection of C. burnetii genomic DNA in bone marrow several years after a primary infection unveils a new pathological dimension for Q fever.

A role for ectophosphatase in xenobiotic resistance

Xenobiotic resistance in animals, plants, yeast, and bacteria is known to involve ATP binding cassette transporters that efflux invading toxins. We present data from yeast and a higher plant indicating that xenobiotic resistance also involves extracellular ATP degradation. Transgenic upregulation of ecto-ATPase alone confers resistance to organisms that have had no previous exposure to toxins. Similarly, cells that are deficient in extracellular ATPase activity are more sensitive to xenobiotics. On the basis of these and other supporting data, we hypothesize that the hydrolysis of extracellular ATP by phosphatases and ATPases may be necessary for the resistance conferred by P-glycoprotein.

Expression of MMPs and TIMPs in human pterygia and cultured pterygium epithelial cells

PURPOSE

Pterygia are a common, benign, fibrovascular, and infiltrative process of the corneal-conjunctival junction of unknown pathogenesis. Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes active against all components of the extracellular matrix, whose activity is specifically neutralized by tissue inhibitors of MMPs (TIMPs). In the current study the hypothesis was that MMPs and TIMPs may actively participate in the formation and progression of pterygia.

METHODS

In this study, 25 pterygium specimens and 15 normal conjunctival biopsies obtained from subjects undergoing surgery for glaucoma and cataract, were processed for immunohistochemistry or in situ hybridization. Pterygium epithelial cells (PECs) were cultured under serum-free conditions and exposed to proinflammatory cytokines to determine both the mRNA and protein expression profiles of MMPs and TIMPs.

RESULTS

Collagenase-1 and gelatinase A were expressed in all pterygia examined, specifically localized to the epithelium (directly adjacent to collagen type III), with gelatinase B expression exclusively associated with neutrophils. No collagenase-1 or gelatinase A was detected in normal conjunctiva. TIMP-1 and -3 were localized to epithelial cells with additional TIMP-3 immunoreactivity detected in the extracellular matrix, endothelial cells and leukocytes of all diseased tissue. TIMP-3 protein was evident in 4 of 15 normal conjunctiva. Induction of collagenase-1, gelatinase A, and TIMP-1 mRNA and protein was demonstrated in epithelial cells treated with tumor necrosis factor-alpha and interleukin-1alpha, whereas TIMP-3 expression was unaltered.

CONCLUSIONS

This is the first study to document the cellular expression of MMPs and TIMPs in pterygia and cultured human PECs. MMPs and TIMPs may contribute to the inflammation, tissue remodeling, and angiogenesis that characterize pterygia. Understanding the role these proteins play may lead to novel therapies intended to reduce the progressive nature of pterygia.