Improvement of Storage Medium for Cultured Human Retinal Pigment Epithelial Cells Using Factorial Design

Storage of human retinal pigment epithelium (hRPE) can contribute to the advancement of cell-based RPE replacement therapies. The present study aimed to improve the quality of stored hRPE cultures by identifying storage medium additives that, alone or in combination, contribute to enhancing cell viability while preserving morphology and phenotype. hRPE cells were cultured in the presence of the silk protein sericin until pigmentation. Cells were then stored for 10 days in storage medium plus sericin and either one of 46 different additives. Individual effects of each additive on cell viability were assessed using epifluorescence microscopy. Factorial design identified promising additive combinations by extrapolating their individual effects. Supplementing the storage medium with sericin combined with adenosine, L-ascorbic acid and allopurinol resulted in the highest cell viability (98.6 ± 0.5%) after storage for three days, as measured by epifluorescence microscopy. Flow cytometry validated the findings. Proteomics identified 61 upregulated and 65 downregulated proteins in this storage group compared to the unstored control. Transmission electron microscopy demonstrated the presence of melanosomes after storage in the optimized medium. We conclude that the combination of adenosine, L-ascorbic acid, allopurinol and sericin in minimal essential medium preserves RPE pigmentation while maintaining cell viability during storage.

Constrained evolution of a bispecific enzyme: lessons for biocatalyst design

Analysis of the natural evolution of bispecificity in triazine hydrolase highlights the importance of epistasis in protein engineering and evolution.

Effect of activated protein C in second intention healing of equine distal limb wounds: a preliminary study

OBJECTIVE

To investigate the effect of activated protein C (APC) on second intention healing of distal limb wounds in horses.

METHODS

In this experimental study of eight Standardbred geldings, six full-thickness skin wounds (2 × 1.5 cm) were created on one metacarpus (biopsy limb) and five similar wounds were created on the contralateral metacarpus (photographed limb). Three wounds on the biopsy limb were treated topically with 190 µg APC on days 1, 3, 6 and 9, while the remaining three wounds were untreated (control). One treated and one control wound were biopsied on days 4, 7 and 11 for histopathology. Wounds on the photographed limb were treated with either 66% Manuka honey gel, a commercial antibiotic ointment (bacitracin-neomycin-polymixin B ointment; BNP) or petrolatum daily throughout healing, treated on days 1,3,6 and 9 with 190 µg APC or left untreated. These wounds were digitally photographed and the wound area measured on day 1, then weekly until day 49. Overall time to healing was recorded.

RESULTS

There was no effect of APC on wound size, the rate of healing or the overall time to heal. However, compared with control wounds, histological scoring demonstrated enhanced epithelialisation (day 4) and angiogenesis (day 11). Wound healing variables for wounds treated with APC, Manuka honey gel and control wounds were not different and the variables for wounds treated with BNP and petrolatum demonstrated delayed healing.

CONCLUSION

The improvements in histological scores in APC-treated wounds suggest further study into the effect of APC on second intention wound healing in horses is warranted.

Why women consent to surgery, even when they don't want to: a qualitative study

Although there has been critical analysis of how the informed consent process functions in relation to participation in research and particular ethical 'dilemmas', there has been little examination of consenting to more routine medical procedures. We report a qualitative study of 25 women who consented to surgery. Of these, nine were ambivalent or opposed to having an operation. When faced with a consent form, women's accounts suggest that they rarely do anything other than obey professionals' requests for a signature. An interactionist analysis suggests that women's capacity to act is reduced by the hospital structure of tacit, socially-imposed rules of conduct. Bourdieu's concepts of habitus, capital and symbolic power/violence show how the practical logic that women apply confers a 'sense of place' relative to professionals. Women experience deficits in capital that constrain their ability to exercise choice. This work demonstrates the weakness of the consent process as a safeguard of autonomy.

Is 'inconsistency' in research ethics committee decision-making really a problem? An empirical investigation and reflection

Research Ethics Committees (RECs) are frequently a focus of complaints from researchers, but evidence about the operation and decisions of RECs tends to be anecdotal. We conducted a systematic study to identify and compare the ethical issues raised in 54 letters to researchers about the same 18 applications submitted to three RECs over one year. The most common type of ethical trouble identified in REC letters related to informed consent, followed by scientific design and conduct, care and protection of research participants, confidentiality, recruitment and documentation. Community considerations were least frequently raised. There was evidence of variability in the ethical troubles identified and the remedies recommended. This analysis suggests that some principles may be more institutionalized than others, and offers some evidence of inconsistency between RECs. Inconsistency is often treated as evidence of incompetence and caprice, but a more sophisticated understanding of the role of RECs and their functioning is required.

SIRT1, a class III histone deacetylase, regulates TNF-α-induced inflammation in human chondrocytes

OBJECTIVE

The present study was performed to elucidate the possible role of SIRT1 signaling in joint inflammation in human articular chondrocytes.

DESIGN

Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blotting were performed to detect gene products and proteins involved in tumor necrosis factor α (TNF-α)-induced inflammation and cartilage degradation in human primary chondrocytes. Matrix metalloproteinase (MMP)-2 and MMP-9 activity was evaluated by gelatin zymography. Overexpression and knockdown of SIRT1 were also performed to investigate whether SIRT1 is associated with the anti-inflammatory activity of resveratrol in chondrocytes.

RESULTS

Resveratrol dose-dependently inhibited TNF-α-induced cyclooxygenase-2 (COX-2), MMP-1, MMP-3, MMP-13 and PGE(2) production in human chondrocytes. Moreover, MMP-2 and MMP-9 activity was increased by treatment with TNF-α; however, SIRT1 activation decreased the proinflammatory effects induced by TNF-α. In addition, treatment of SIRT1 activator and overexpression of SIRT1 inhibited the expression and activation of the main proinflammatory regulator NF-κB, which was increased by TNF-α. When SIRT1 was overexpressed in chondrocytes, the anti-inflammatory action of SIRT1 was similar to that exerted by resveratrol.

CONCLUSIONS

SIRT1 activation deacetylates and inactivates NF-κB, and thereby, exerts an anti-inflammatory effect on chondrocytes, suggesting that SIRT1 activators could be explored as potential treatments for arthritis.

Enzymatic modification of regenerated cellulosic fabrics to improve bacteria sorption properties

This research investigates the effect of enzymatic treatment of two different regenerated cellulosic fibers (Lyocell and viscose) on their ability of bacteria sorption from an aqueous suspension. The sorption of Escherichia coli (E. coli, Gram negative) and Staphylococcus aureus (S. aureus, Gram positive) cells by treated Lyocell and viscose fabrics were determined by measuring the optical density (OD) of the remaining bacteria suspension after removal of the fabric samples using spectrometry. Fourier transform infrared spectroscopy and scanning electron microscopy (SEM) were utilized to investigate structural and morphological changes of the enzyme treated samples. The result showed that the moisture content and crystallinity of both viscose and Lyocell samples increased after enzymatic treatment. Comparing the results of OD measurements indicated that enzymatic treatment of cellulosic samples significantly increased the bacteria absorption properties compared to those untreated samples. However, treated samples showed different ranges of sorption ability with different kinds of bacteria. The maximum bacteria sorption of 38% and 37% of E. coli bacteria from an aqueous suspension was found for the treated viscose and Lyocell samples compared with only 20% and 10% of the untreated viscose and Lyocell samples, respectively. It was also found that S. aureus sorption of cellulose-treated viscose and Lyocell fabrics from a bacterial suspension could significantly improve up to 33% compared with only 5% of untreated samples. Furthermore, SEM micrographs confirmed that bacterial sorption of the cellulose-treated samples were effectively improved in terms of their uniform sorption on the fibers surface.

The mitochondrial genome and transcriptome of the basal dinoflagellate Hematodinium sp.: character evolution within the highly derived mitochondrial genomes of dinoflagellates

The sister phyla dinoflagellates and apicomplexans inherited a drastically reduced mitochondrial genome (mitochondrial DNA, mtDNA) containing only three protein-coding (cob, cox1, and cox3) genes and two ribosomal RNA (rRNA) genes. In apicomplexans, single copies of these genes are encoded on the smallest known mtDNA chromosome (6 kb). In dinoflagellates, however, the genome has undergone further substantial modifications, including massive genome amplification and recombination resulting in multiple copies of each gene and gene fragments linked in numerous combinations. Furthermore, protein-encoding genes have lost standard stop codons, trans-splicing of messenger RNAs (mRNAs) is required to generate complete cox3 transcripts, and extensive RNA editing recodes most genes. From taxa investigated to date, it is unclear when many of these unusual dinoflagellate mtDNA characters evolved. To address this question, we investigated the mitochondrial genome and transcriptome character states of the deep branching dinoflagellate Hematodinium sp. Genomic data show that like later-branching dinoflagellates Hematodinium sp. also contains an inflated, heavily recombined genome of multicopy genes and gene fragments. Although stop codons are also lacking for cox1 and cob, cox3 still encodes a conventional stop codon. Extensive editing of mRNAs also occurs in Hematodinium sp. The mtDNA of basal dinoflagellate Hematodinium sp. indicates that much of the mtDNA modification in dinoflagellates occurred early in this lineage, including genome amplification and recombination, and decreased use of standard stop codons. Trans-splicing, on the other hand, occurred after Hematodinium sp. diverged. Only RNA editing presents a nonlinear pattern of evolution in dinoflagellates as this process occurs in Hematodinium sp. but is absent in some later-branching taxa indicating that this process was either lost in some lineages or developed more than once during the evolution of the highly unusual dinoflagellate mtDNA.

Expression of bacterial levanase in yeast enables simultaneous saccharification and fermentation of grass juice to bioethanol

This study demonstrates use of recombinant yeast to simultaneously saccharify and ferment grass juice (GJ) to bioethanol. A modified Bacillus subtilis levanase gene (sacC) in which the native bacterial signal sequence was replaced with a yeast α-factor domain, was synthesised with yeast codon preferences and transformed into Saccharomyces cerevisiae (strain AH22) using the expression vector pMA91. AH22:psacC transformants secreted sacCp as an active, hyper-glycosylated (>180 kDa) protein allowing them to utilise inulin (β[2-1] linked fructose) and levan (β[2-6] linkages) as growth substrates. The control (AH22:pMA91) strain, transformed with empty plasmid DNA was not able to utilise inulin or levan. When cultured on untreated GJ levels of growth and bioethanol production were significantly higher in experiments with AH22:psacC than with AH22:pMA91. Bioethanol yields from AH22:psacC grown on GJ (32.7[±4] mg mL(-1)) compared closely to those recently achieved (Martel et al., 2010) using enzymatically pre-hydrolysed GJ (36.8[±4] mg mL(-1)).

Expression, purification and use of the soluble domain of Lactobacillus paracasei beta-fructosidase to optimise production of bioethanol from grass fructans

Microbial inulinases find application in food, pharmaceutical and biofuel industries. Here, a novel Lactobacillus paracasei beta-fructosidase was overexpressed as truncated cytosolic protein ((t)fosEp) in Escherichia coli. Purified (t)fosEp was thermostable (10-50 degrees C) with a pH optimum of 5; it showed highest affinity for bacterial levan (beta[2-6] linked fructose) followed by nystose, chicory inulin, 1-kestose (beta[2-1] linkages) and sucrose (K(m) values of 0.5, 15, 15.6, 49 and 398 mM, respectively). Hydrolysis of polyfructose moieties in agriculturally-sourced grass juice (GJ) with (t)fosEp resulted in the release of >13 mg/ml more bioavailable fructose than was measured in untreated GJ. Bioethanol yields from fermentation experiments with Brewer's yeast and GJ+(t)fosEp were >25% higher than those achieved using untreated GJ feedstock (36.5[+/-4.3] and 28.2[+/-2.7]mg ethanol/ml, respectively). This constitutes the first specific study of the potential to ferment ethanol from grass juice and the utility of a novel core domain of beta-fructosidase from L. paracasei.

African trypanosomiasis in a British soldier

BACKGROUND

Human African trypanosomiasis (sleeping sickness) is a parasitic infection transmitted by day-biting tsetse flies. The diagnostic gold standard is microscopy of blood, lymph node aspirates or CSF. The disease is invariably fatal, if not treated. There are over 300 000 new cases of sleeping sickness each year, and approximately 100,000 deaths.

CASE PRESENTATION

We describe a British soldier who acquired trypanosomiasis in Malawi. He gave no history of a painful insect bite but presented with classical early signs of sleeping sickness (a primary chancre, regional lymphadenopathy, circinate erythema and a cyclical fever pattern). His condition worsened in the next week and trypanosomes were observed in a blood sample. He was aeromedically evacuated to Johannesburg, where Stage One Trypanosoma brucei rhodesiense infection was confirmed; he also had renal and liver failure, pancytopenia and heart block. He was treated with intravenous suramin. He recovered fully over the next 5 months.

RECOMMENDATIONS

Medical officers deploying to eastern and southeastern Africa must be familiar with the common presenting signs and symptoms of T b rhodesiense sleeping sickness, and should have access to a reliable local microscopy service at all times. Confirmed sleeping sickness requires immediate transfer to a tertiary diagnostic and treatment centre, where suramin (for T b rhodesiense infection) or pentamidine (for T b gambiense) and also melarsoprol (for Stage Two disease) must be immediately available.

Referral and attendance at a specialist antenatal clinic: qualitative study of women's views

OBJECTIVE

To explore women's views on being referred to and attending a specialist antenatal hypertension clinic.

DESIGN

Qualitative interview study.

SETTING

A pregnancy hypertension clinic in a large teaching hospital in the East Midlands.

POPULATION

Twenty-one women (aged 18 years and above) attending the pregnancy hypertension clinic for the first time during their current pregnancy.

METHODS

Women who had been referred to and attended a specialist antenatal clinic participated in semi-structured interviews. Data analysis was based on the constant comparative method.

MAIN OUTCOME MEASURES

Women's experiences and perceptions of being referred to and attending a specialist antenatal clinic.

RESULTS

Being referred to the clinic conferred an 'at risk' status on women. Some women welcomed the referral but others experienced it as unsettling. Many were unclear about why they had been identified as being at risk or had difficulties in accepting the legitimacy of the reason for referral. Women were often inadequately informed about why they were referred to the clinic, what they could expect and the benefits of attending the clinic over management in the community. Although attendance at the clinic was cited as a source of reassurance, the reassurance was often made necessary by concern raised by the initial referral.

CONCLUSIONS

Women's accounts suggest that the interface between community and secondary antenatal services needs improvement to minimise possible adverse effects from identifying women as being 'at risk' during pregnancy.

Participating in a trial in a critical situation: a qualitative study in pregnancy

BACKGROUND

Randomised controlled trials of interventions in critical situations are necessary to establish safety and evaluate outcomes. Pregnant women have been identified as a potentially vulnerable population.

OBJECTIVE

To explore women's experiences of being recruited to ORACLE, a randomised controlled trial of antibiotics in pre-term labour.

METHODS

Twenty qualitative interviews were conducted with women who had participated in ORACLE. Analysis was based on the constant comparative method.

RESULTS

Women gave prominence to the socioemotional aspects of their interactions with healthcare professionals in making decisions on trial participation. Comments on the quality of written and spoken information were generally favourable, but women's accounts suggest that the stressful nature of the situation affected their ability to absorb the information. Women generally had poor understanding of trial design and practices. The main motivation for trial participation was the possibility of an improved outcome for the baby. The second and less prominent motivation was the opportunity to help others, but this was conditional on there being no risks associated with trial participation. In judging the risks of participation, women seemed to draw on "common sense" understandings including a perception that antibiotics were risk free.

DISCUSSION

Recruitment to trials in critical situations raises important questions. Future studies should explore how rigorous governance arrangements for trials, particularly in critical situations, can protect participants rather than relying on ideals of informed consent that may be impossible to achieve. Future research should include a focus on interactions between research candidates and professionals involved in recruitment.

Interaction of cocultured decidual endothelial cells and cytotrophoblasts in preeclampsia

Disturbed cell-cell communication between trophoblasts and the maternal endothelium may be responsible for the deficient endovascular invasion seen in preeclampsia. In vitro studies have been hampered by lack of suitable models to directly examine interactions between these cell types. Using a bilayer coculture model, we examined the effect of decidual endothelial cells on matrix metalloproteinase secretion and the migration of cytotrophoblasts from preeclamptic pregnancies. Cells were incubated on semipermeable membranes in 20% or 2% O(2) with or without the tumor promoter phorbol 12-myristate 13-acetate, which activates matrix metalloproteinase-2 and -9 in endothelial cells. Cytotrophoblasts from preeclamptic pregnancies secreted significantly less matrix metalloproteinase-2 and -9 than their normal counterparts. Although decidual endothelial cells downregulated cytotrophoblast migration in normal pregnancy, this was not observed in cocultures with cytotrophoblasts from preeclamptic pregnancies. In addition, cytotrophoblasts from preeclamptic pregnancies altered phorbol myristate acetate-induced activation of endothelial matrix metalloproteinases. Hypoxia increased cytotrophoblast migration when cells were incubated alone but not in coculture with decidual endothelial cells due to increased adhesion between the two cell types. These results suggest dysfunctional interactive regulation of migration and matrix metalloproteinase secretion in preeclampsia that could result in abnormal endovascular trophoblast invasion of the maternal vasculature.

A synthesis of dominant ecological processes in intensive shrimp ponds and adjacent coastal environments in NE Australia

One of the key environmental concerns about shrimp farming is the discharge of waters with high levels of nutrients and suspended solids into adjacent waterways. In this paper we synthesize the results of our multidisciplinary research linking ecological processes in intensive shrimp ponds with their downstream impacts in tidal, mangrove-lined creeks. The incorporation of process measurements and bioindicators, in addition to water quality measurements, improved our understanding of the effect of shrimp farm discharges on the ecological health of the receiving water bodies. Changes in water quality parameters were an oversimplification of the ecological effects of water discharges, and use of key measures including primary production rates, phytoplankton responses to nutrients, community shifts in zooplankton and delta15N ratios in marine plants have the potential to provide more integrated and robust measures. Ultimately, reduction in nutrient discharges is most likely to ensure the future sustainability of the industry.

In vitro migration of cytotrophoblasts through a decidual endothelial cell monolayer: the role of matrix metalloproteinases

Deficient trophoblast invasion is a major feature of pre-eclampsia. In vitro studies suggest that in normal pregnancy, maternal cells may play a role in controlling trophoblast invasion, although the exact nature of the regulatory interactions between these cells is not fully understood. To examine the effect of maternal-placental cell interactions on matrix metalloproteinase (MMP) secretion and endovascular cytotrophoblast migration in normal pregnancy and in pre-eclampsia, we performed co-culture experiments using cytotrophoblasts from normal pregnancies, together with decidual endothelial cells from both normal and preeclamptic pregnancies. Cells were incubated on semi-permeable membranes with or without phorbol 12-myristate 13-acetate (PMA). Results showed that third trimester cytotrophoblasts are migratory under basal conditions and display a different MMP profile from decidual endothelial cells. Co-culture did not damage either cell type and resulted in reduced latent MMP-9 secretion and reduced cytotrophoblast migration. Although PMA upregulated MMPs in decidual endothelial cells, it had no effect on cytotrophoblast MMP secretion. PMA, however, reduced cytotrophoblast migration. Pre-eclamptic decidual endothelial cells showed reduced MMP-1 secretion, but overall were not different in co-culture from normal endothelial cells. This study demonstrates the effectiveness of a bilayer co-culture model to study maternal-foetal cell interactions and provides evidence that maternal cells may contribute to the control of endovascular cytotrophoblast invasion.

Molecular strain typing of Trichophyton rubrum indicates multiple strain involvement in onychomycosis

BACKGROUND

Trichophyton rubrum is an important cause of onychomycosis. Molecular strain typing methods have recently been developed to address questions of epidemiology and source of relapse following treatment.

OBJECTIVES

To determine whether T. rubrum nail infections are caused by one or more strains of this fungus.

METHODS

Nail specimens from 10 patients with onychomycosis due to T. rubrum were cultured and five colonies per culture plate were selected for molecular strain typing. DNA was extracted from these isolates and subjected to a polymerase chain reaction-based typing method that analyses variations in numbers of repetitive elements in the non-transcribed spacer region of the ribosomal RNA gene repeats.

RESULTS

In six of 10 specimens, there were two or more T. rubrum strain types present.

CONCLUSIONS

This preliminary study suggests that in many cases of fungal nail infection by T. rubrum, multiple strains are involved. This has important implications for epidemiological studies and possibly for therapy.

Human endothelial gelatinases and angiogenesis

Endothelial cell invasion is an essential event during angiogenesis (formation of new blood vessels). The process involves the degradation of the basement membrane and the underlying interstitium. The matrix metalloproteinase (MMP) family is considered to be primarily responsible for matrix degradation. Two members of the family, gelatinase A and B play an important role in angiogenesis. This review outlines recent findings on their regulation in human endothelial cells. Latent gelatinase B is secreted from endothelial cells. This enzyme can also accumulate in the cytosol as an active enzyme, free of TIMP-1. In contrast, latent gelatinase A is constitutively secreted from the cells. Unlike other MMPs, gelatinase A activation occurs on the cell membrane and is mediated by MT1-MMP. A number of physiological activators have recently been described. These include thrombin and activated protein C, both of which activate gelatinase A independent of the MT1-MMP pathway. These new findings may lead to therapeutic interventions for the treatment of angiogenic-dependent diseases such as cancer and arthritis.

An old activity in the cytochrome P450 superfamily (CYP51) and a new story of drugs and resistance

Cytochrome P450 51 (CYP51) is sterol 14alpha-demethylase, known also as Erg11p in yeast. First studied in yeast, where it is one of three CYPs in the genome, it has subsequently gained attention as the only CYP found so far in different kingdoms of life. As such it is central to considerations of CYP evolution. Recent use of CYP51-inhibiting antifungal drugs, such as fluconazole, has also been associated with dramatic CYP51 evolution to numerous resistant forms in fungal pathogens. CYP51 has also been discovered in mycobacteria where antifungal azoles have effect and might be of value against tuberculosis. Evolutionary and therapeutic aspects of CYP51 studies are discussed.

Analysis of 2beta-carbomethoxy-3beta-(4-fluorophenyl)-N-(3-iodo-E-allyl)nortropane in rat plasma. II. Pharmacokinetic profile in male and female Sprague-Dawley rats evaluated by capillary electrophoresis

This paper describes a pharmacokinetic study performed in Sprague-Dawley rats after i.v. administration of a single 6-mg/kg dose of 2beta-carbomethoxy-3beta-(4-fluorophenyl)-N-(3-iodo-E-allyl)nortropane (Altropane). Plasma samples were collected from the retro-orbital sinus at times up to 3 h after drug administration, extracted by solid-phase extraction, and the drug levels determined by capillary electrophoresis (CE). Pharmacokinetic parameters were determined by a standard noncompartmental model using WinNonlin version 1.5. The maximum plasma concentrations, clearances of the drug, and areas under the curve for male and female rats were 5.74 and 7.26 microg/ml, 135.7 and 98.5 ml/kg x min, and 44.23 and 60.92 microg x min/ml, respectively. The drug was cleared very rapidly from the systemic circulation, with a terminal t(1/2) of 7 to 10 min and a mean residence time of about 11 min for both sexes. The volume of distribution was approximately 1 l/kg. No metabolites were detected when the samples were analyzed individually. However, after samples were pooled and concentrated, traces of two unknown peaks that may represent metabolites were detected in concentrates from the last two timepoints. Part I of this work [J. Chromatogr. A, 895 (2000) 87] describes validation of CE methods for the analysis of aqueous and plasma samples of Altropane, including its solid-phase extraction from rat plasma.

Molecular identification and strain typing of dermatophyte fungi

The rDNA spacer regions provide easily accessible, polymorphic genetic loci for both species and strain identification of dermatophyte fungi. Nucleotide substitutions and length polymorphisms in the internal transcribed spacers (ITS) can be indexed by sequencing or by PCR restriction endonuclease analysis, and provide a rapid and accurate means of identifying dermatophyte taxa. Multiple sets of tandem repeats that vary in copy number both within and between strains produce length heterogeneity in the nontranscribed spacer (NTS) region. Amplification of these repeats using specific PCR, or their detection by Southern hybridisation with a generic ribosomal DNA probe, provides a sensitive and discriminatory technique for strain identification in T. rubrum and other dermatophyte fungi.

Moderating effect of ear preference on personality in the prediction of sales performance

This study examined the relationship between ear preference, personality, and performance ratings on 203 telesales staff. Social desirability scores were a significant predictor of two relatively independent sets of supervisor ratings (actual performance and developmental potential) in interaction with ear preference. It was found that the social desirability scale was a significant positive predictor for staff preferring a right ear headset, but a negative predictor for staff preferring a left ear headset. These results were interpreted in terms of different strategies used to achieve successful sales.

Strain identification of Trichophyton rubrum by specific amplification of subrepeat elements in the ribosomal DNA nontranscribed spacer

Trichophyton rubrum is the commonest cause of dermatophytosis of skin and nail tissue. Molecular characterization of the T. rubrum ribosomal DNA nontranscribed-spacer region revealed two novel tandemly repetitive subelements (TRSs): TRS-1, containing a 27-bp palindromic sequence, and TRS-2. Specific amplification of TRS-1 produced strain-characteristic banding patterns (PCR types), with 21 TRS-1 PCR types recognized from 101 clinical isolates. Four simple patterns representing 1 to 4 copies of TRS-1 accounted for 75 (75%) of all 101 strains, whereas more complex patterns were observed for 21 (20%) of the 101 isolates. The copy number of TRS-2 was 0 to 3 repeats per cistron, with a majority of isolates having two copies of this element. Eleven isolates were polymorphic for TRS-2, and in combination, 23 separate PCR types were recognized by amplification of both TRS-1 and TRS-2. The PCR patterns from both elements were stable and reproducible. Elements with homology to TRS-1 were present in three phylogenetically related species, Trichophyton violaceum, Trichophyton gourvilii, and Trichophyton soudanense, but these elements were not identified in other dermatophyte taxa. There was no clear correlation of PCR type with specimen (skin or nail tissue), but certain PCR types appeared to show a bias in geographic distribution. This new method of typing T. rubrum will enable important questions about pathogenesis and epidemiology of this fungus to be addressed.

Bactericidal and inhibitory effects of azole antifungal compounds on Mycobacterium smegmatis

Azole antifungals are central to therapy and act by inhibiting a cytochrome P450, sterol 14-demethylase and blocking normal sterol synthesis. Our recent identification of a mycobacterial sterol biosynthetic pathway led us to probe the efficacy of a range of these compounds against Mycobacterium smegmatis. Several showed equivalent or greater inhibitory effects to those against Candida albicans, and bactericidal activity was demonstrated for four compounds, clotrimazole, econazole, miconazole and tebuconazole. The major drug used clinically, fluconazole, was ineffective. The results are discussed in the light of the world-wide spread of tuberculosis, including drug-resistant forms and the requirement for new drugs.

Effect of soy-based breakfast cereal on blood lipids and oxidized low-density lipoprotein

Consumption of soy protein may reduce the risk of cardiovascular disease both through reduction in serum lipids and by the antioxidant properties of protein-associated soy isoflavones. However, the effect that processing required for the manufacture of breakfast cereals may have on the lipid lowering and antioxidant activities of soy has not been studied. We have therefore assessed the health benefits of soy incorporation into breakfast cereals. Twenty-five hyperlipidemic men and women took soy (providing 36 g/d soy protein and 168 mg/d isoflavones) and control breakfast cereals, each for 3 weeks in a randomized crossover study with a 2-week washout period between treatments. Fasting blood samples were obtained pretreatment and at weeks 2 and 3 of each treatment. No significant difference was seen in serum lipids between treatments at week 3 apart from a 3.8% +/- 1.5% higher apolipoprotein A-1 level on control versus soy (P = .021). However, oxidized low-density lipoprotein (LDL) was reduced on the test compared with the control both as total dienes in LDL and as the ratio of conjugated dienes to cholesterol in the LDL fraction by 9.2% +/- 4.3% (P = .042) and 8.7% +/- 4.2% (P = .050), respectively. High isoflavone intakes in soy breakfast cereals may decrease the risk of cardiovascular disease by reducing oxidized LDL, while having no significant effect on the absolute concentration of LDL cholesterol.

Three-dimensional collagen matrices induce delayed but sustained activation of gelatinase A in human endothelial cells via MT1-MMP

Gelatinase A, a member of the matrix metalloproteinase (MMP) family, plays an important role during angiogenesis. It is constitutively expressed by human endothelial cells as a latent enzyme and requires activation. Thrombin is the only described physiological inducer of gelatinase A in human endothelial cells. In this study, we investigated the mechanisms of gelatinase A activation by another physiological inducer, collagen. Endothelial cells were cultured on various ECM components for 24 h and the conditioned media were assessed for gelatinase A activity using gelatin zymography. The results demonstrated that type I collagen matrix specifically activates gelatinase A after 24 h in human umbilical vein and 48 h in neonatal foreskin endothelial cells. In contrast, thrombin activated gelatinase A after only 2 h. Activation by collagen was sustained over long periods of time in culture (96 h). Unlike thrombin-induced activation, collagen required active membrane type 1-MMP (MT1-MMP) on the endothelial cell surface to activate gelatinase A. In addition, collagen-induced activation of gelatinase A was inhibited by antibodies to the integrin receptor, alpha(2)beta(1), but not alpha(3)beta(1). Our findings, that collagen can provide long-term activation of gelatinase A are likely to be relevant to endothelial cell invasion during angiogenesis.

The structure of the Eysenck Personality Profiler

The dominant issue in personality research over the last decade has been concerned with the fundamental structure of personality and the best measures of that structure. Exploratory factor analysis was used to investigate possible three- and five-factor solutions to the Eysenck Personality Profiler (EPP; Eysenck, Barrett, Wilson, & Jackson, 1992) which consists of 21 primary scales categorized under three super-factors. Little evidence was found to support Costa and McCrae's (1995) unequivocal comment that a five-factor solution fitted the data well. Confirmatory factor analysis was also used, by means of structural equation modelling, to estimate the goodness of fit of three- and five-factor models and little evidence was found to favour one solution over the other. A shorter version of the EPP, which consists of just nine scales, seemed to favour a three-factor solution. Various criticisms of the EPP are also made: some scales have relatively low alpha, there seem to be too many neuroticism scales and the three category response scales seem less than ideal.

Effect of soy protein foods on low-density lipoprotein oxidation and ex vivo sex hormone receptor activity--a controlled crossover trial

Plant-derived estrogen analogs (phytoestrogens) may confer significant health advantages including cholesterol reduction, antioxidant activity, and possibly a reduced cancer risk. However, the concern has also been raised that phytoestrogens may be endocrine disrupters and major health hazards. We therefore assessed the effects of soy foods as a rich source of isoflavonoid phytoestrogens on LDL oxidation and sex hormone receptor activity. Thirty-one hyperlipidemic subjects underwent two 1-month low-fat metabolic diets in a randomized crossover study. The major differences between the test and control diets were an increase in soy protein foods (33 g/d soy protein) providing 86 mg isoflavones/2,000 kcal/d and a doubling of the soluble fiber intake. Fasting blood samples were obtained at the start and at weeks 2 and 4, with 24-hour urine collections at the end of each phase. Soy foods increased urinary isoflavone excretion on the test diet versus the control (3.8+/-0.7 v 0.0+/-0.0 mg/d, P < .001). The test diet decreased both oxidized LDL measured as conjugated dienes in the LDL fraction (56+/-3 v 63+/-3 micromol/L, P < .001) and the ratio of conjugated dienes to LDL cholesterol (15.0+/-1.0 v 15.7+/-0.9, P = .032), even in subjects already using vitamin E supplements (400 to 800 mg/d). No significant difference was detected in ex vivo sex hormone activity between urine samples from the test and control periods. In conclusion, consumption of high-isoflavone foods was associated with reduced levels of circulating oxidized LDL even in subjects taking vitamin E, with no evidence of increased urinary estrogenic activity. Soy consumption may reduce cardiovascular disease risk without increasing the risk for hormone-dependent cancers.

Activated protein C directly activates human endothelial gelatinase A

Angiogenesis (formation of new blood vessels) occurs in a number of diseases such as cancer and arthritis. The matrix metalloproteinase (MMP), gelatinase A, is secreted by endothelial cells and plays a vital role during angiogenesis. It is secreted as a latent enzyme and requires extracellular activation. We investigated whether activated protein C (APC), a pivotal molecule involved in the body's natural anti-coagulant system, could activate latent gelatinase A secreted by human umbilical vein endothelial cells (HUVEC). APC induced the fully active form of gelatinase A in a dose (100-300 nM)- and time (4-24 h)-responsive manner. The inactive zymogen, protein C, did not activate gelatinase A when used at similar concentrations. APC did not up-regulate membrane type 1 MMP (MT1-MMP) mRNA in HUVEC. In addition, the MMP inhibitor, 1, 10-phenanthroline (10 nM), was unable to inhibit APC-induced activation. These results suggested that MT1-MMP was not involved in the activation process. APC activation of gelatinase A occurred in the absence of cells, indicating that it acts directly. APC may contribute to the physiological/pathological mechanism of gelatinase A activation, especially during angiogenesis.

Preeclamptic decidual microvascular endothelial cells express lower levels of matrix metalloproteinase-1 than normals

In preeclampsia, invasion of intrauterine decidual blood vessels by placental cytotrophoblasts is significantly reduced. This study examined the secretion of matrix metalloproteinases (MMP) by cultured human decidual endothelial cells from normal (NDEC) and preeclamptic (PEDEC) pregnancies. MMPs secreted into the culture medium were measured using zymography, Western blotting, and ELISA. Results were confirmed by Northern analysis. Phorbol myristate acetate, known to induce protease activity in other endothelial cell populations, stimulated MMP1, MMP9, and TIMP1 secretion in both NDEC and PEDEC. Neither tumor necrosis factor-alpha nor transforming growth factor-beta, both thought to have significant roles in the control of placentation, affected MMP secretion. MMP9 and TIMP1 levels were similar between the two cell types; however, MMP1 secretion was markedly different between the cell types. NDEC expressed higher levels of MMP1 under both basal (160 +/- 32 ng/10(6) cells) and stimulated (275 +/- 50) conditions compared to PEDEC (32 +/- 24 and 70 +/- 53, respectively). The lower MMP1 expression of decidual endothelial cells from preeclamptic women may inhibit endovascular invasion by cytotrophoblasts. These findings may, at least partly, explain the relative failure of trophoblasts to invade maternal decidual blood vessels in preeclamptic pregnancy.

Thrombin rapidly and efficiently activates gelatinase A in human microvascular endothelial cells via a mechanism independent of active MT1 matrix metalloproteinase

Thrombin has been shown previously to activate gelatinase A in human umbilical vein endothelial cells. The activation is thought to be mediated by membrane-type 1 matrix metalloproteinase (MT1-MMP) on the cell surface, which generates the 62-kd intermediate and the 59-kd fully active forms. We used microvascular endothelial cells derived from human neonatal foreskin to investigate the mechanism of gelatinase A activation by thrombin. Gelatinase A was measured using zymography. Whereas activation by PMA generated both the 62-kd intermediate and the 59-kd fully active forms of gelatinase A after 24 hours, activation by thrombin produced only the 59-kd species rapidly (within 2 hours). Four findings indicate that MT1-MMP was not involved in thrombin-induced activation: (1) there was no up-regulation of MT1-MMP after 2 hours stimulation by thrombin, even though there was activation of gelatinase A; (2) the 62-kd intermediate species was never detected in response to thrombin; (3) tissue inhibitor of matrix metalloproteinase-2 completely prevented gelatinase A activation induced by PMA but not by thrombin; and (4) the metalloproteinase inhibitor 1,10-phenanthroline did not inhibit thrombin-induced activation. Together, these data demonstrate that activation of gelatinase A by thrombin is different from PMA and operating via a pathway independent of MT1-MMP. The ability of thrombin to rapidly and efficiently activate gelatinase A is likely to be a major contributing factor to its potent angiogenic activity.

Species identification and strain differentiation of dermatophyte fungi by analysis of ribosomal-DNA intergenic spacer regions

Restriction fragment length polymorphisms (RFLPs) identified in the ribosomal-DNA (rDNA) repeat were used for molecular strain differentiation of the dermatophyte fungus Trichophyton rubrum. The polymorphisms were detected by hybridization of EcoRI-digested T. rubrum genomic DNAs with a probe amplified from the small-subunit (18S) rDNA and adjacent internal transcribed spacer (ITS) regions. The rDNA RFLPs mapped to the nontranscribed spacer (NTS) region of the rDNA repeat and appeared similar to those caused by short repetitive sequences in the intergenic spacers of other fungi. Fourteen individual RFLP patterns (DNA types A to N) were recognized among 50 random clinical isolates of T. rubrum. A majority of strains (19 of 50 [38%]) were characterized by one RFLP pattern (DNA type A), and four types (DNA types A to D) accounted for 78% (39 of 50) of all strains. The remaining types (DNA types E to N) were represented by one or two isolates only. A rapid and simple method was also developed for molecular species identification of dermatophyte fungi. The contiguous ITS and 5.8S rDNA regions were amplified from 17 common dermatophyte species by using the universal primers ITS 1 and ITS 4. Digestion of the amplified ITS products with the restriction endonuclease MvaI produced unique and easily identifiable fragment patterns for a majority of species. However, some closely related taxon pairs, such as T. rubrum-T. soudanense and T. quinkeanum-T. schoenlenii could not be distinguished. We conclude that RFLP analysis of the NTS and ITS intergenic regions of the rDNA repeat is a valuable technique both for molecular strain differentiation of T. rubrum and for species identification of common dermatophyte fungi.

The role of lipogenesis in the development of obesity and diabetes in Israeli sand rats (Psammomys obesus)

Obesity and diabetes in Israeli sand rats, Psammomys obesus, occur with the sequential transition of animals from normal insulin sensitivity to impaired insulin sensitivity, accompanied by increased adiposity, prior to insulin resistance and obesity, in a manner similar to susceptible human populations. The current study was designed to examine the role of de novo lipid synthesis in the development of excessive weight gain in P. obesus. Sand rats were classified at 12 wk of age into three groups: A, normoglycemic normoinsulinemic; B, normoglycemic hyperinsulinemic; C, hyperglycemic hyperinsulinemic, based on glucose and insulin responses in fed sand rats. Body weight, liver weight, white adipose tissue (WAT) mass and food intake were significantly elevated in Group C compared to Group A (P < 0.05). Lipogenic rate was measured by the amount of 3H incorporated into subscapular brown adipose tissue (BAT), epidiymal WAT and liver per hour, from sand rats with and without access to food. No difference in lipogenic rate was found between the groups in BAT, indicating that this tissue is of minor importance in whole body lipogenesis in P. obesus. In the WAT there was a greater lipogenic rate with the development of obesity and hyperinsulinemia (Group B vs. Group A) but no difference in the liver. However, the onset of hyperglycemia (Group C) further stimulated WAT lipogenesis and initiated increased hepatic lipogenesis, both of which contributed to the pre-existing obesity. This study suggests that elevated lipogenesis is not the primary cause of obesity in P. obesus, as lipogenic rate only markedly increases after obesity is already present in hyperglycemic animals.

Associations between heat-stable (O) and heat-labile (HL) serogroup antigens of Campylobacter jejuni: evidence for interstrain relationships within three O/HL serovars

A comparative examination of the heat-stable (O) and heat-labile (HL) serogrouping results for 9,024 sporadic human isolates of Campylobacter jejuni revealed conserved associations between specific O and HL antigens (O/HL serovars). Forty-nine percent of the isolates which grouped for both O and HL antigens belonged to one of three serovars: O 4 complex/HL 1 (17.9%), O 1/HL 2 (16.8%), or O 50/HL 7 (14.5%). Other common serovars were O 2/HL 4 (8.3%), O 6/HL 6 (8.1%), O 53/HL 11 (4.5%), O 19/HL 17 (3.3%), O 5/HL 9 (3.3%), O 9/HL 9 (3.2%), and O 23/HL 5 (3.1%). These 10 serovars accounted for 83.1% of the serogroupable isolates. A large number of strains (41.3%) could be typed by only one of the two methods or could not be serogrouped (11%). Strains belonging to three serovars, O 2/HL 4, O 50/HL 7, and O 23/HL 5, were further characterized by combining data from expressed features (O/HL serogroups, phage groups, and biotypes) with restriction fragment length polymorphism genotypes. These polyphasic data demonstrated that within each serovar, individual isolates showed substantial conservation of both genomic and phenotypic characteristics. The essentially clonal nature of the three serovars confirmed the potential of combined O and HL serogrouping as a practical and phylogenetically valid method for investigating the epidemiology of sporadic C. jejuni infection.

Rheumatoid synovial endothelial cells secrete decreased levels of tissue inhibitor of MMP (TIMP1)

OBJECTIVES

Angiogenesis (the formation of new blood vessels) is a major component of the inflammatory pannus in rheumatoid arthritis (RA). Matrix metalloproteinase (MMP) secretion by microvascular endothelial cells is an essential step in angiogenesis. The secretion of MMP1, MMP2, MMP9, and TIMP1 by human microvascular endothelial cells derived from RA synovium (RASE) to normal synovium (NSE) and neonatal foreskin (FSE) was compared.

METHODS

Confluent monolayers of endothelial cells in basal medium were pre-incubated for 24 hours in the presence or absence of phorbol myristate acetate (PMA, 100 ng/ml). MMP1 activity was measured using a spectrophotometric assay and western blotting. MMP2 and MMP9 were measured using zymography. TIMP1 was measured by enzyme linked immunosorbent assay and western blotting.

RESULTS

There was little difference between the amounts of MMP2 secreted by any of the cell lines. In response to PMA both synovial cell types showed a significantly higher MMP1 and MMP9 activity compared with FSE, although there was no difference between RASE and NSE. Tumour necrosis factor alpha had minimal effect on MMP activity. There was a striking decrease in the amount of TIMP1 secreted by RASE compared with normal synovium.

CONCLUSIONS

As overall MMP activity is a balance between the amount of MMP and TIMP1 present, the low levels of TIMP1 produced by RASE would shift the balance in favour of increased MMP activity by these cells. This is likely to contribute to the angiogenic potential of RASE.

Active and tissue inhibitor of matrix metalloproteinase-free gelatinase B accumulates within human microvascular endothelial vesicles

Human gelatinase B is involved in tissue remodeling and angiogenesis. It is thought to be synthesized and rapidly secreted as an inactive precursor. In this report, we have shown that human endothelial cells accumulate active forms of gelatinase B in the cytosol. Microvascular but not macrovascular endothelial cells dramatically increased the expression of cytosolic gelatinase B in response to phorbol myristate acetate. Western blotting showed that tissue inhibitor of metalloproteinase-1 (TIMP1) was also present in the cytosol. Whereas gelatinase B was complexed with TIMP1 in the conditioned medium, it existed as a free enzyme in the cytosol, suggesting that the formation of gelatinase B and TIMP1 complex occurs after their secretion. Immunogold electron microscopy revealed that gelatinase B was localized in secretory vesicles which were especially prominent in invading pseudopodia. In contrast, TIMP1 was found throughout the cytoplasm but was not present in the gelatinase vesicles. The accumulation of intracellular activated gelatinase B, ready for rapid release, may facilitate the migration of microvascular endothelial cells during angiogenesis.

Human microvascular endothelial cells differ from macrovascular endothelial cells in their expression of matrix metalloproteinases

Matrix metalloproteinase (MMP) secretion by microvascular endothelial cells is an essential first step in the formation of new blood vessels (angiogenesis). Since angiogenesis does not occur in large blood vessels, we investigated whether the secretion of MMPs and tissue inhibitor of MMP (TIMP1) differs between micro- and macro-vascular endothelial cells. We compared the secretion of MMPs and TIMP1 by human endothelial cells derived from neonatal foreskin (FSE) and umbilical vein (HUVE) sources. The cells were incubated for 24 hr in the presence or absence of the angiogenic agents, phorbol myristate acetate (PMA, 100 ng/ml) or tumour necrosis factor-alpha (TNF, 100 ng/ml). The cell supernatants were removed and assayed for MMPs and TIMP1 using a spectrophotometric assay for MMP1, zymography, Western blotting and Northern analysis. When endothelial cells were incubated in basal medium for 24 hr they secreted MMP1, MMP2 and TIMP1 but not MMP9. HUVE secreted substantially higher levels of these proteins compared to FSE. In addition, HUVE secreted two low molecular mass bands representing activated forms of MMP2. These activated forms were not present in supernatants derived from FSE. In response to PMA, both FSE and HUVE increased secretion of MMP1 and TIMP1. However, there was a dramatic difference in level of response by the two cell types with FSE secreting substantially more TIMP1 and MMP9 compared to HUVE. These data clearly show that cultured endothelial cells derived from microvascular vs macrovascular tissues exhibit different MMP and TIMP secretory profiles.

Genotype analysis of human blood isolates of Campylobacter jejuni in England and Wales

Genomic profiles were obtained for 76 strains of Campylobacter jejuni isolated from bacteraemic patients in England and Wales over the period 1981-94. Genotyping was performed by restriction fragment length polymorphism (RFLP) analysis using a random cloned DNA probe, and by ribotyping with a PCR-generated C. jejuni 16S ribosomal DNA probe. Phenotypic characterization was achieved by heat-stable (HS) and heat-labile (HL) serogrouping, and Preston phagetyping and biotyping. The blood isolates were genomically heterogenous, with 24 RFLP/16S profiles occurring within the 76 strains. Forty-four percent of isolates belonged to one of three RFLP/16S genotypes, reflecting the patterns seen in faecal isolates, except that genotypes usually associated with the HS 1 antigen were uncommon. The two most prevalent genotypes, characteristic of HS 2 and HS 4 strains, showed similarity by cluster analysis. Further evidence was seen of associations between phenotypic and genotypic characters within some HS serogroups. Chromosomal profiling by RFLP analysis does not indicate that particular genotypes have a predisposition to invade the bloodstream.

A novel polymerase chain reaction assay for the detection and speciation of thermophilic Campylobacter spp

A novel PCR amplification method is described which is specific for the thermophilic, enteropathogenic species Campylobacter jejuni, Camp. coli and Camp. upsaliensis. Rapid, accurate speciation of amplified strains is possible on the basis of restriction fragment length polymorphisms of PCR products digested with three restriction enzymes, AluI, DdeI and DraI. The sensitivity of detection is 25 cfu in water, and 2 x 10(3) cfu in full cream milk. An epidemiological application of the assay in detecting non-culturable campylobacters from a contaminated potable water supply is described.

The application of genotyping techniques to the epidemiological analysis of Campylobacter jejuni

Campylobacter jejuni serogroup reference strains and collections of sporadic and outbreak-associated isolates were examined for restriction fragment length polymorphisms (RFLPs), using C. jejuni random chromosomal and 16S rRNA gene probes. A collection of 48 Penner (HS) and 14 Lior (HL) serogroup reference strains, plus 10 clinical isolates, generated 35 RFLP and 26 ribotype patterns. In combination the two loci generated 48 distinct genotypes. Both probes were able to differentiate between certain random isolates of the same HS/HL serogroups but greater discrimination was obtained with RFLP than with ribotyping. Genotyping distinguished accurately between related and unrelated strains when applied to several outbreaks. Genotypic analysis of C. jejuni by restriction fragment length polymorphisms is a valuable technique for epidemiological typing. Chromosomal variation detected by the two unlinked probe loci provides some information about the genetic relationship between isolates.

Direct milk excretion of Campylobacter jejuni in a dairy cow causing cases of human enteritis

Consumption of milk contaminated with Campylobacter jejuni has been described as a cause of human enteritis. Although faecal contamination of milk with the organism has frequently been described, direct milk excretion of Campylobacter jejuni into milk has rarely been linked with cases of human infection. We describe the investigations undertaken following the isolation of Campylobacter jejuni from samples of unpasteurized milk prior to retail. Results of epidemiological investigations including typing of Campylobacter jejuni isolates using pyrolysis mass spectrometry, Penner and Lior serotyping, biotyping, phage typing and restriction fragment length polymorphism analysis provided convincing evidence implicating direct milk excretion of Campylobacter jejuni by one asymptomatic dairy cow as the source of the milk contamination and the cause of local cases of human enteritis.

Sulfated polysaccharides are required for collagen-induced vascular tube formation

We have previously shown that soluble type I collagen can induce vascular tube formation when it contacts the apical side of a confluent endothelial monolayer. In this study we have examined which soluble agent(s) are required for collagen-induced tube formation. Human neonatal foreskin microvascular endothelial cells, maintained in basal medium, were preincubated with each test agent for 2 h prior to the addition of solubilised type I collagen (100 micrograms/ml). After 6 h, tube formation was quantitated using image analysis and expressed as the mean area of tube formation (mm2) per microscopic field of view. Collagen-induced tube formation did not occur in the presence of endothelial cells growth supplement, basic fibroblast growth factor, or normal pooled human serum. In contrast, the addition of heparin at 5 or 50 micrograms/ml caused extensive tube formation (0.22 +/- 0.07 and 0.30 +/- 0.12 mm2, respectively) whereas at 500 micrograms/ml little tube formation occurred (0.03 +/- 0.02 mm2). Protamine sulfate, an antagonist of heparin, inhibited collagen-induced tube formation in a dose-dependent manner. Pentosan polysulfate, dextran sulfate, heparan sulfate, and chondroitin sulfate mimicked the action of heparin. Partially sulfated heparin (de-N-sulfated heparin) stimulated less tube formation compared to heparin (0.15 +/- 0.06 mm2 at 50 micrograms/ml). The nonsulfated polysaccharides, xylan and dextran, had no effect on tube formation. In summary, sulfated polysaccharides are required for collagen-induced vascular tube formation in vitro. The sulfation of these molecules appears to be vital for collagen-induced tube formation.

VLA-2 mediates the interaction of collagen with endothelium during in vitro vascular tube formation

A confluent endothelial monolayer can be induced to form vascular tubes in response to collagen. We investigated possible mechanisms of collagen-induced tube formation by using antibodies to the VLA-2 integrin receptor and protein kinase C inhibitors. Pre-incubation of cells with anti-VLA-2 (which recognises both the alpha 2 and beta 1 chains) and AK7 (which recognises only the alpha 2 chain) showed a dose-dependent inhibition of tube formation. At 50 micrograms/ml, anti-VLA-2 completely inhibited collagen-induced tube formation, whereas AK7 caused only partial inhibition. Both chlorpromazine and trifluoperazine, at concentrations of 10 microM, prevented tube formation (> 40% inhibition). In summary, the VLA-2 integrin receptor plays a role in the induction of tube formation by type I collagen. Protein kinase C may be activated during this process.