Using intervention mapping to develop an intervention for multiparty communication with people with congenital deafblindness

BACKGROUND

Due to their dual sensory impairment, people with congenital deafblindness (CDB) are rarely naturally involved in other people's conversations. Their communication partners find it challenging to include them in group conversations. However, overhearing others communicate is important for developing social and communication skills. Hence, we developed an intervention program to guide communication partners in offering multiparty communication to people with CDB. This article describes how the program was developed through an intervention mapping approach.

METHOD

Intervention mapping is a six-step process: logic model, model of change, program design, program production, program implementation plan, and evaluation plan. These six steps were applied to systematically develop a program to foster multiparty communication in people with CDB. Representatives of the involved groups participated in the project group and the working group to ensure feasibility and acceptability.

RESULTS

Following the intervention mapping steps resulted in creation of a program for communication partners that consists of an education session, practicals, and four video-feedback sessions. Information sessions for practitioners and managers were also developed. The program was implemented incrementally with program implementers in each organization. A subjective evaluation and an impact evaluation were done after each implementation phase.

DISCUSSION

Intervention mapping was used to develop a program that connects theory to practice. The program appeared to meet the communication partners' needs and be feasible in terms of time investment. This article offers suggestions for broadening the scope of the program to other settings and for further investigating the effects of the program on the social and communication skills of people with CDB.

Development of an adverse outcome pathway network for nephrotoxicity

Adverse outcome pathways (AOPs) were introduced in modern toxicology to provide evidence-based representations of the events and processes involved in the progression of toxicological effects across varying levels of the biological organisation to better facilitate the safety assessment of chemicals. AOPs offer an opportunity to address knowledge gaps and help to identify novel therapeutic targets. They also aid in the selection and development of existing and new in vitro and in silico test methods for hazard identification and risk assessment of chemical compounds. However, many toxicological processes are too intricate to be captured in a single, linear AOP. As a result, AOP networks have been developed to aid in the comprehension and placement of associated events underlying the emergence of related forms of toxicity-where complex exposure scenarios and interactions may influence the ultimate adverse outcome. This study utilised established criteria to develop an AOP network that connects thirteen individual AOPs associated with nephrotoxicity (as sourced from the AOP-Wiki) to identify several key events (KEs) linked to various adverse outcomes, including kidney failure and chronic kidney disease. Analysis of the modelled AOP network and its topological features determined mitochondrial dysfunction, oxidative stress, and tubular necrosis to be the most connected and central KEs. These KEs can provide a logical foundation for guiding the selection and creation of in vitro assays and in silico tools to substitute for animal-based in vivo experiments in the prediction and assessment of chemical-induced nephrotoxicity in human health.

Communication development from an intersubjective perspective: Exploring the use of a layered communication model to describe communication development in students with congenital deafblindness

This exploratory study conducts a quantitative investigation on the communication development of students with congenital deafblindness (CDB). First, a layered communication model (LCM) is introduced, describing communicative behaviors based on three layers of intersubjective development for typically developing children (Bråten & Trevarthen, 2007). Subsequently, an analysis is made of how applicable the LCM is for children with CDB. Video recordings of four dyads of students with CDB with varying developmental ages and their teachers are coded using ten-second partial interval coding. The presence of LCM behaviors, the student and teacher contributions to communication, and the development over a half-year period are described and compared between dyads. The results reflected the developmental differences between dyads. At the primary layer, all behaviors occurred a comparable number of times between dyads, which confirms that this is a basic communication layer. Quantitative differences between dyads were encountered between and within the secondary and tertiary layers. Teacher contribution was higher for students with lower developmental ages compared to students with higher developmental ages. Also, teacher contribution was higher for the secondary and tertiary layer behaviors of the LCM compared to the primary layer behaviors. No increase was found in the behaviors over the half-year period. Results suggest that the LCM can be used to gain insight into the communication level of a dyad, hereby paving the way for intervention studies to improve communication development.

Toward a Diagnostic Intervention Model for Fostering Harmonious Interactions between Deaf-Blind Children and Their Educators

This article presents a diagnostic intervention model as a guide for designing and conducting interventions to foster harmonious interactions between deaf-blind children and their educators in various settings and explicates its theoretical and empirical foundations.

Contact: Effects of an Intervention Program to Foster Harmonious Interactions between Deaf-Blind Children and Their Educators

This study examined the effects of an intervention program to improve the quality of daily interaction between six congenitally deaf-blind children and their 14 educators (teachers, caregivers, and mothers). With video analysis as the most important tool, the interaction coaches trained the educators to recognize the children's signals and attune their behaviors to the children's.

Applying the Diagnostic Intervention Model for Fostering Harmonious Interactions between Deaf-Blind Children and their Educators: A Case Study

This article demonstrates the use of the Diagnostic Intervention Model in everyday practice and the effects of its application in a case study of Kris and his educator using individual coaching. The implications of the case for everyday practice are discussed.

Fostering Harmonious Interactions in a Boy with Congenital Deaf-Blindness: A Single-Case Study

This article demonstrates the effectiveness of applying the Diagnostic Intervention Model for fostering harmonious interactions by describing a single-case study. Changes in the caregiver's turn-giving had substantial effects on the child's turn-taking, regulation of intensity, and approving and disapproving answers. The interaction effects were less clear for the child's initiatives.

Team Interaction Coaching with Educators of Adolescents who are Deaf-Blind: Applying the Diagnostic Intervention Model

In an earlier publication, we presented the Diagnostic Intervention Model, which can be used as a guide in the design and conduct of interventions to foster harmonious interactions between children who are deaf-blind and their educators. This article demonstrates the use of the model in everyday practice and the effects of its application in two case studies, using team interaction coaching. Implications for everyday practice are discussed.

Interaction Coaching with Mothers of Children with Congenital Deaf-Blindness at Home: Applying the Diagnostic Intervention Model

This article describes the application of the Diagnostic Intervention Model and its effects in two case studies of 3-year-old boys, Rolf and Ruud, using individual interaction coaching with their mothers. Positive effects were found for all the target categories in both cases, although an interaction that used materials appeared to be more complex.

Scaffolding the Communication of People With Congenital Deafblindness: An Analysis of Sequential Interaction Patterns

The High Quality Communication intervention aims to stimulate interpersonal communication between individuals with congenital deaf-blindness (CDB) and their social partners. Found effective in multiple-case experiments, the intervention is based on Trevarthen's theory of inter-subjective development (Bråten & Trevarthen, 2007), which describes children's innate and developing ability to share subjective states in interpersonal communication and social partners' mediating role in this development. One implication of this theory is that social partners can support the emergence of higher-complexity communication behaviors in individuals who are still developing these behaviors. To test this proposition, communication patterns between individuals with CDB and their parents, teachers, and professional caregivers were analyzed. Analysis of two-event sequences of communicative behaviors showed a highly significant correspondence between the behavior of the social partner and the subsequent behavior of the individual with CDB, confirming that social partners can scaffold higher-complexity communication within interpersonal communication.

Fostering Emotion Expression and Affective Involvement with Communication Partners in People with Congenital Deafblindness and Intellectual Disabilities

BACKGROUND

Recent studies have shown that it is possible to foster affective involvement between people with congenital deafblindness and their communication partners. Affective involvement is crucial for well-being, and it is important to know whether it can also be fostered with people who have congenital deafblindness and intellectual disabilities.

METHODS

This study used a multiple-baseline design to examine whether an intervention based on the Intervention Model for Affective Involvement would (i) increase affective involvement between four participants with congenital deafblindness and intellectual disabilities and their 13 communication partners and (ii) increase the participants' positive emotions and decrease their negative emotions.

RESULTS

In all cases, dyadic affective involvement increased, the participants' very positive emotions also increased and the participants' negative emotions decreased.

CONCLUSION

The results indicate that communication partners of persons with congenital deafblindness and intellectual disabilities can be successfully trained to foster affective involvement.

Effects of changes in life circumstances on interaction and communication in adults with congenital deafblindness and an intellectual disability

This study examined the effects of the first 2 years of the ongoing Project CHANGE, aimed at improving interaction and communication in adults with congenital deafblindness (CDB) and an intellectual disability (ID). Six adults with no history of deafblind education participated in this study. These first 2 years of CHANGE involved an improvement in living conditions, including a transition to a new group home and interactions with specialized caregivers. Video recordings and file information were used to measure interaction and communication during baseline (T0) and two subsequent periods (T1 and T2). The results show an improvement in interaction: attention by the caregiver, confirmation by the caregiver, and affective involvement all improved. An improvement was also shown in the participants’ level of expressive communication and in the variety of their communicative behaviors. The improvements over time emphasize the need for a specific approach for persons with CDB and an ID.

Applying the Intervention Model for Fostering Affective Involvement with Persons who Are Congenitally Deafblind: An Effect Study

Introduction

In this study, we applied the Intervention Model for Affective Involvement (IMAI) to four participants who are congenitally deafblind and their 16 communication partners in 3 different settings (school, a daytime activities center, and a group home). We examined whether the intervention increased affective involvement between the participants and their communication partners and whether it increased positive emotions and reduced negative emotions in the participants.

Methods

We used video observations in a multiple-baseline design across subjects to assess the effects of the 20-week intervention on the communication partners’ interactions with the participants.

Results

After onset of the intervention, affective involvement increased for three participants, while all four participants showed an increase in positive emotions and a decrease in negative emotions. During follow-up, the positive effect on the participants’ behaviors decreased in most cases, but remained visible as compared to the baseline level.

Discussion

The findings demonstrate that the IMAI can be successfully applied to persons who are congenitally deafblind. Given the small number of participants, replication of the intervention is recommended.

Implications for practitioners

Affective involvement can be increased by training, but it is difficult to maintain this effect over time. Coaching of communication partners on a more permanent basis is recommended to maintain the sharing of emotions between persons who are congenitally deafblind and their communication partners.

Stimulating intersubjective communication in an adult with deafblindness: a single-case experiment

Sensory disabilities may limit a person's development of intersubjectivity, that is, the awareness of self and other, which develops in conjunction with interpersonal communication. This study used intersubjectivity theory to test a new intervention called the High-Quality Communication (HQC) intervention for its effects on a young adult with congenital deafblindness and a developmental age of between 1.5 and 4 years. Three of his social partners were trained to support attunement and meaning making with him through education and video feedback. This study measured seven observation categories at three layers of intersubjective development during a baseline and two intervention phases: dyadic interaction, shared emotion, referential communication, meaning negotiation, shared meaning, declarative communication, and shared past experience. The participant's use of conventional communication was included as an additional category. Effects were observed in all observation categories from the baseline to the intervention phases. Further study of the effectiveness of the HQC intervention is recommended to test whether effects generalize across people and settings.

Measuring sustained interaction in adults with deafblindness and multiple disabilities: Development of an observational coding system

Sustained interaction with other people is of crucial importance for persons with deafblindness and multiple disabilities. This article introduces a relatively time-efficient observational coding system to measure sustained interaction directly from video recordings using only two observation categories: turns and interaction breakdowns. Sustained interaction is defined as a sequence of at least three turns between two interaction partners. An interaction breakdown means that a sequence is not being continued, but is broken off by one of the partners. This article also presents the results of a first study applying the coding system to videos of five adults with deafblindness and multiple disabilities and their caregivers. The system seems well applicable and provides supporting evidence regarding inter-observer reliability. The system can stimulate further research and intervention to increase sustained interaction.

Effects of video-feedback interaction training for professional caregivers of children and adults with visual and intellectual disabilities

BACKGROUND

Individuals in group homes may experience poor quality of social interaction with their professional caregivers, limiting their quality of life. The video-based Contact programme may help caregivers to improve their interaction with clients.

METHOD

Seventy-two caregivers of 12 individuals with visual and intellectual disabilities received a training programme and four individual video-feedback sessions. Quality of interaction was independently measured in an AB-design across subjects with two baseline and three intervention observations, using a time sampling coding system for interactive behaviour as well as a rating for affective mutuality.

RESULTS

From baseline to intervention, significant increases were found for the frequency with which caregivers confirmed the signals of clients, for the proportion of initiatives taken by clients that were responded to by the caregivers, and the affective mutuality as a quality of the interaction. No significant increase in client responsiveness was observed. Caregivers evaluated the intervention as useful and feasible.

CONCLUSIONS

The start of the Contact programme coincided with improved quality of interaction between professional caregivers and clients with visual and intellectual disabilities in group homes. Further research is necessary regarding the generalisability, long-term effects and effects on quality of life.

Describing dialogue between persons with profound intellectual and multiple disabilities and direct support staff using the Scale for Dialogical Meaning Making

BACKGROUND

The dialogical approach of meaning making forms a rich and renewing theoretical perspective to study communication between presymbolic communicators and their interaction partners. The aim of this study is to investigate whether an observation scale based on the dialogical theory, the Scale for Dialogical Meaning Making (S-DMM), has potential to describe these communicative interactions.

METHODS

Eighteen videotaped observations of persons with profound intellectual and multiple disabilities and their support staff were coded using the S-DMM and a consensus-rating procedure.

RESULTS

Sufficient inter-rater agreement and an acceptable range in scores confirm the usefulness of the S-DMM. Strong sub-scale intercorrelations were identified. The quantitative scores and the qualitative arguments supporting the ratings, demonstrate how the S-DMM aids to significantly describe staff-client dialogue.

CONCLUSIONS

Using the S-DMM to describe dialogue with persons with profound intellectual and multiple disabilities appears to be promising. The value of the S-DMM and its consensus-rating procedure are reflected upon and discussed with regard to implications for research and practice.

A fluorescent receptor assay for benzodiazepines using coumarin-labeled desethylflumazenil as ligand

This article describes a novel nonisotopic receptor assay for benzodiazepines with fluorescence detection. As labeled ligand (coumarin-labeled desethylflumazenil, CLDEF), a metabolite of the benzodiazepine antagonist flumazenil (desetheylflumazenil, Ro15-3890) has been coupled to a coumarin fluorophore, via a spacer. CLDEF had a Ki of 6.5 nM. To avoid the interference of the background fluorescence of the receptors in the measurement step, the bound CLDEF was dissociated from the receptors after the filtration step. This dissociation was achieved by incubating the CLDEF-bound to the receptors on the filters-with a weakly acetate buffer. The second filtrates then contained the previously bound CLDEF, which was then quantitated with a RP-HPLC system with a fluorescence detector. The results with a fluorescent receptor assay were very similar to those with a radioreceptor assay, in that the IC50 values of lorazepam were 7.2 +/- 0.5 and 6.6 +/- 0.7 nM, respectively.

A systematic comparison of triple therapies for treatment of Helicobacter pylori infection with proton pump inhibitor/ ranitidine bismuth citrate plus clarithromycin and either amoxicillin or a nitroimidazole

BACKGROUND

Triple therapies with proton pump inhibitor/ranitidine bismuth citrate (RBC), clarithromycin (C) and either amoxicillin (A) or a nitroimidazole (I) are widely accepted as treatment for Helicobacter pylori infection. However, it is not clear which of these antibiotic combinations should be preferred.

AIM

To evaluate whether there is a difference in efficacy between triple therapies with proton pump inhibitor/RBC, clarithromycin and either amoxicillin or a nitroimidazole.

METHODS

The literature was examined for randomized trials comparing proton pump inhibitor/RBC-C-A and proton pump inhibitor/RBC-C-I. Studies were grouped according to the type of acid inhibitor used (proton pump inhibitor or RBC) and differences between pooled cure rates were calculated.

RESULTS

Forty-seven studies were identified: seven using RBC, 39 using proton pump inhibitor, one using both. RBC-C-I was somewhat superior to RBC-C-A, although this difference only reached statistical significance in intention-to-treat analysis. Overall, proton pump inhibitor-C-I and proton pump inhibitor-C-A were equally effective, but in nitroimidazole-susceptible strains, proton pump inhibitor-C-I performed better, in nitroimidazole-resistant strains, proton pump inhibitor-C-A performed better. No serious side-effects were reported and pooled drop-out rates were equal.

CONCLUSIONS

In general, proton pump inhibitor-C-I and proton pump inhibitor-C-A are equally effective and therefore other factors such as local prevalence of resistant strains, cost of therapy and options for second-line treatment should determine which regimen should be preferred. When using RBC, the RBC-C-I combination is somewhat superior to RBC-C-A.

Bactericidal properties of group IIA and group V phospholipases A2

Group V phospholipase A(2) (PLA(2)) is a recently characterized 14-kDa secretory PLA(2) of mammalian heart and macrophage-derived cells. Group IIA PLA(2), which is structurally close to group V PLA(2), has been shown to kill Gram-positive bacteria in vitro and to prevent symptoms of Gram-positive infection in vivo. We studied the antibacterial properties of fully active recombinant rat group IIA and V PLA(2)s. Both group IIA and V PLA(2)s were highly bactericidal against Gram-positive bacteria, including methicillin-resistant staphylococci and vancomycin-resistant enterococci. Only high concentrations of group IIA PLA(2) showed some bactericidal effect against the Gram-negative bacterium Escherichia coli. Our results confirm that group IIA PLA(2) is a potent antibacterial enzyme against Gram-positive bacteria. Moreover, we show here that group V PLA(2) is a novel antibacterial mammalian protein, but is less potent than group IIA PLA(2). Both enzymes may be considered as future therapeutic agents against bacterial infections.

Control of the chemical step by leucine-31 of pancreatic phospholipase A2

A well-defined region of pancreatic and other secreted phospholipase A2 (PLA2), which we call the i-face, makes a molecular contact with the interface to facilitate and control the events and processivity of the interfacial catalytic turnover cycles. The structural features of the i-face and its allosteric relationship to the active site remain to be identified. As a part of the calcium binding (26-34) loop, Leu-31 is located on the surface near the substrate binding slot of PLA2. Analysis of the primary rate and equilibrium parameters of the Leu-31 substitution mutants of the pig pancreatic PLA2 shows that the only significant effect of the substitution is to impair the chemical step at the zwitterionic interface in the presence of added NaCl, and only a modest effect is seen on kcat at the anionic interface. Leu-31 substitutions have little effect on the binding of the enzyme to the interface; the affinity for certain substrate mimics is modestly influenced in W3F, L31W double mutant. The fluorescence emission results with the double mutant show that the microenvironment of Trp-31 is qualitatively different at the zwitterionic versus anionic interfaces. At both of the interfaces Trp-31 is not shielded from the bulk aqueous environment as it remains readily accessible to acrylamide and water. The NaCl-induced change in the Trp-31 emission spectrum of the double mutant on the zwitterionic interface is similar to that seen on the binding to the anionic interface. Together, the kinetic and spectroscopic results show that the form of PLA2 at the zwitterionic interface (Ez) is distinguishably different from the catalytically more efficient form at the anionic interface (Ea). This finding provides a structural basis for the two-state model for kcat activation by the anionic interface. In conjunction with earlier results we suggest that neutralization of certain cationic residues of PLA2 exerts a control on the calcium loop through residue 31.

The phosphatidylcholine to phosphatidylethanolamine ratio of Saccharomyces cerevisiae varies with the growth phase

This study compares the effect of the growth phase on the phospholipid composition and the activity of several phospholipid biosynthetic enzymes in a wild-type yeast grown in fermentable (glucose) and non-fermentable (lactate) semi-synthetic and complete synthetic media. Several distinct differences as well as similarities were found. The cellular phosphatidylcholine: phosphatidylethanolamine (PC:PE) ratio was found to vary with the growth phase, with increases in PC levels at the expense of PE during the transition to stationary phase. The variation was most pronounced in semi-synthetic lactate medium, which is routinely used for the isolation of mitochondria, where the PC:PE ratio changed from 0.9 to 2.2 during this transition. Similar growth phase-dependent changes in PC and PE content were observed in isolated organelles such as mitochondria, mitochondria-associated membranes and microsomes. Phosphatidylinositol (PI) levels were much higher in cells grown on lactate compared to cells grown on glucose (20% vs. 5-10%). Irrespective of the medium, PI levels increased upon entering stationary phase. The activities of the phospholipid biosynthetic enzymes phosphatidylserine synthase and the phospholipid-N-methyltransferases were found to be maximal at the end of logarithmic growth and to decrease upon entering stationary phase in all media. Cells grown on lactate displayed a significantly higher phospholipid:protein ratio than cells grown on glucose. The results are discussed in terms of regulation of phospholipid biosynthesis and membrane biogenesis in response to growth phase and carbon source.

Regulation of the expression of group IIA and group V secretory phospholipases A(2) in rat mesangial cells

Rat mesangial cells synthesize and secrete a secretory phospholipase A(2) upon stimulation of the cells with cytokines, like IL-1beta and TNF and with cAMP elevating agents like forskolin. This enzyme was previously characterized to belong to group IIA sPLA(2). The discovery of several other low molecular weight phospholipases, like group IIC in murine testis and group V in human and rat heart, prompted investigations on the presence of group IIC and group V sPLA(2) in rat mesangial cells. This was done by isolating the RNA from stimulated cells and performing RT-PCR, using primers specific for group IIC and V sPLA(2). The results indicate that rat mesangial cells upon stimulation express next to group IIA also group V sPLA(2). No indications were obtained for the expression of group IIC sPLA(2). The regulation of the expression of group V sPLA(2) at the mRNA level was further investigated by examining the time-dependent expression, the influence of dexamethasone and the signaling route of the IL-1beta stimulation. The results show that the IL-1beta induced expression of group V sPLA(2) mRNA was time dependent and, similar to that of group IIA sPLA(2) mRNA, involves activation of NF-kappaB. However, in contrast to the group IIA sPLA(2), the expression of group V sPLA(2) was not influenced by the presence of dexamethasone. The expression of both phospholipases was also examined at the protein level in stimulated mesangial cells. Western blot analysis shows that stimulated mesangial cells synthesize both group IIA and group V sPLA(2) protein but the expression of group V is lower compared to that of group IIA sPLA(2). In addition, the extent of secretion into the medium appears to be considerably higher for group IIA than for group V sPLA(2).

Fluorescent-labeled ligands for the benzodiazepine receptor. Part 2: The choice of an optimal fluorescent-labeled ligand for benzodiazepine receptor assays

In this article, the binding affinities of the fluorescent-labeled benzodiazepines described in Part 1 are compared to assess the influence of the labeling position and the choice of fluorophore on the binding affinity. This comparison was extended by taking into account the data of other fluorescent-labeled benzodiazepines in the literature. The differences in the binding affinities observed could partly be explained by structure-activity relationships (SAR). On the basis of this comparison, fluorescent-labeled desethylflumazenil (Ro15-3890, 19) derivatives were selected as the most suitable labeled ligands in fluorescent receptor assays. A methyl-methoxycoumarin derivative (Mmc-O-CO-(CH2)3-Ro15-3890) (20b) had a Ki-value of 6.5 nM, and a 7-nitrobenz-2-oxa-1,3diazole derivative (NBD-NH-(CH2)3-Ro15-3890, 21) had a Ki-value of 5.7 nM. In order to yield sufficient sensitivity in the final receptor assay, a suitable fluorescent labeled ligand should have a Ki < 10 nM. A further advantage of the above two ligands is that the benzodiazepine moiety has no receptor affinity of its own. Thus, if some hydrolysis of the labeled ligand were to occur, the resulting Ro15-3890 (18) would hardly affect the outcome of the assay. In the second part of this paper the prerequisites of the fluorophore are being examined. In this regard, 20b is preferred, because the coumarin derivative has higher fluorescence intensities in aqueous media than the NBD-derivative. Therefore, 20b was selected as a fluorescent-labeled ligand in the development of a non-radioactive receptor assay for benzodiazepines.

Fluorescent-labeled ligands for the benzodiazepine receptor. Part 1: Synthesis and characterization of fluorescent-labeled benzodiazepines

Because radioactive labeled ligands in receptor assays have several disadvantages, we synthesized a number of fluorescent-labeled benzodiazepines. Several fluorophores were attached at different positions of 1,4-benzodiazepine molecules in order to assess the impact of the fluorophores and their coupling position on the affinity for the benzodiazepine receptor. Besides the 1,4-benzodiazepines, the 1,2-annelated 1,4-benzodiazepines were also used for labeling. A metabolite of flumazenil (18), desethylflumazenil (Ro15-3890, 19), was labeled with the fluorophore 4-bromomethyl-7-methoxycoumarin, with and without the incorporation of a spacer chain, yielding the methyl-methoxycoumarin (Mmc) derivatives Mmc-Ro15-3890 (20a) and Mmc-O-CO-(CH2)3-Ro15-3890 (20b), respectively. After the synthesis, the fluorescent-labeled benzodiazepines were purified by HPLC, using an analytical RP-C18 column. For the purification of 20b, the chromatographic system was optimized, using multi-criteria decision making (MCDM) techniques. The binding affinities for the benzodiazepine receptor and the fluorescence characteristics were determined for the resulting products.

Transbilayer movement of phosphatidylcholine in the mitochondrial outer membrane of Saccharomyces cerevisiae is rapid and bidirectional

The process of transmembrane movement of phosphatidylcholine (PC) across the outer membrane of mitochondria was investigated in vitro in mitochondrial outer membrane vesicles (OMV) from the yeast Saccharomyces cerevisiae. Phosphatidylcholine-transfer protein (PC-TP) was used to extract radiolabeled PC from OMV, with small unilamellar vesicles serving as acceptor system. Endogenously radiolabeled PC synthesized either via the CDP-choline pathway or via methylation of phosphatidylethanolamine can be extracted completely from the OMV with a t(1/2) of 1 min or less at 30 degrees C. The size of the pool of PC in OMV available for exchange by PC-TP is not affected by pretreatment of the OMV with proteinase K or sulfhydryl reagents. In the reverse experiment where radiolabeled PC was introduced into the OMV, similar characteristics for the exchange were found. The accessibility of labeled PC to externally added phospholipase A(2) was used as a measure for its transmembrane distribution. It was found that PC is not exclusively located in the outer leaflet of the OMV. Only 30-35% can be degraded in intact OMV by phospholipase A(2), irrespective of whether the PC is introduced by PC-TP or endogenously synthesized via either of the pathways of biosynthesis. The results demonstrate the occurrence of rapid bidirectional transbilayer movement of both endogenous and in vitro introduced PC in OMV. Furthermore, there appears to be no preference for mitochondrial import of PC synthesized by either of the pathways in vivo.

Improved benzodiazepine radioreceptor assay using the MultiScreen Assay System

In this article, an improved benzodiazepine radioreceptor assay is described, which allows substantial reduction in assay time. The filtration in this method was performed by using the MultiScreen Assay System. The latter consists of a 96-well plate with glass fibre filters sealed at the bottom, which allows both the incubation and the filtration of the specimen in the same plate. After the filtration, the filters were punched out for quantitation of the bound labeled ligand [3H]flunitrazepam. The results obtained with the MultiScreen Assay System did not differ significantly from the data obtained with the conventional filtration manifold (48S): The Ki's of lorazepam were 2.4 +/- 0.30 and 1.9 +/- 0.15 nM, respectively. In case a radioactive label is replaced by a fluorescent label, the bound labeled-ligand usually cannot be determined in the presence of the receptor material. Here, the bound labeled-ligand has to be dissociated after the filtration step. To dissociate the ligand-receptor complex, Tris- HCl buffer, containing 10 microM flumazenil, was added to the filters and the second filtrates were collected containing the previously bound fractions in the absence of receptor material. This approach showed the same Ki for lorazepam, 2.5 +/- 0.04 nM as without dissociation, when using the radio-labeled benzodiazepine [3H]flunitrazepam.

Enzymatic properties of rat group IIA and V phospholipases A(2) compared

Group IIA and V phospholipases A(2) (PLA(2)s) are known to play a role in inflammatory responses. We have constructed a bacterial expression vector for rat group IIA and V PLA(2)s, over-expressed, folded and purified the proteins with the aim to study and compare the properties of the enzymes in detail. For zwitterionic phospholipid micelles, both enzymes display optimum activity at pH 8. 0 and absolutely require Ca(2+) for enzymatic activity. In the presence of substrate, group V PLA(2) has a high affinity for Ca(2+) (K(Ca2+)=90 microM) while K(Ca2+) of group IIA PLA(2) was found to be 1.6 mM. The absence of substrate only marginally influences the Ca(2+) affinities. In contrast to group IIA PLA(2), group V PLA(2) does not show a jump in the activity profile at substrate concentrations around the critical micelle concentration. Direct binding studies using n-alkylphosphocholines indicate that group V PLA(2) forms protein-lipid aggregates at pre-micellar lipid concentrations in a cooperative and Ca(2+)-dependent manner. This behavior, which is comparable to that observed for the PLA(2) from Naja melanoleuca snake venom, reflects the high affinity of this enzyme for zwitterionic phospholipids. Competitive inhibition by the substrate analogues (R)-2-dodecanoylaminohexanol-1-phosphocholine and its phosphoglycol derivative was tested on zwitterionic micelles as substrate. Group IIA PLA(2) shows a preference for the phosphoglycol inhibitor whereas the phosphocholine inhibitor binds stronger to the active site of group V PLA(2). The enzymatic activity was also measured on zwitterionic liposomes which appear to be much better substrates for group V PLA(2) than for group IIA PLA(2). The overall results suggest that group V PLA(2) is better suited for action on biological membranes than group IIA PLA(2).

Introduction of a C-terminal aromatic sequence from snake venom phospholipases A2 into the porcine pancreatic isozyme dramatically changes the interfacial kinetics

Porcine pancreatic phospholipase A2 (PLA2) was modified by single and multiple site-directed mutations at sites thought to be involved in interfacial binding. Charged and polar residues in the C-terminal region were replaced by aromatic residues on the basis of an analogy with snake venom PLA2s, which display high affinity for a zwitterionic interface. The PLA2 variants constructed were N117W, N117W/D119Y and K116Y/N117W/D119Y. Titration with micelles of a zwitterionic substrate suggests that the variants N117W and K116Y/N117W/D119Y possess improved ability to bind to the micellar substrate interface, relative to the wild-type enzyme. Improved interfacial binding was confirmed by direct binding studies with micelles of a zwitterionic substrate analogue, indicating up to five times higher affinity for both variants. Interfacial binding is not improved for the variant N117W/D119Y. Maximal enzyme velocities (Vapp./max) with the zwitterionic substrate were between 25 and 75% of that of the wild-type enzyme. However, competitive inhibition and direct binding studies with a strong inhibitor revealed that the affinity for substrate present at the interface (Km*) is perturbed by the mutations made. For the variant N117W, the slight decrease observed in Vapp./max is most likely made up of a 24-fold reduction in catalytic turnover (kcat) and 18-fold improved substrate binding (Km*).

Catalytic role of the active site histidine of porcine pancreatic phospholipase A2 probed by the variants H48Q, H48N and H48K

The catalytic contribution of His48 in the active site of porcine pancreatic phospholipase A2 was examined using site-directed mutagenesis. Replacement of His48 by lysine (H48K) gives rise to a protein having a distorted lipid binding pocket. Activity of this variant drops below the detection limit which is 10(7)-fold lower than that of the wild-type enzyme. On the other hand, the presence of glutamine (H48Q) or asparagine (H48N) at this position does not affect the structural integrity of the enzyme as can be derived from the preserved lipid binding properties of these variants. However, the substitutions H48Q and H48N strongly reduce the turnover number, i.e. by a factor of 10(5). Residual activity is totally lost after addition of a competitive inhibitor. We conclude that proper lipid binding on its own accelerates ester bond hydrolysis by a factor of 10(2). With the selected variants, we were also able to dissect the contribution of the hydrogen bond between Asp99 and His48 on conformational stability, being 5.2 kJ/mol. Another hydrogen bond with His48 is formed when the competitive inhibitor (R)-2-dodecanoylamino-hexanol-1-phosphoglycol interacts with the enzyme. Its contribution to binding of the inhibitor in the presence of an interface was found to be 5.7 kJ/mol.

Isolation and characterization of highly purified mitochondrial outer membranes of the yeast Saccharomyces cerevisiae (method)

Mitochondrial outer membrane vesicles (OMV) from the yeast Saccharomyces cerevisiae were prepared by osmotic swelling and mechanical disruption of mitochondria that had been isolated at pH 6.0 and purified by density gradient centrifugation. The OMV were obtained in a yield of 1% (protein/protein) with respect to the mitochondria. The OMV were shown to be essentially free of mitochondrial inner membrane protein markers, while contamination with endoplasmic reticulum was around 5% (protein-based). The very low phosphatidylserine synthase activity present in the OMV preparation indicated that contamination with mitochondria-associated membranes (MAM) was negligible. The resistance of the outer membrane protein Tom40 to digestion by trypsin demonstrated the sealed nature and right-side out orientation of the OMV. Analysis of the phospholipid composition revealed that the contents of phosphatidylcholine and phosphatidylinositol are higher and the content of phosphatidylethanolamine is lower in the mitochondrial outer membrane as compared to whole mitochondria. Cardiolipin is largely depleted in the OMV.

Engineering the disulphide bond patterns of secretory phospholipases A2 into porcine pancreatic isozyme. The effects on folding, stability and enzymatic properties

Secretory phospholipases A2 (PLA2s) are small homologous proteins rich in disulphide bridges. These PLA2s have been classified into several groups based on the disulphide bond patterns found [Dennis, E. A. (1997) Trends Biochem. Sci. 22, 1-2]. To probe the effect of the various disulphide bond patterns on folding, stability and enzymatic properties, analogues of the secretory PLA2s were produced by protein engineering of porcine pancreatic PLA2. Refolding experiments indicate that small structural variations play an important role in the folding of newly made PLA2 analogues. Introduction of a C-terminal extension together with disulphide bridge 50-131 gives rise to an enzyme that displays full enzymatic activity having increased conformational stability. In contrast, introduction of a small insertion between positions 88 and 89 together with disulphide bridge 86-89 decreases the catalytic activity significantly, but does not change the stability. Both disulphide bridges 11-77 and 61-91 are important for the kinetic properties and stability of the enzyme. Disulphide bridge 11-77, but not 61-91, was found to be essential to resist tryptic breakdown of native porcine pancreatic PLA2.

Effect of folic acid and betaine on fasting and postmethionine-loading plasma homocysteine and methionine levels in chronic haemodialysis patients

OBJECTIVES

To study fasting and postmethionine-loading (increment and decrement) plasma homocysteine levels in end-stage renal disease (ESRD) patients in relation to B-vitamin status and after folic acid treatment without or with betaine.

DESIGN

Plasma total homocysteine (tHcy) and methionine levels were measured in chronic haemodialysis patients after an overnight fast, and 6 and 24 h after an oral methionine load (0.1 g kg-1). The patients were subsequently randomized to treatment with folic acid 5 mg daily with or without betaine 4 g daily, and the loading test was repeated after 12 weeks. The patients were then re-randomized to treatment with 1 or 5 mg folic acid daily for 40 weeks, after which a third loading test was performed.

SETTING

Haemodialysis unit of university hospital and centre for haemodialysis.

SUBJECTS

Twenty-nine consecutive maintenance (> 3 months) haemodialysis patients, not on folic acid supplementation, 26 of whom completed the study.

RESULTS

At baseline, the mean fasting, the 6 h postload and the 6 h postload increment plasma tHcy levels were increased as compared with those in healthy controls (46.8 +/- 6.9 (SEM), 92.8 +/- 9.1 and 46.0 +/- 4.2 mumol L-1, respectively) and correlated with serum folate (r = -0.42, P = 0.02; r = -0.61, P = 0.001 and r = -0.54, P = 0.003, respectively), but not with vitamin B6 or vitamin B12. At week 12, these variables had all decreased significantly. Betaine did not have additional homocysteine-lowering effects. At week 52, fasting and postload tHcy levels did not differ significantly between patients on 1 or 5 mg folic acid daily. Plasma tHcy half-life and plasma methionine levels after methionine loading were not altered by folic acid treatment.

CONCLUSIONS

In chronic haemodialysis patients, fasting as well as postmethionine-loading plasma tHcy levels depend on folate status and decrease after folic acid therapy. Increased postload homocysteine levels in these patients therefore do not necessarily indicate an impaired transsulphuration capacity only; alternatively, folate may indirectly influence transsulphuration. The elucidation of the complex pathogenesis of hyperhomocysteinaemia in chronic renal failure requires further investigation.

Endothelium-dependent vasodilatation is impaired in peritoneal dialysis patients

BACKGROUND

Peritoneal dialysis (PD) patients have a high risk of cardiovascular mortality, which is not completely explained by conventional risk factors. Other factors related to chronic renal failure and/or dialysis treatment might lead to endothelial dysfunction, which is associated with an adverse cardiovascular outcome. One such factor is hyperhomocysteinaemia, which has a high prevalence in PD patients.

METHODS

A vessel wall movement detector system was used to investigate endothelium-dependent, flow-mediated, and endothelium-independent, glyceryl trinitrate-induced, vasodilatation of the brachial artery in 29 PD patients and 29 control subjects.

RESULTS

Endothelium-dependent vasodilatation was markedly reduced in the PD group: 5.7 +/- 1.0% vs 10.4 +/- 1.3% in the control group (P = 0.004). Endothelium-independent vasodilatation was not impaired. Plasma total homocysteine was elevated in the PD patients (45.2 +/- 6.2 micromol/l), but was not related to endothelium-dependent vasodilatation.

CONCLUSION

Chronic peritoneal dialysis patients have impaired endothelium-dependent vasodilatation, which may reflect an increased susceptibility for the development of atherosclerosis and thrombosis.

Folic acid treatment of hyperhomocysteinemia in peritoneal dialysis patients: no change in endothelial function after long-term therapy

BACKGROUND

Hyperhomocysteinemia occurs in renal failure and may increase the risk for cardiovascular disease, possibly by damaging the endothelium. Folic acid and betaine are required in two separate homocysteine conversion pathways and may therefore lower plasma homocysteine.

OBJECTIVE

To study the therapeutic role of betaine and the effect on endothelial function of long-term homocysteine-lowering therapy with folic acid, in peritoneal dialysis (PD) patients.

PATIENTS AND DESIGN

Thirty PD patients were randomized to a 12-week treatment with 5 mg folic acid and 4 g betaine daily, or to 5 mg folic acid alone daily. They were then rerandomized to treatment with 1 or 5 mg folic acid daily for 40 weeks.

MEASUREMENTS

At baseline and after 52 weeks, endothelial function was assessed by determination of endothelium-dependent vasodilatation and biochemical markers.

RESULTS

Plasma total homocysteine (tHcy) was elevated at baseline: 42.6 (5.8) micromol/L. Only 1 patient (3%) had a normal plasma homocysteine (i.e., < or = 15 micromol/L) before therapy. Normalization of plasma homocysteine occurred in 39% of the patients at 12 weeks. Betaine had no additional homocysteine-lowering effect. Plasma tHcy levels were similar during treatment with 1 or 5 mg folic acid daily. Endothelial function was impaired at baseline and had not improved after 52 weeks of treatment.

CONCLUSIONS

Peritoneal dialysis patients have hyperhomocysteinemia, which can be normalized with folic acid alone in about 40% of patients. Betaine does not further lower plasma homocysteine. A maintenance dose of 1 or 5 mg folic acid daily results in equivalent plasma homocysteine levels. Long-term reduction in plasma homocysteine did not result in improvement of endothelial function as assessed by our methods.

Fish oil and glycemic control in diabetes. A meta-analysis

OBJECTIVE

Hypertriglyceridemia is associated with cardiovascular disease in diabetes. Fibrates effectively lower, but do not always normalize, serum triglyceride levels. Fish oil supplements may then be added to lower serum triglyceride levels. Doubt remains whether the net effect of fish oil intake on glycemic control is beneficial in diabetes. We therefore performed a meta-analysis from published clinical trials.

RESEARCH DESIGN AND METHODS

Data sources were Medline (Cologne, Germany), Excerpta Medica, Current Contents, review articles, and published reference lists. Publications of 26 trials were selected, and all trials included more than five diabetes (IDDM and NIDDM) patients and addressed the effects of fish oil (eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) on serum lipids and glucose tolerance. We (C.E.F., M.J.F.M.J.) extracted data independently based on predetermined criteria. Studies were classified according to design.

RESULTS

All studies combined showed a decrease in mean triglyceride concentrations in association with fish oil: -0.60 mmol/l (95% CI, -0.84 to -0.33, P < 0.01) and a slight but significant increase in serum LDL cholesterol: 0.18 mmol/l (95% CI, 0.04-0.32, P = 0.01), with both findings most prominent in NIDDM. No significant changes in HbA1c percentages occurred in diabetic subjects treated with fish oil. Fasting blood glucose levels were increased with borderline significance in NIDDM subjects (0.43 mmol/l [95% CI, 0.00-0.87], P = 0.06) and were significantly lower in IDDM subjects (-1.86 mmol/l [95% CI, -3.1 to -0.61], P < 0.05). Significant dose-response effects of EPA (g/day) on HbA1c and triglycerides and of DHA (g/day) on fasting blood glucose levels, HbA1c, and triglycerides were demonstrated only in NIDDM subjects.

CONCLUSIONS

The use of fish oil has no adverse affects on HbA1c in diabetic subjects and lowers triglyceride levels effectively by almost 30%. However, this may be accompanied by a slight increase in LDL cholesterol concentration. Fish oil may be useful in treating dyslipidemia in diabetes.

The effect of renal transplantation on hyperhomocysteinaemia in dialysis patients, and the estimation of renal homocysteine extraction in patients with normal renal function

BACKGROUND

The pathophysiology of hyperhomocysteinaemia in chronic renal failure (CRF) is unknown. Possible mechanisms are decreased renal homocysteine (Hcy) catabolism or inhibition of extrarenal Hcy metabolism by uraemic toxins.

METHODS

We studied the short-term effect on plasma Hcy concentration of improvement of renal function after successful kidney transplantation (n = 8), and determined renal Hcy extraction by measurement of total Hcy in arterial and renal venous blood in 7 cardiac patients with normal renal function.

RESULTS

Post-transplantation, plasma Hcy decreased with improving renal function. In the cardiac patients, no significant renal Hcy extraction could be demonstrated, but tubular disposal of the filtered load could not be excluded.

CONCLUSIONS

Because loss of such renal metabolism could lead to hyperhomocysteinaemia in CRF, it is necessary to determine the renal extraction of free Hcy in subjects with normal renal function to further investigate renal homocysteine metabolism.

No change in impaired endothelial function after long-term folic acid therapy of hyperhomocysteinaemia in haemodialysis patients

BACKGROUND

Hyperhomocysteinaemia is frequent in chronic haemodialysis patients. Because of its potential role in athero- and thrombogenesis, the effects of long-term homocysteine-lowering treatment on endothelial function are of interest.

METHODS

We conducted a randomized, controlled trial in 35 haemodialysis patients. In phase 1, patients were treated with 5 mg folic acid or 5 mg folic acid and 4 g betaine per day for 12 weeks, and in phase 2 with 1 or 5 mg folic acid daily for 40 weeks. In phase 3, all patients received 15 mg folic acid daily for four weeks. Endothelial function was assessed before and after 52 weeks of treatment by determination of flow-mediated vasodilatation of the brachial artery, and by measuring plasma levels of endothelium-derived proteins.

RESULTS

Non-fasting predialysis plasma total homocysteine was markedly elevated at baseline (46.9 +/- 6.3 mumol/l) and decreased rapidly after initiation of therapy. Significant differences in plasma homocysteine between the groups were found neither during phase 1 nor phase 2. Plasma total homocysteine had normalized in only two out of 30 patients at the end of phase 2. Increasing the daily folic acid dose to 15 mg did not further reduce plasma total homocysteine. Endothelial function parameters did not improve.

CONCLUSIONS

We concluded that betaine is not effective in conjunction with folic acid in the treatment of hyperhomocysteinaemia in haemodialysis patients. Normalization of plasma total homocysteine is seldom achieved with 1, 5 or 15 mg folic acid daily, which may explain why long-term homocysteine-lowering treatment with 1 or 5 mg folic acid does not ameliorate endothelial function.

Stability of solubilized benzodiazepine receptors

According to the observations of other researchers, benzodiazepine receptors solubilized with sodium deoxycholate are unstable, but stability can be improved by exchanging deoxycholate for Triton X-100. In our experiments we conclude that the choice of detergent is not the restrictive factor for the stability of the solubilized receptors, but the storage conditions are. Solubilized receptors, either stored in sodium deoxycholate or in Triton X-100, were stable for at least 2 months when stored at -80 degrees C, but both preparations were strongly unstable when stored at -20 degrees C. Alternatively, sodium deoxycholate-solubilized receptors may be lyophilized and then stored at -20 degrees C.

Endothelium-dependent vasodilatation and distensibility of large arteries in chronic haemodialysis patients

BACKGROUND

Cardiovascular mortality is increased in chronic haemodialysis (HD) patients and is not completely explained by common cardiovascular risk factors. Hyperhomocysteinaemia and chronic HD per se may play a role, because these factors may adversely affect endothelial function and distensibility of conduit arteries, which are important determinants of the risk of atherosclerosis, thrombosis and cardiac hypertrophy.

METHODS

A vessel wall movement detector system was used to investigate endothelium-dependent, flow-mediated and endothelium-independent, glyceryl trinitrate-induced vasodilatation in the brachial artery and compliance and distensibility coefficients (CC and DC) in the common carotid artery in 28 chronic HD patients and 28 control subjects.

RESULTS

Endothelium-dependent, but not endothelium-independent, vasodilatation was markedly reduced in the HD group (3.7 +/- 1.1 vs. 9.7 +/- 1.2%; P = 0.001). The DC was reduced only in a subgroup of patients aged < 50 years: 16.9 +/- 1.5 vs. 22.4 +/- 2.0 10(-3)/kPa (P = 0.032) and was not related to endothelium-dependent vasodilatation. CC did not differ between the groups. Plasma total homocysteine was elevated in the HD patients, but was neither related to endothelium-dependent vasodilatation, nor to DC.

CONCLUSION

Chronic renal failure and (or) chronic haemodialysis are associated with impaired endothelium-dependent vasodilatation, which may reflect an increased susceptibility for the development of atherosclerosis and thrombosis.

Efficacy of low-dose desferrioxamine for the estimation of aluminium overload in haemodialysis patients

In haemodialysis patients the desferrioxamine (DFO) test is an accepted method for estimating the body content of aluminium. However, toxic side effects have been frequently reported with the high-dose (30 or 40 mg/kg) DFO tests. To study if a low-dose (500 mg) DFO test was also useful and free of side effects, we compared it with a high-dose DFO test in 22 patients on regular haemodialysis. During the first two hours of dialysis, 500 mg DFO in 100 ml 0.9% NaCl were administered intravenously. Before dialysis and after 48 hours aluminium concentration was determined in serum. In 14 patients the low-dose DFO test was considered positive. In 11 of those 14 patients the high-dose (30 mg/kg) DFO test was positive too. Analysis of the results showed a significant correlation (p < 0.05) between the outcome of the two DFO tests in the same patient. Compared to the high-dose DFO test, the low-dose test revealed a sensitivity of 79% and a specificity of 63%. In contrast with the high-dose DFO test might be a reliable and safe method for the estimation of the body content of aluminium in patients on regular haemodialysis.

Solubilized benzodiazepine receptors for use in receptor assays

In the development of non-radioactive receptor assays for benzodiazepines, employing fluorescent ligands, it was observed that the fluorescence measurements were hampered by the background fluorescence of the receptor preparation. This receptor preparation is a brain tissue homogenate in which the benzodiazepine receptors are membrane-bound. To minimize the influence of the receptor material on the fluorescence detection, the benzodiazepine receptors were solubilized with 0.5% sodium deoxycholate. The binding characteristics of the receptors were examined after solubilization and compared with membrane-bound receptors. The Kd and Bmax values for membrane-bound receptors were 1.20 nM and 1.01 pM mg-1 protein and for solubilized receptors they were 4.1 nM and 0.54 pM mg-1 protein respectively. Inhibition curves with the benzodiazepine antagonist flumazenil and the agonist lorazepam revealed that their affinities for the solubilized receptor as compared to the membrane-bound receptor were also reduced from 0.67 nM to 3.2 nM and from 1.49 nM to 8.4 nM respectively. The detection limits for the two benzodiazepines, however, were not affected by the solubilization. Furthermore, three different methods to separate the fraction of free labelled ligand and the fraction bound to the solubilized receptor were compared, namely polyethylene glycol precipitation/filtration, ion exchange filtration and charcoal adsorption. Polyethylene glycol precipitation/filtration gave the highest yield for the bound fraction and the best reproducibility.

The bleeding risk in chronic haemodialysis: preventive strategies in high-risk patients

Haemodialysis (HD) patients are at an increased risk of bleeding because of uraemic bleeding tendency and systemic anticoagulation caused by intermittent heparinization. Additional risk factors may be aspirin or coumarin use for the prevention of fistula thrombosis, diffuse intravascular coagulation, recent trauma, postsurgical state, inadequate control of hypertension, gastrointestinal lesions, diabetic retinopathy, renal cystic disease, and uraemic pericarditis. In HD patients with an active bleeding focus blood transfusion, desmopressin acetate (DDAVP), conjugated oestrogens, and dialysis treatment can limit the bleeding risk. Strategies to reduce the bleeding risk conveyed by systemic anticoagulation during HD are regional heparin anticoagulation and minimal heparinization. In our opinion, dialytic modalities that completely preclude systemic anticoagulation, i.e. peritoneal dialysis (PD), heparin-free HD, and HD with regional anticoagulation with prostacyclin, mesilates, or citrate, are indicated for patients who are actively bleeding, or who are within 3 days from a bleeding episode, or a surgical or accidental wound, or who are less than 2 weeks from cerebral or retinal haemorrhage, and for patients with incompletely treated proliferative diabetic retinopathy or uraemic pericarditis.