FcRn binding properties of an abnormal truncated analbuminemic albumin variant

Background:The major histocompatibility class I-related neonatal Fc receptor, FcRn, salvages both IgG and albumin from degradation and thus contributes to maintain high serum levels of these proteins. Analbuminemia is a rare autosomal recessive disorder characterized by clinically observed allelic albumin variants that are absent or found in very low concentrations in the blood circulation. Such variants may have altered FcRn binding properties that affect their half-life, biodistribution and thereby transport ability.Methods:We established an easy cloning, expression and purification strategy to obtain recombinant GST-tagged human serum albumin (HSA) variants for evaluation of pH dependent FcRn binding properties using an enzyme-linked immunosorbent assay (ELISA) and a real time surface plasmon resonance (SPR) biosensor system.Results:The strategy yielded purified GST-tagged albumin variants. A recombinant truncated HSA variant similar to a clinically observed splice mutant denoted Bartin, here abrogated HSA^Bartin, showed no detectable pH dependent FcRn binding compared to a fully functional albumin wild type variant, HSA^Wt, and a truncated HSA variant consisting of only the carboxy terminal domain III (HSA^DIII).Conclusions:The approach described can be used to rapidly screen clinically observed truncated or otherwise mutant or modified HSA variants regarding their pH dependent FcRn binding properties. Here, we demonstrate that a recombinant truncated HSA variant, HSA^Bartin, does not interact with FcRn, which gives a molecular explanation for the low serum levels. In addition, DIII of HSA alone was shown to retain its FcRn binding property.     

DNA methylation profiling of ovarian carcinomas and their in vitro models identifies HOXA9, HOXB5, SCGB3A1, and CRABP1 as novel targets

Background  

The epigenetics of ovarian carcinogenesis remains poorly described. We have in the present study investigated the promoter methylation status of 13 genes in primary ovarian carcinomas (n = 52) and their in vitro models (n = 4; ES-2, OV-90, OVCAR-3, and SKOV-3) by methylation-specific polymerase chain reaction (MSP). Direct bisulphite sequencing analysis was used to confirm the methylation status of individual genes. The MSP results were compared with clinico- pathological features.     

The effect of B-vitamins on hyperhomocysteinemia in patients on antiepileptic drugs

Patients on antiepileptic drugs (AEDs) may have elevated levels of plasma total homocysteine (p-tHcy). The aim of this study was to assess the effect of B-vitamin supplementation on the levels of p-tHcy and markers of endothelial activation and lipid peroxidation. A total of 33 adult patients on AEDs were identified with either fasting (Group 1, n=23) or post methionine load (PML) (Group 2, n=10) hyperhomocysteinemia. Subjects were supplemented with B-vitamins for 30 days: folic acid 0.4 mg, pyridoxine 120 mg and riboflavin 75 mg per day. After supplementation, serum folate and pyridoxal phosphate had increased, while fasting and PML p-tHcy had decreased (P<0.0001) by 36 and 26%, respectively. Prior to supplementation, the Group 1 patients had elevated levels of P-selectin and von Willebrand factor (vWF) (P=0.05 and 0.03, respectively). After supplementation, the levels of intercellular cell adhesion molecules had decreased (P=0.01) and E-selectin decreased nonsignificantly (P=0.07). However, the levels of vascular cell adhesion molecules had increased (P<0.0001), while lipid peroxidation were unchanged. In conclusion, the combined supplementation with folic acid, pyridoxine and riboflavin reduced fasting and PML hyperhomocysteinemia in patients on AEDs. Patients with fasting hyperhomocysteinemia had elevated levels of P-selectin and vWF, which may indicate an increased risk of cardiovascular disease. Furthermore, B-vitamin supplementation influenced endothelial activation, although the clinical implication is uncertain.     

In vitro agreement between magnetic resonance imaging and intraluminal Doppler ultrasound for high flow velocity measurements

OBJECTIVE: Differences of opinion in the literature about the agreement between magnetic resonance imaging (MRI) and ultrasound Doppler (USD) for high blood velocity measurement were the basis for this investigation. It compares in vitro velocity measurements by MRI with intraluminal USD, using a specially designed flow phantom. DESIGN: The flow phantom consisted of a pulsatile pump, tubing, a prosthetic heart valve, measurement sections and a reservoir. Peak systolic velocities (0.7-5.0 m/s, n = 10) were measured with standard MRI phase shift velocity mapping using different regions of interest (ROIs). Intravascular USD velocity measurements were carried out using a thin cannula measuring peak systolic local maximum and local mean velocity within the small sample volume. RESULTS: Using maximum velocity USD recordings, comparison with MRI velocities was poor when the ROI covered the complete vessel lumen giving offset -22.3% and limits of agreement (LOA) 57.5 and 105.1%. When the ROI was small the velocities were closer with offset -11.8% and LOA 75.3-103.3%. When the spatial resolution was comparable and the spatial mean was read from the USD recordings, the velocities showed good agreement with an offset close to zero (0.45%). CONCLUSION: This study shows the importance of selecting small ROIs when using MRI for evaluating valve stenosis. Only when using spatially mean velocities over comparable regions the two methods showed good agreement.     

Altered dopaminergic function in the prefrontal cortex, nucleus accumbens and caudate-putamen of an animal model of attention-deficit hyperactivity disorder — the spontaneously hypertensive rat

The spontaneously hypertensive rat (SHR) has been proposed as an animal model for Attention-Deficit Hyperactivity Disorder (ADHD). The behavioural problems of ADHD have been suggested to be secondary to altered reinforcement mechanisms resulting from dysfunction of the mesolimbic and mesocortical dopaminergic systems. The present study therefore investigated whether there are regional differences in dopamine (DA) and acetylcholine (ACh) release and DA D₂-receptor function in SHR compared to their normotensive Wistar-Kyoto (WKY) controls. The DA D₂-receptor agonist, quinpirole, caused significantly greater inhibition of DA release from caudate-putamen but not from nucleus accumbens or prefrontal cortex slices of SHR relative to WKY. DA D₂-receptor blockade by the antagonist, sulpiride, caused a significantly greater increase in DA release from nucleus accumbens slices of SHR compared to WKY suggesting increased efficacy of DA autoreceptors at low endogenous agonist concentrations in the nucleus accumbens of SHR. The electrically-stimulated release of DA was significantly lower in caudate-putamen and prefrontal cortex slices of SHR than in slices of WKY. This could be attributed to increased autoreceptor-mediated inhibition of DA release in caudate-putamen slices but not in the prefrontal cortex. No difference was observed between SHR and WKY with respect to DA D₂-receptor-mediated inhibition of ACh release from caudate-putamen or nucleus accumbens slices, suggesting that postsynaptic DA D₂-receptor function is not altered in SHR relative to WKY.     

Effect of diethylstilbestrol and estramustine phosphate (estracyt®) on delayed hypersensitivity response to oxazolone in male mice

The effects of diethylstilbestrol (DES) and estramustine phosphate (EMP) on delayed hypersensitivity response (DTH) to oxazolone in male mice were investigated using a radioisotopic ear method. DES significantly inhibited the ability to express a DTH response and was most effective when given during the effector phase of the reaction. EMP had no effects when the animals were exposed to the drug during the effector phase, while it resulted in a strong and dose-dependent depression of the DTH response when applied in the sensitization phase. Possible involvement of suppressor cells was investigated by pretreatment of animals with cyclophosphamide or by adoptive transfer of tentative suppressor cells from spleen, lymph nodes, or peritoneal cavity. However, no evidence of cellular or humoral suppressor factors induced by drug treatment was found.     

Moment-to-moment dynamics of ADHD behaviour

Background  

The behaviour of children with Attention-Deficit / Hyperactivity Disorder is often described as highly variable, in addition to being hyperactive, impulsive and inattentive. One reason might be that they do not acquire complete and functional sequences of behaviour. The dynamic developmental theory of ADHD proposes that reinforcement and extinction processes are inefficient because of hypofunctioning dopamine systems, resulting in a narrower time window for associating antecedent stimuli and behaviour with its consequences. One effect of this may be that the learning of behavioural sequences is delayed, and that only short behavioural sequences are acquired in ADHD. The present study investigated acquisition of response sequences in the behaviour of children with ADHD.     

Behavioral effects of intra-cranial self-stimulation in an animal model of attention-deficit/hyperactivity disorder (ADHD)

Attention deficit/hyperactivity disorder (ADHD), characterized by inappropriate levels of activity, attention, and impulsivity, has been suggested to be caused by changes in reinforcement and extinction processes possibly linked to dysfunctioning dopamine systems. The present study investigated reinforcement processes in spontaneously hypertensive rats (SHR), an animal model of ADHD. Using intra-cranial self-stimulation (ICSS), behavioral effects of varying current intensity, reinforcer density, and reinforcer delay were tested. Current was varied in order to find the weakest current producing the maximal response rate (optimal current) in the SHR and the controls during high (120 reinforcers/min) and low reinforcer densities (1 reinforcer/min). The results showed that optimal current was significantly lower in the SHR than in the controls during high reinforcer density while maximal response rates were not significantly different. During low reinforcer density, optimal current was not significantly different in the two strains, but maximal response rate was significantly higher in the SHR than in the controls. The SHR produced more responses during the testing of reinforcer density, but changes in reinforcer density affected response rates similarly in the two strains. The decrease in response rate as a function of reinforcer delay was more pronounced in the SHR than in the controls. Overall, more responses with short inter-response times (IRT) were found in the SHR compared to the controls during intermittent reinforcement. The results are consistent with a steepened delay-of-reinforcement gradient in SHR.     

Effects of delayed reinforcers on the behavior of an animal model of attention-deficit/hyperactivity disorder (ADHD)

Attention-deficit/hyperactivity disorder (ADHD), affecting 3-5% of grade-school children, is a behavioral disorder characterized by developmentally inappropriate levels of inattention, hyperactivity, and impulsivity. It has been suggested that the symptoms are caused by altered reinforcement and extinction processes, behaviorally described as an abnormally short and steep delay-of-reinforcement gradient in ADHD. The present study tested predictions from the suggested shortened and steepened delay gradient in ADHD in an animal model, the spontaneously hypertensive rats (SHRs). It was predicted that SHR responding during baseline would mainly consist of responses with short inter-response times, and that responding would be more rapidly reduced in the SHR than in the controls by the introduction of a time interval between the response and reinforcer delivery. Effects of a resetting delay of reinforcement procedure with water as the reinforcer were tested on two baseline reinforcement schedules: variable interval 30 s (VI 30 s) and conjoint variable interval 60 s differential reinforcement of high rate 1s (VI 60 s DRH 1 s). The results showed a higher rate of responses in the SHR than in the controls during baseline, mainly consisting of responses with short inter-response times. The statistical analyses showed that response rates decreased more rapidly as a function of reinforcer delay in the SHR than in the controls. The analyses of the estimates of the reinforcer decay parameter showed no strain differences during the VI 30 s schedule but showed a significant strain difference at the end, but not at the start, of the sessions during the VI 60 s DRH 1 s schedule. In general, the results support predictions from the suggested steepened delay gradient in SHR. However, the predictions were only partly confirmed by the analyses of the decay parameter.