Characterization of low affinity Fcγ receptor biotinylation under controlled reaction conditions by mass spectrometry and ligand binding analysis

Chemical protein biotinylation and streptavidin or anti-biotin-based capture is regularly used for proteins as a more controlled alternative to direct coupling of the protein on a biosensor surface. On biotinylation an interaction site of interest may be blocked by the biotin groups, diminishing apparent activity of the protein. Minimal biotinylation can circumvent the loss of apparent activity, but still a binding site of interest can be blocked when labeling an amino acid involved in the binding. Here, we describe reaction condition optimization studies for minimal labeling. We have chosen low affinity Fcγ receptors as model compounds as these proteins contain many lysines in their active binding site and as such provide an interesting system for a minimal labeling approach. We were able to identify the most critical parameters (protein:biotin ratio and incubation pH) for a minimal labeling approach in which the proteins of choice remain most active toward analyte binding. Localization of biotinylation by mass spectrometric peptide mapping on minimally labeled material was correlated to protein activity in binding assays. We show that only aiming at minimal labeling is not sufficient to maintain an active protein. Careful fine-tuning of critical parameters is important to reduce biotinylation in a protein binding site.

A comparison of anti-HER2 IgA and IgG1 in vivo efficacy is facilitated by high N-glycan sialylation of the IgA

Monomeric IgA has been proposed as an alternative antibody format for cancer therapy. Here, we present our studies on the production, purification and functional evaluation of anti-HER2 IgA antibodies as anti-cancer agents in comparison to the anti-HER2 IgG1 trastuzumab. MALDI-TOF MS analysis showed profound differences in glycosylation traits across the IgA isotypes and cell lines used for production, including sialylation and linkage thereof, fucosylation (both core and antennary) and the abundance of high-mannose type species. Increases in sialylation proved to positively correlate with in vivo plasma half-lives. The polymerization propensity of anti-HER2 IgA2m2 could be suppressed by an 18-aa deletion of the heavy chain tailpiece - coinciding with the loss of high-mannose type N-glycan species - as well as by 2 cysteine to serine mutations at positions 320 and 480. The HER2 F(ab')2-mediated anti-proliferative effect of the IgA2m1 and IgA2m2 subtypes was similar to IgG1, whereas the IgA1 isotype displayed considerably lower potency and efficacy. The Fc-mediated induction of antibody-dependent cell-mediated cytotoxicity (ADCC) using human whole blood ADCC assays did not demonstrate such clear differences between the IgA isotypes. However, the potency of the anti-HER2 IgA antibodies in these ADCC assays was found to be significantly lower than that of trastuzumab. In vivo anti-tumor activity of the anti-HER2 IgA antibodies was compared to that of trastuzumab in a BT-474 breast cancer xenograft model. Multiple dosing and sialylation of the IgA antibodies compensated for the short in vivo half-life of native IgA antibodies in mice compared to a single dose of IgG1. In the case of the IgA2m2 antibody, the resulting high plasma exposure levels were sufficient to cause clear tumor stasis comparable to that observed for trastuzumab at much lower plasma exposure levels.

232 ADDITION OF VERY LOW AMOUNTS OF SERUM (ESTRUS COW SERUM) IMPROVES IN VITRO EMBRYO PRODUCTION IN DAIRY CATTLE

Improving the efficiency of the in vitro production (IVP) process is very important because it results in more embryos to be used in breeding programs or as commercial service. At CRV, a culture medium consisting of SOF with amino acids and BSA is used. In the past, richer culture media were used with 10% fetal calf serum combined with BRL cell co-culture. Although the efficiency of the IVP process of these media was good, these rather high serum concentrations were quite often related to large offspring syndrome (LOS). The switch to a culture system without serum resulted in a significant reduction in LOS but also in a reduction of embryo yield. The aim of the present study was to investigate the effect of adding low amounts of serum to the culture medium on efficiency of embryo production. Immature cumulus-oocyte complexes (COC) were recovered from ovaries 6 to 8 h upon slaughter. The COC were matured in vitro in TCM199/FCS/LH/FSH supplemented with cysteamine (0.1 mM). Subsequently, matured oocytes were fertilised with frozen-thawed gradient-separated semen and further cultured for 7 days in SOFaaBSA. The SOF medium contained either 0 (control), 0.1, 0.5, or 1.0% oestrus cow serum (ECS). Embryos development was scored at Day 7. Three replicates were performed and results were analysed by chi-square analyses. The results clearly show that adding ECS significantly improved embryo production (Table 1). Interestingly, already very low amounts (0.1%) of serum gave a significant increase in embryo percentage. In conclusion, addition of very low amounts of ECS (0.1%) is beneficial for embryo production, resulting in significantly higher embryo production (from 19 to 27%). In a subsequent field trial with OPU-derived embryos, the effect of addition of 0.1% ECS on birth weight (LOS) of the calves has to be investigated. Table 1.Percentage of blastocysts at Day 7 after culture in SOF medium with different amounts of serum

240 OVUM-PICK UP IN HOLSTEIN-FRIESIAN COWS AT 9 TO 10 MONTHS OF AGE

Rate of genetic gain can be improved by increasing selection intensity, increasing selection accuracy, creating a higher amount of variation, or shortening the generation interval. A reduction in the generation interval can be realised by collecting embryos from animals at a young age. At CRV it is currently routine practice to start embryo collection (by flushing) at 12 to 15 months of age. The aim of this study was to investigate if the collection of embryos at a younger age by means of ovum pickup (OPU) is beneficial for our breeding program. Healthy 9- to 10-month-old Holstein-Friesian animals were selected at young age based on their maturity, (i.e. OPU could be performed by normal standard procedure/equipment). Animals were not stimulated with hormones. Oocytes were collected by OPU once every week during a period of ~8 weeks. Collected oocytes were matured, fertilized, and cultured for 7 days in SOF culture medium according to standard procedures (Merton et al. 2002). Embryo development was scored at Day 7. Results were analysed by Student's t-test. On average 11.7 oocytes were collected from animals as young as 9 months of age. However, embryo development of the oocytes from young animals was only 0.4 embryo per session at Day 7 (3% embryo development). When only the results of the first OPU session were taken into account, 18.2 oocytes and 0.8 embryo could be collected per animal per session. Whether an animal was observed in oestrus before the first OPU session affected results. Animals that had shown clear signs of oestrus before the first OPU session produced significantly more embryos than animals that did not (Table 1). It is concluded that OPU is possible on animals at 9 to 10 months of age but only when animals have been in oestrus before the first OPU session. Best results were obtained for the first OPU session. Table 1.Effect of first oestrus before OPU on embryo production

Screening of congenital heart disease patients using multiplex ligation-dependent probe amplification: early diagnosis of syndromic patients

Recurrent copy number variants (CNVs) are found in a significant proportion of patients with congenital heart disease (CHD) and some of these CNVs are associated with other developmental defects. In some syndromic patients, CHD may be the first presenting symptom, thus screening of patients with CHD for CNVs in specific genomic regions may lead to early diagnosis and awareness of extracardiac symptoms. We designed a multiplex ligation-dependent probe amplification (MLPA) assay specifically for screening of CHD patients. The MLPA assay allows for simultaneous analysis of CNVs in 25 genomic regions previously associated with CHD. We screened blood samples from 402 CHD patients and identified 14 rare CNVs in 13 (3.2%) patients. Five CNVs were de novo and six where inherited from a healthy parent. The MLPA screen led to early syndrome diagnosis in two of these patients. We conclude that the MLPA assay detects clinically relevant CNVs and suggest that it could be used within pediatric cardiology as a first tier screen to detect clinically relevant CNVs and identify syndromic patients at an early stage.

The role of the expected value of individualized care in cost-effectiveness analyses and decision making

OBJECTIVE

To explore the feasibility and potential role of the expected value of individualized care (EVIC) framework.

METHODS

The EVIC quantifies how much benefits are forgone when a treatment decision is based on the best-expected outcomes in the population rather than in the individual patient. We have reviewed which types of patient-level attributes contribute to the EVIC and how they affect the interpretation of the outcomes. In addition, we have applied the EVIC framework to the outcomes of a microsimulation-based cost-effectiveness analysis for glaucoma treatment.

RESULTS

For EVIC outcomes to inform decisions about clinical practice, we need to calculate the parameter-specific EVIC of known or knowable patient-level attributes and compare it with the real costs of implementing individualized care. In the case study, the total EVIC was €580 per patient, but patient-level attributes known at treatment decision had minimal impact. A subgroup policy based on individual disease progression could be worthwhile if a predictive test for glaucoma progression could be developed and implemented for less than €130 per patient.

CONCLUSIONS

The EVIC framework is feasible in cost-effectiveness analyses and can be informative for decision making. The EVIC outcomes are particularly informative when they are (close to) zero. When the EVIC has a high value, implications depend on the type of patient-level attribute. EVIC can be a useful tool to identify opportunities to improve efficiency in health care by individualization of care and to quantify the maximal investment opportunities for implementing subgroup policy.

The impact of HIV/HCV co-infection on health care utilization and disability: results of the ACTG Longitudinal Linked Randomized Trials (ALLRT) Cohort

HIV/hepatitis C virus (HCV) co-infection places a growing burden on the HIV/AIDS care delivery system. Evidence-based estimates of health services utilization among HIV/HCV co-infected patients can inform efficient planning. We analyzed data from the ACTG Longitudinal Linked Randomized Trials (ALLRT) cohort to estimate resource utilization and disability among HIV/HCV co-infected patients and compare them to rates seen in HIV mono-infected patients. The analysis included HIV-infected subjects enrolled in the ALLRT cohort between 2000 and 2007 who had at least one CD4 count measured and completed at least one resource utilization data collection form (N = 3143). Primary outcomes included the relative risk of hospital nights, emergency department (ED) visits, and disability days for HIV/HCV co-infected vs HIV mono-infected subjects. When controlling for age, sex, race, history of AIDS-defining events, current CD4 count and current HIV RNA, the relative risk of hospitalization, ED visits, and disability days for subjects with HIV/HCV co-infection compared to those with HIV mono-infection were 1.8 (95% CI: 1.3-2.5), 1.7 (95% CI: 1.4-2.1), and 1.6 (95% CI: 1.3-1.9) respectively. Programs serving HIV/HCV co-infected patients can expect approximately 70% higher rates of utilization than expected from a similar cohort of HIV mono-infected patients.

Germline CDH1 deletions in hereditary diffuse gastric cancer families

Germline CDH1 point or small frameshift mutations can be identified in 30-50% of hereditary diffuse gastric cancer (HDGC) families. We hypothesized that CDH1 genomic rearrangements would be found in HDGC and identified 160 families with either two gastric cancers in first-degree relatives and with at least one diffuse gastric cancer (DGC) diagnosed before age 50, or three or more DGC in close relatives diagnosed at any age. Sixty-seven carried germline CDH1 point or small frameshift mutations. We screened germline DNA from the 93 mutation negative probands for large genomic rearrangements by Multiplex Ligation-Dependent Probe Amplification. Potential deletions were validated by RT-PCR and breakpoints cloned using a combination of oligo-CGH-arrays and long-range-PCR. In-silico analysis of the CDH1 locus was used to determine a potential mechanism for these rearrangements. Six of 93 (6.5%) previously described mutation negative HDGC probands, from low GC incidence populations (UK and North America), carried genomic deletions (UK and North America). Two families carried an identical deletion spanning 193 593 bp, encompassing the full CDH3 sequence and CDH1 exons 1 and 2. Other deletions affecting exons 1, 2, 15 and/or 16 were identified. The statistically significant over-representation of Alus around breakpoints indicates it as a likely mechanism for these deletions. When all mutations and deletions are considered, the overall frequency of CDH1 alterations in HDGC is approximately 46% (73/160). CDH1 large deletions occur in 4% of HDGC families by mechanisms involving mainly non-allelic homologous recombination in Alu repeat sequences. As the finding of pathogenic CDH1 mutations is useful for management of HDGC families, screening for deletions should be offered to at-risk families.

MLPAnalyzer: data analysis tool for reliable automated normalization of MLPA fragment data

Background: Multiplex Ligation dependent Probe Amplification (MLPA) is a rapid, simple, reliable and customized method for detection of copy number changes of individual genes at a high resolution and allows for high throughput analysis. This technique is typically applied for studying specific genes in large sample series. The large amount of data, dissimilarities in PCR efficiency among the different probe amplification products, and sample-to-sample variation pose a challenge to data analysis and interpretation. We therefore set out to develop an MLPA data analysis strategy and tool that is simple to use, while still taking into account the above-mentioned sources of variation.

Materials and Methods: MLPAnalyzer was developed in Visual Basic for Applications, and can accept a large number of file formats directly from capillary sequence systems. Sizes of all MLPA probe signals are determined and filtered, quality control steps are performed, and variation in peak intensity related to size is corrected for. DNA copy number ratios of test samples are computed, displayed in a table view and a set of comprehensive figures is generated. To validate this approach, MLPA reactions were performed using a dedicated MLPA mix on 6 different colorectal cancer cell lines. The generated data were normalized using our program and results were compared to previously performed array-CGH results using both statistical methods and visual examination.

Results and Discussion: Visual examination of bar graphs and direct ratios for both techniques showed very similar results, while the average Pearson moment correlation over all MLPA probes was found to be 0.42. Our results thus show that automated MLPA data processing following our suggested strategy may be of significant use, especially when handling large MLPA data sets, when samples are of different quality, or interpretation of MLPA electropherograms is too complex. It remains, however, important to recognize that automated MLPA data processing may only be successful when a dedicated experimental setup is also considered.

MLPA for prenatal diagnosis of commonly occurring aneuploidies

Multiplex ligation-dependent probe amplification (MLPA) is a new method to determine the copy number of up to 45 genomic DNA sequences in a single multiplex polymerase chain reaction (PCR)-based reaction. In contrast to standard multiplex PCR, only one pair of PCR primers is used. MLPA reactions with currently commercial available kits result in very reproducible gel patterns with fragments of 130 to 480 bp that can be analyzed by sequence type electrophoresis. Comparison of this gel pattern to that obtained from a control sample indicates which sequences show an aberrant copy number.

Serotonin transporter polymorphisms and the occurrence of adverse events during treatment with selective serotonin reuptake inhibitors

During treatment with selective serotonin reuptake inhibitors, some patients experience adverse events whereas others do not. Assessment of predictors for selective serotonin reuptake inhibitors-induced adverse events would be useful for the identification of patients likely to develop these events. This study evaluates the association between adverse events during selective serotonin reuptake inhibitor treatment and two polymorphisms in the serotonin transporter (5-HTTLPR and STin2) gene. We included 214 patients meeting Diagnostic and statistical manual of mental disorder-IV criteria for major depression and using an selective serotonin reuptake inhibitor for at least 6 weeks. Blood samples or buccal swabs were taken to determine 5-HTTLPR and STin2 genotype. Information on adverse events was gathered through interviews and general practitioners' files. The association between serotonin transporter genotype and adverse events was assessed by use of logistic regression. Patients with the 5-HTTLPR s/s or s/l genotype appeared to have an increased risk of adverse events, especially general adverse events (dermatologic reactions, weight change and fatigue); odds ratio 1.77 (95% confidence interval 0.80-3.92) for the s/s genotype, odds ratio 2.37 (95% confidence interval 1.13-4.96) for the s/l genotype. For STin2, results were inconsistent and observed associations were weak and statistically nonsignificant. Our findings indicate that patients with the 5-HTTLPR s/s or s/l genotype have an increased risk of developing adverse events during selective serotonin reuptake inhibitor treatment.

Treatment of cirrhotic ascites

Cirrhosis is the most common cause of ascites and accounts for almost 85% of all cases. It is the most common complication of cirrhosis, after development of ascites only 50% of patients will survive for 2 to 5 years. Successful treatment is dependent on accurate diagnosis of the cause of ascites. Because sodium and water retention is the basic abnormality leading to ascites formation, restriction of sodium intake and enhancing sodium excretion is the mainstay of the treatment of ascites. Patients with cirrhosis and ascites must limit sodium intake to 2 gram per day. Enhancement of sodium excretion can be accomplished by usage of oral diuretics. The recommended initial dose is spironolactone 100-200 mg/d and furosemide 20-40 mg/d. usual maximum doses are 400 mg/d of spironolactone and 160 mg/d of furosemide. The recommended weight loss in patients without peripheral edema is 300 to 500 g/d. There is no limit to the daily weight loss of patients who have edema. About 90% of patients respond well to medical therapy for ascites. Refractory ascites is defined as fluid overload that is unresponsive to sodium restricted diet and high dose diuretic treatment (diuretic resistant) or when there is an inability to reach maximal dose of diuretics because of adverse effects (diuretic-intractable). It has a poor prognosis. Treatment options for patients with refractory ascites are serial therapeutic paracentesis, transjugular intrahepatic stent-shunt (TIPS) or peritoneovenous shunt and liver transplantation. TIPS should be considered in patients who repeatedly fail large-volume paracentesis and have relatively preserved liver functions. Liver transplantation is the only modality that is associated with improved survival.

Clinical indicators: development and applications

Clinical indicators give an indication of the quality of the patient care delivered. They must comply with highquality standards and should be constructed in a careful and transparent manner. Indicators must be relevant to the important aspects of quality of care. There should be adequate research evidence that the recommendations from which they are derived are related to clinical effectiveness, safety and efficiency. They should measure the quality in a valid and reliable manner with little inter- and intra-observer variability so that they are suitable for comparisons between professionals, practices, and institutions. Indicators are selected from research data with consideration for optimal patient care (preferably an evidence-based guideline), supplemented by expert opinion. In the selection procedure, the feasibility, such as their measurability and improvability, is important beside validity and reliability. A clinical indicator should be defined exactly and expressed as a quotient. After a try-out, the measurements and reporting should follow. The report contains an in-depth analysis of causal and contributing factors associated with the measured results. A description of the clinical circumstances and a correction for case mix should be included to allow for a justified interpretation. The indicators must be part of an improvement strategy, for which comparison feedback is often used. We give examples of indicator development and applications in oncology, diabetes care, and the use of antibiotics for treating pneumonia. We explain how comparison with reference data can be used to construct improvement programmes.

Determinants of poor adherence in hypertensive patients: development and validation of the "Maastricht Utrecht Adherence in Hypertension (MUAH)-questionnaire"

OBJECTIVES

(1) To help identify patients with poor adherence and (2) to identify potential reasons that impede or facilitate adherence.

METHODS

Seventeen patients who used antihypertensive drugs participated in semi-standardized interviews. Interviews were recorded and reviewed by two investigators. Forty-four items were selected. An exploratory factor analysis was performed. Convergent validity was assessed by evaluating the association between sum scores on the identified subscales and three other adherence measures: (1) the Brief Medication Questionnaire (BMQ), (2) pharmacy refill records and (3) electronic monitoring. Regression analysis was used to evaluate the magnitude of associations.

RESULTS

Two hundred and fifty-five (90%) patients completed the questionnaire. Factor analysis resulted in a four-factor solution, explaining 30% of cumulative variance among respondents. The factors (scales) were labeled: positive attitude towards health care and medication (I), lack of discipline (II), aversion towards medication (III) and active coping with health problems (IV). Chronbach's alpha coefficient was 0.75, 0.80, 0.63 and 0.76 for scales I, II, III and IV, respectively. Convergent validity was partly supported by statistically significant associations that were found between sum scores of subscales 1 and II and the BMQ and electronic monitoring, respectively.

CONCLUSION

The MUAH-questionnaire has excellent psychometric properties and may be useful to identify factors that impede or facilitate adherence. However, it is not clear to what extent the questionnaire measures actual adherence.

PRACTICE IMPLICATIONS

Validation of the MUAH-questionnaire in other studies is needed.

A new molecular mechanism for severe myoclonic epilepsy of infancy: Exonic deletions in SCN1A

We examined cases of severe myoclonic epilepsy of infancy (SMEI) for exon deletions or duplications within the sodium channel SCN1A gene by multiplex ligation-dependent probe amplification. Two of 13 patients (15%) who fulfilled the strict clinical definition of SMEI but without SCN1A coding or splicing mutations had exonic deletions of SCN1A.