Characterization of an immunologic polymorphism (D79H) in the heavy chain of factor V.

BACKGROUND: During the study of a family with hereditary factor (F)V deficiency (FV Amersfoort, 1102 A > T in exon 7) we identified an individual with 5% FV heavy chain antigen (FV(HC)) and 50% FV light chain antigen (FV(LC)). Further testing revealed that apart from the FV Amersfoort allele a second variant FV allele was segregating in this family, which encodes for a FV molecule with a reduced affinity for mAb V-23 used in the FV heavy chain ELISA (ELISA(HC)). OBJECTIVE: Identification and characterization of the molecular basis responsible for the reduced affinity of the variant FV for mAb V-23. METHODS: Family members of the proband were screened for mutations in the exons coding for the heavy chain of FV, after which the recombinant variant FV could be generated and characterized. Next, the cases and controls of the Leiden Thrombophilia Study (LETS) were genotyped for carriership of the variant FV. RESULTS: In the variant FV allele a polymorphism in exon 3 (409G > C) was identified, which predicts the replacement of aspartic acid 79 by histidin (D79H). Introduction of this mutation in recombinant FV confirmed that it reduces the affinity for binding to mAb V-23. The substitution has no effect on FV(a) stability and Xa-cofactor activity. In Caucasians the frequency of the FV-79H allele is approximately 5%. Analysis of the LETS revealed that the FV-79H allele is not associated with FV levels (FV(LC)), activated protein C sensitivity (using an activated partial thromboplastin time-based test) or risk of venous thrombosis (OR 1.07, CI 95: 0.7-1.7). CONCLUSION: The D79H substitution in FV should be considered as a neutral polymorphism. The monoclonal antibody V-23, which has a strongly reduced affinity for FV-79H, is not suitable for application in diagnostic tests.     

Coxsackievirus B1-based antibody-capture enzyme-linked immunosorbent assay for detection of immunoglobulin G (IgG), IgM, and IgA with broad specificity for enteroviruses.

An antibody-capture enzyme-linked immunosorbent assay (ELISA) with coxsackievirus B1 as the antigen was evaluated for detection of immunoglobulin G (IgG), IgM, and IgA antibodies and showed broad specificity for enteroviruses. In total, 116 serum or cerebrospinal fluid samples from 62 patients were tested by ELISA and the complement fixation test (CFT). Additionally, 15 serum samples that contained poliovirus-specific IgM antibody were tested. Serum samples from 200 healthy blood donors were used for standardization of the assays. The sensitivity of the ELISA varied with time of serum sampling, with a relatively low sensitivity when serum was collected within 3 days after the onset of symptoms (23%; 5 of 22) but good sensitivity when serum was collected later (83%; 20 of 24). The sensitivity was better than that of the CFT. The ELISAs were broadly reactive as concluded from typing of virus isolates that were simultaneously obtained. The assay did, furthermore, detect antibody against poliovirus type 3. Sera that contained rheumatoid factor, antinuclear antibody, or cardiolipin antibody (by the Venereal Disease Research Laboratory test) did not react in this ELISA. Nonspecific reactivity did occur, however, in cases of infectious mononucleosis and in Mycoplasma pneumoniae infection. The enterovirus-specific ELISA is found to be simple to perform, more sensitive than the CFT, and far less laborious than the neutralization test.     

Fulminant meningococcal septic shock in a boy with combined inherited properdin and protein C deficiency.

A 7-year-old patient with fulminant septic shock due to Neisseria meningitidis of the uncommon serogroup Y developed extensive gangrene of the limbs. Multiple amputations were necessary and a pulmonary embolism occurred within 2 days post-operatively. Complement and haemostatic system studies, done after recovery, showed a complete absence of properdin antigen and a low protein C antigen and activity level in plasma. Defective haemolytic activity in gel by the alternative pathway of complement activation could be restored with purified properdin, indicating a properdin deficiency type 1. Protein C antigen level as well as activity were in agreement with a protein C deficiency type I. The polymerase chain reaction (PCR) product of exon five of the protein C gene showed a substitution of 72Gly by Arg. Both deficiencies were traced among relatives of the patient. Serum of the father of the patient's mother was also properdin-deficient. Microsatellite haplotyping of the X-chromosome of the patient and his relatives showed that a distinct haplotype cosegregated with the properdin deficiency (Lodscore 2.25; four informative meioses). The protein C type I deficiency was present in the patient's mother and her mother and cosegregated with the mutation found. So far as is known, this is the first patient described with combined inherited properdin deficiency and protein C deficiency.     

Hereditary prothrombin deficiency presenting as intracranial haematoma in infancy

Hereditary deficiency of prothrombin is a rare autosomal recessive bleeding disorder, with severe bleeding diathesis in homozygotes, but rarely resulting in intracranial haematoma. We describe two infants of consanguineous parents, presenting with acute subdural haematoma. Because such haematomas in infancy are highly indicative of trauma caused by child battering and because the socio-economic status of the family was unstable, there was a suspicion of child battering. However, further investigations revealed a bleeding diathesis due to a prothrombin deficiency. DNA analysis of the prothrombin gene showed homozygosity for a novel mutation, substituting Lys for Glu at codon 7 and resulting in decreased specific clotting activity. We discuss the probability of bleeding diathesis versus child battering in the aetiology of intracranial haematoma.     

Simultaneous selection by object-based attention in visual and frontal cortex

Models of visual attention hold that top-down signals from frontal cortex influence information processing in visual cortex. It is unknown whether situations exist in which visual cortex actively participates in attentional selection. To investigate this question, we simultaneously recorded neuronal activity in the frontal eye fields (FEF) and primary visual cortex (V1) during a curve-tracing task in which attention shifts are object-based. We found that accurate performance was associated with similar latencies of attentional selection in both areas and that the latency in both areas increased if the task was made more difficult. The amplitude of the attentional signals in V1 saturated early during a trial, whereas these selection signals kept increasing for a longer time in FEF, until the moment of an eye movement, as if FEF integrated attentional signals present in early visual cortex. In erroneous trials, we observed an interareal latency difference because FEF selected the wrong curve before V1 and imposed its erroneous decision onto visual cortex. The neuronal activity in visual and frontal cortices was correlated across trials, and this trial-to-trial coupling was strongest for the attended curve. These results imply that selective attention relies on reciprocal interactions within a large network of areas that includes V1 and FEF.Visual scenes are usually too complex for all information to be analyzed at once. Selective attention selects a subset of the objects in the visual scene for detailed analysis at the expense of other items. Visual objects compete for selection, and the outcome of this competition depends on bottom-up cues such as saliency and perceptual organization and top-down cues that signal the objects’ behavioral relevance (1). It is not well understood how these different cues interact and which brain areas take the lead in visual selection.The top-down mechanisms for attentional selection are tightly linked to those for the selection of actions (2), and accordingly, cortical areas related to action planning influence the deployment of visual attention. The frontal eye fields (FEF) is one such area that is involved in visual processing, shifts of visual attention (2, 3), and also in the control of eye movements (4, 5). Area FEF contains different types of cells. Visual processing relies on visual and visuomovement cells, whereas the programming of eye movements relies on the activity of visuomovement and movement cells (6, 7). There are several lines of evidence that also implicate FEF in attentional control. First, FEF inactivation impairs attention shifts toward the contralateral visual field (8, 9). Second, subthreshold FEF microstimulation enhances neuronal activity in visual cortex in a manner that is reminiscent of selective attention (10, 11). Third, a role of FEF in the top-down guidance of attention is supported by studies on visual search. In search, selection signals in frontal cortex precede those in area V4 by 50 ms, suggesting that the frontal cortex determines selection and then provides feedback to visual cortex (12, 13). A comparable interareal delay in attentional effects was observed between the lateral intraparietal area and the motion sensitive middle temporal area (14). Thus, the parietal and frontal cortices appear to take the lead in attentional selection and to provide top-down signals to visual cortex. Within the visual cortex, such a reverse hierarchy (15) of attentional effects was observed in a task that required shifts of spatial attention (16) and also in a task demanding shifts between visual and auditory attention (17). Attentional signals in area V4 preceded signals in V2 by 50–250 ms, which in turn preceded attentional effects in the primary visual cortex (V1) by 50–400 ms.However, top-down factors are not the only ones that guide attention. Attention can be object-based, implying that the visual stimulus itself influences the distribution of attention too. If attention is directed to a feature, attention tends to coselect visually related features on the basis of perceptual grouping cues (18) so that entire objects rather than isolated features are attended (19, 20). The influence of perceptual grouping on attentional selection can be investigated with a curve-tracing task that requires grouping of the contour elements of a single curve (21, 22). Attention in this task is directed to the entire curve, implying that the curve’s shape itself influences the distribution of attention (22). Indeed, a traced curve evokes stronger activity in primary visual cortex than an irrelevant curve, revealing a neuronal correlate of object-based attention (23). However, it is not known if the coselection of all image elements of a single object is determined within early visual cortex or is guided by the frontal cortex, just as was shown for other tasks.Here we compare selection signals in areas FEF and V1 in the curve-tracing task with simultaneous recordings in the two areas. A priori, several possibilities exist for the interaction between V1 and FEF. First, the frontal cortex might select the relevant curve and then feed a guiding signal back to visual cortex (24, 25) as in the other tasks described above. If so, attentional selection signals in V1 might arise tens to hundreds of milliseconds later than in FEF. However, the chain of events in the curve-tracing task might differ because visual shape has a profound influence on the distribution of attention (26). Thus, a second possibility is that the visual cortex determines selection so that the attentional modulation in visual cortex precedes that in frontal cortex. A third possibility is that visual and frontal areas jointly determine what is relevant and what is not. In this situation, the selection signals are expected to occur in both areas at approximately the same time. It is also possible that the order of selection in different areas depends on the difficulty of the task. For example, the reverse hierarchy theory of visual perception (15) proposed that easy tasks are usually solved by higher visual areas, whereas lower visual areas are recruited when the picture has to be scrutinized. We therefore varied the difficulty of the curve-tracing task.     

Performance of cobas® 4800 and m2000 real-time™ assays for detection of Chlamydia trachomatis and Neisseria gonorrhoeae in rectal and self-collected vaginal specimen

A prospective, multicenter trial was designed to compare the performance characteristics of the cobas® 4800 (Roche Diagnostics, Indianapolis, IN, USA) and m2000 real-time™ (Abbott Molecular Inc., Des Plaines, IL, USA) assays for detection of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) in rectal and self-collected vaginal swabs. Rectal (n = 234) or self-collected vaginal swabs (n = 687) were obtained from consenting individuals visiting their general practitioners, dermatologists, gynecologists, sexually transmitted disease clinics, or family planning centers from May 2010 to February 2011. High concordance rates (≥96%) were observed between the cobas® 4800 and m2000 real-time™ assays for CT/NG detection in both rectal and self-collected vaginal swabs. The performance profiles confirm the usefulness of both kinds of swab types for CT and NG detection using described nucleic acid amplification tests assays. Based on this study, rectal and self-collected vaginal swabs offer a noninvasive alternative, which may improve screening for CT and NG infections.     

Depression in first generation labour migrants in Western Europe: the utility of the Center for Epidemiologic Studies Depression Scale (CES-D)

OBJECTIVE: The number of elderly migrants from Turkish and Moroccan descent in Western Europe will increase sharply in the coming decades. Identifying depressed elderly migrants necessitates a screening instrument that is both acceptable and has good psychometric properties. This study examines the utility of Turkish and Arabic translations of the Center for Epidemiologic Studies Depression Scale (CES-D) among elderly labour migrants from Turkish and Moroccan descent in the Netherlands. METHOD: The data were derived from a community based health survey among 304 native Dutch, 330 Turkish and 299 Moroccan migrants, aged 55-74 years, living in Amsterdam, the Netherlands. Acceptability, reliability, convergent and construct validity were studied. RESULTS: Acceptability of the CES-D was satisfactory, although Moroccan migrants and Turkish females had difficulty answering one or more of the (interpersonal) items from the CES-D. Translated versions of the CES-D proved to be highly internal consistent and have good convergent validity in both Turkish and Moroccan elderly. Depressed and somatic items were much more intermingled in Turkish and Moroccan elderly compared to earlier studies and native Dutch elderly. This fits to the hypothesis that Turkish and Moroccan elderly migrants tend to somatize their depressive symptoms much more than native Western elderly. CONCLUSION: The utility of the CES-D for elderly migrants of Turkish and Moroccan descent was found to be satisfactory.