[fMRI and DTI in delayed development of number processing]. / fMRT und DTI bei Entwicklungsverzögerung der Zahlenverarbeitung.

The neuronal correlate of the current cultural performance arose from developmental processes that can be observed by functional and anatomical magnetic resonance imaging. The velocity of these maturation processes occurs differently between adolescents, causing implications for both school career and academic performance. Regarding spatial-numerical cognition the myelinization of the superior longitudinal bundle appears to be crucial because this fiber connection intermediates between the linguistic nature of number words and conception of their spatial-numerical magnitude. The neuroscientific observation of anatomical brain maturation and its influence on school-relevant number processing may be helpful for educational purposes as well as for school psychology.

Absolute pulse energy measurements of soft x-rays at the Linac Coherent Light Source.

This paper reports novel measurements of x-ray optical radiation on an absolute scale from the intense and ultra-short radiation generated in the soft x-ray regime of a free electron laser. We give a brief description of the detection principle for radiation measurements which was specifically adapted for this photon energy range. We present data characterizing the soft x-ray instrument at the Linac Coherent Light Source (LCLS) with respect to the radiant power output and transmission by using an absolute detector temporarily placed at the downstream end of the instrument. This provides an estimation of the reflectivity of all x-ray optical elements in the beamline and provides the absolute photon number per bandwidth per pulse. This parameter is important for many experiments that need to understand the trade-offs between high energy resolution and high flux, such as experiments focused on studying materials via resonant processes. Furthermore, the results are compared with the LCLS diagnostic gas detectors to test the limits of linearity, and observations are reported on radiation contamination from spontaneous undulator radiation and higher harmonic content.

Evaluation of the stability of gentamicin in different antibiotic carriers using a validated MEKC method.

The quality control of gentamicin in different antibiotic carriers, using MEKC as stability-indicating method is described. Baseline separations of gentamicin C1, C1a, C2, C2a and C2b and, furthermore the impurities and degradation products garamin (GARA), 2-deoxy-streptamine (DSA) and sisomicin (SISO) were achieved with a background electrolyte containing 20mM deoxycholic acid, 15 mM beta-cyclodextrin and 100mM tetraborate (pH 10.0). After derivatization with o-phthaldialdehyde reagent (OPA), UV detection at 340 nm was possible. The method was validated with respect to selectivity, limit of detection (LOD) and quantification (LOQ) of the impurities, linearity, accuracy, precision and robustness. Evaluation of four different antibiotic carriers stored under stability conditions according to the International Conference on Harmonization (ICH) guidelines and older pharmaceutical formulations disclosed good stability.

Rapid identification of measles virus strains by the heteroduplex mobility assay.

The continued endemic presence of measles virus (MV), and the large number of isolates which are made in South Africa each year, demanded the use of a rapid and reliable pre-screening technique to select isolates for molecular epidemiological studies by sequence analysis. The heteroduplex mobility assay (HMA) was used to genetically characterize 47 MV isolates collected from three different provinces in South Africa, made between 1986 and 1995. The carboxyl-terminal 590 nt of the nucleocapsid (N) gene--the most variable region of the genome--was amplified by polymerase chain reaction (PCR) and subsequently subjected to HMA analysis for initial genotyping. The results showed three different patterns of heteroduplex formation by gel electrophoresis, representing two distinct wild-type lineages and one group of vaccine-like viruses. Comparison of HMA results with phylogenetic analysis of sequence data for several of the South African MV strains showed a complete correlation of results. The HMA proved to be a useful tool for screening MV isolates for use in molecular epidemiological studies.

Genotypic and antigenic characterization of hemagglutinin proteins of African measles virus isolates.

A comprehensive phylogenetic study based on the hemagglutinin (H) protein of all known African measles virus (MV) isolates is presented. The study includes 64 new H gene sequences from Ghana. Nigeria and South Africa as well as viruses from Zambia and The Gambia for which only incomplete sequencing data were available and that have previously not been genotyped. The results provide further support to the tentative assignment of the Nigerian and Ghanaian viruses to a new genotype B3 within clade B. A distinct geographic distribution pattern emerged with clade B viruses circulating exclusively in African countries north of the equator. All MV strains from southern Africa grouped in clades A and D with the majority of viruses belonging to genotype D4. The viruses considerably differed by their sensitivity to neutralization by monoclonal antibodies (mAb), but three selected antibodies were sufficient to distinguish between African MVs representing four different genotypes.

Placental transfer and decay of maternally acquired antimeasles antibodies in Nigerian children.

BACKGROUND: In developing countries vaccination against measles virus (MV) is generally administered at 9 months of age, although it is well-documented that protection of most infants by passively acquired maternal MV antibodies is waning before immunization is given. The purpose of this study was to investigate the decay of maternally derived MV antibodies in Nigerian infants as well as to compare a German and Nigerian cohort of paired mothers and newborns regarding the placental transfer efficiency of MV-specific IgG and total IgG antibodies. METHODS: MV-specific IgG antibodies were measured with a commercially available MV-enzyme-linked immunosorbent assay, a recombinant hemagglutinin enzyme-linked immunosorbent assay as well as a neutralization assay. Total IgG values were determined with a standard immunoturbidimetric test. RESULTS: Anti-MV IgG titers were twice as high in German newborns as in Nigerian newborns. An increased concentration of immunoglobulins transferred via the placenta was found only in the German cohort. High concentrations of total maternal IgG reduced the concentration of MV-specific as well as total IgG that crossed the placenta. Furthermore only 17% of the 4-month-old Nigerian infants were still protected against measles. Antibodies had a biologic half-life of 33 days and a biochemical half-life of 48 days. CONCLUSIONS: Our findings demonstrate that the decay of passively acquired MV antibodies occurred even more rapidly than expected resulting in susceptibility to MV in most of the 4-month-old infants in Nigeria. Furthermore transfer of maternal anti-MV IgG and total IgG antibodies to the newborn was more efficient in the German cohort compared with the Nigerian group. These findings suggest the use of alternative vaccination strategies in developing countries to possibly reduce the window of susceptibility against measles.

Isolation of measles virus from a naturally-immune, asymptomatically re-infected individual.

BACKGROUND: The changing epidemiology of measles with mild measles cases increasingly being recognised in previously-vaccinated individuals, suggests that more asymptomatic or subclinical cases might be occurring. Although this has been clearly documented in previously-vaccinated individuals, the frequency of these asymptomatic infections in individuals previously naturally-infected with measles is not known. Also, it is not known whether these asymptomatic or mildly-infected individuals who do not display the full range of clinical signs of measles are capable of transmitting the virus to other susceptible persons. OBJECTIVES: To demonstrate the isolation of measles virus (MV) from previously, naturally-immune individuals asymptomatically infected with measles while in close contact with acutely infected family members and to document the secondary immune responses (SIR) associated with asymptomatic measles infection. STUDY DESIGN: Throat swab and urine specimens from five acute measles cases and their family contacts, taken within 5 days of onset of rash in each acute case, were used to isolate MV by tissue culture. Positive tissue culture results were confirmed by indirect immunofluorescence (IF) staining. Measles specific antibodies (IgG and IgM), IgG urea avidity and measles-neutralising antibodies were measured in the one family (index family) where an asymptomatic measles infection of a contact was demonstrated. RESULTS: The acutely infected patient in the index family (T1/96) had a measles-neutralising antibody titre of < 1:10, measles IgG urea avidity of 24% and MV was isolated and confirmed by IF from urine and throat swab specimens. T1/96 represents acute measles infection after primary vaccine failure because he had a clear history of being vaccinated against measles as a child. MV was also successfully isolated from throat swab and urine specimens from the other four acute cases and from the urine but not the throat swab of an asymptomatically infected family contact in the index family (mother, T2/96). T2/96 had a history of natural measles infection as a child approximately 50 years ago. In addition to detectable MV in urine this contact also had a SIR with a rise in measles specific neutralising antibody titre. No virus was isolated from the other contact in the index family (father, T3/96) or from the contacts of the other four acute cases examined. CONCLUSIONS: This is the first report of a confirmed asymptomatic MV infection, by MV isolation and IF testing and a concurrent SIR, in a previously naturally-immune contact of an acute case. The importance of these findings to the epidemiology and control of MV as well as the diagnostic value of MV urine isolation and IF confirmation for mild or asymptomatic cases must be examined further.

Factors influencing student selection of family practice residency programs in Texas.

This study identified the relative influence of eight major factors on students' selections of family practice residency programs in Texas. All students (127) selected through the National Residency Matching Program in 1987 by 22 residency programs in Texas were surveyed. Based on a 91% response rate, 52 rating scale items were subjected to exploratory and confirmatory factor analyses. The resulting eight factors were rank ordered according to program type (eg, medical school based) based on mean scores of items that loaded on each factor. The factor most influential in students' selections of programs was the "quality of training" they perceived they would receive, while the least important factor was "resident compensation and benefits." Students who selected medical school based programs and community based, medical school affiliated programs differed significantly as to the importance they placed on the "academic orientation of the program" and the "attitude toward family physicians" in their program selections.

Skills for the beginning family medicine investigator.

The purpose of this study was to identify the necessary skills for a beginning researcher in family medicine, utilizing the views of those currently conducting research in the specialty. A Delphi study, involving three questionnaires, was conducted to determine skills needed in the following areas: designing a research project, conducting a research project, statistical knowledge and/or skills, and computer skills. Participants were 32 family physicians who had published at least one article in the Journal of Family Practice (1983-84) or Family Medicine (1983-84). The Delphi technique was successful in achieving consensus among study participants. A total of 77 skills were identified in the four areas as being at least somewhat important to the beginning family medicine investigator. Thirty-eight of these skills were identified as important to extremely important.

MiRNA-29: a microRNA family with tumor-suppressing and immune-modulating properties.

MicroRNAs (miRNAs) are ubiquitously expressed small, non-coding RNAs that negatively regulate gene expression at a post-transcriptional level. So far, over 1000 miRNAs have been identified in human cells and their diverse functions in normal cell homeostasis and many different diseases have been thoroughly investigated during the past decade. MiR-29, one of the most interesting miRNA families in humans to date, consists of three mature members miR-29a, miR-29b and miR-29c, which are encoded in two genetic clusters. Members of this family have been shown to be silenced or down-regulated in many different types of cancer and have subsequently been attributed predominantly tumor-suppressing properties, albeit exceptions have been described where miR-29s have tumor-promoting functions. MiR-29 targets expression of diverse proteins like collagens, transcription factors, methyltransferases and others, which may partake in abnormal migration, invasion or proliferation of cells and may favor development of cancer. Furthermore, members of the miR-29 family can be activated by interferon signaling, which suggests a role in the immune system and in host pathogen interactions, especially in response to viral infections. In this review, we summarize current knowledge on the genomic organization and regulation of the miR-29 family and we provide an overview of its implication in cancer suppression and promotion as well as in host immune responses. The numerous remarkable properties of these miRNAs and their often altered expression patterns might make the miR-29 family promising biomarkers and therapeutic targets for various diseases in future.

IL-24: physiological and supraphysiological effects on normal and malignant cells.

IL-24, previously known as melanoma differentiation antigen 7 (mda-7), is a member of the IL-10 family of cytokines and is mainly produced by Th2 cells and activated monocytes. Binding of IL-24 to either of its two heterodimeric receptors IL-20R1/IL-20R2 and IL-22R/IL-20R2 triggers phosphorylation and consequently activation of STAT3 and/or STAT1 in target tissues such as lung, testis, ovary, keratinocytes and skin. There is accumulating evidence that skin represents a major target tissue for IL-24 and related cytokines such as IL-19, -20, and -22. To date, the physiological properties of IL-24 are incompletely understood but available data indicate that it affects epidermal functions by increasing proliferation of dermal cells, suggestive of a possible role in psoriasis. However, the initial interest in IL-24 did not arise from its physiological signalling properties through its cognate receptors but rather because this cytokine has been reported to efficiently kill cancer cells independent of receptor expression and Jak-STAT signaling. These potentially intriguing properties have led to the development of adenovirally expressed IL-24, which was reported to induce selective cancer cell death in many different malignancies by activation or deactivation of a continuously growing list of distinct signaling pathways without harming surrounding healthy cells. In the present review we critically revisit and discuss the potential of IL-24 to become a selective and cancer cell-specific oncolytic drug and put these tentative properties into context with recent data on the physiological properties of this cytokine.

IL-24: a classic cytokine and/or a potential cure for cancer?

IL-24, a member of the IL-10 family of cytokines, is produced by monocytes and Th2 cells. Interestingly, immune cells do not appear to express specific IL-24 receptor chains (IL-20R1/IL-20R2 and IL-22R/IL-20R2), it is therefore unlikely that IL-24 has classical immune-modulating properties. Skin, on the other hand, seems to represent a major target tissue for IL-24 and related cytokines such as IL-19, -20, and -22. However, the initial interest in IL-24 did not arise from its physiological signalling properties through its cognate receptors but rather because of its tentative ability to selectively kill different cancer cells. In an attempt to further investigate the signalling events underlying the IL-24-induced cancer cell death, we found that melanoma cell lines did not react in the expected and previously described way. Using several different forms and delivery modes of IL-24, we were unable to detect any apoptosis-inducing properties of this cytokine in melanoma cells. In the present 'Point of view' we will briefly summarize these findings and put them in context of published reports stating that IL-24 might be a long sought after treatment for several types of cancer.

Regional differentiation of gastric and of pyloric smooth muscle in the pig: mechanical responses to acetylcholine, histamine, substance P, noradrenaline and adrenaline.

1. Mechanical activity was recorded in isolated muscle preparations from the circular and longitudinal layers of different regions of porcine stomach and from the pyloric ring. 2. In all gastric strips acetylcholine (10(-7)-10(-4) mol l-1), histamine (10(-7)-10(-5) mol l-1) and substance P (10(-9)-10(-7) mol l-1) elicited contractions. 3. In fundic strips the catecholamines, noradrenaline and adrenaline (10(-8)-10(-5) mol l-1), produced inhibitory responses at lower concentrations and excitatory responses at high concentrations. After blockade of beta-adrenoceptors by propranolol, a pure excitatory response remained which could be inhibited by alpha-adrenoceptor blockade with phentolamine. No responses were observed in corpus and antrum. 4. Strong contractions were induced by these catecholamines in circular muscle strips of the pyloric ring, in contrast to previous findings reported for human and canine preparations. The contractile response of strips from the inner layer of the pyloric ring corresponded to an average shortening of 25-30% of resting length, at a concentration of 10(-5) mol l-1 of noradrenaline or adrenaline. The responses of preparations from the outer layer of the pyloric ring were similar to those of the inner layer but generally weaker. The excitatory responses to the catecholamines were totally suppressed by 10(-5) mol l-1 phentolamine or prazosin but remained unaltered after pretreatment with 10(-5) mol l-1 propranolol or 10(-6) mol l-1 yohimbine, which indicates that they are mediated by alpha 1-adrenoceptors. 5. Application of substance P (10(-7) mol l-1) in the pyloric preparations caused a contraction as strong as that induced by noradrenaline or adrenaline. However, histamine, which is known to induce strong contractions in canine pylorus, had--as in human pylorus--no effect on porcine pylorus at concentrations up to 10(-5) mol l-1.

Sequence analysis of the nucleocapsid gene of measles virus isolates from South Africa identifies a new genotype.

Sequence analysis was performed on 20 measles virus (MV) isolates from South Africa, five of which were obtained between 1986 and 1989 and 15 isolates collected during the 1994/95 measles season. A 590 bp fragment of the carboxyl terminus of the nucleocapsid (N) was amplified by PCR and subjected to sequence and phylogenetic analysis. Comparison of the South African MV strains with those previously described revealed that at least two distinct groups of wild-type (wt) MV exist, one of which has been circulating since 1986. The major genotype (I) was represented by the more recent isolates which showed three characteristic amino acid substitutions. Furthermore, three vaccine-like viruses with sequences very similar to the Edmonston wt strain were identified. Phylogenetic analysis of 100 MV strains allowed the assignment of new definitions for MV genotypes and subgroups. Employing these definitions, the majority of South African isolates analysed here formed a new genotype.

Partial amplification of the measles virus nucleocapsid gene from stored sera and cerebrospinal fluids for molecular epidemiological studies.

The analysis of stored sera for retrospective molecular epidemiological studies provides a powerful tool to investigate strain variation in measles viruses that had circulated up to 20 years ago. For this purpose, a rapid and simple method for extraction of RNA from stored sera and cerebrospinal fluids (CSF) was developed. When used on sera and CSFs that have been frozen for as long as 20 years, this method proved to be more efficient than established techniques. The extracted RNA was reverse transcribed into cDNA by using random hexamer primers. The PCR amplification of the 3' terminus of the nucleocapsid gene (N) was divided into two overlapping fragments of 375 and 384 bp length, covering the entire region of interest. This region is thought to have the highest variability within the MV genome and has previously been shown to be suitable for strain characterization. The resulting PCR fragments were sequenced manually by using standard methods without the need of further clean-up steps.

Heteroduplex mobility assay (HMA) pre-screening: an improved strategy for the rapid identification of inserts selected from phage-displayed peptide libraries.

Phage-displayed peptide libraries represent an efficient tool to isolate peptides that bind a given target molecule. After several selection rounds, generally a large pool of target binding phages is obtained. Conventional analysis of the selected phage population involves extensive sequencing of many clones, most of which can be identical. We have adapted the Heteroduplex Mobility Assay (HMA) for pre-screening of phage inserts that were amplified by direct colony PCR of ELISA-positive clones. This strategy allowed for the rapid and reproducible assignment of insert sequences to different 'heteroduplex migration groups'. Sequence analysis of only one representative of each HMA migration group then completes the characterisation of the binding phage population. In our model experiments, only 16% of HMA pre-screened clones required further sequence analysis.

Case report and molecular analysis of subacute sclerosing panencephalitis in a South African Child.

This is the first case of subacute sclerosing panencephalitis from South Africa in which the molecular characteristics of the causative measles virus were examined. The virus found is classified as genotype D3, which has not previously been found in Africa and was last circulating in the United States before 1992.