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Biomedical subjects

M Baron

Publications and source records attributed to M Baron.

At least 55 records · Page 3Linked to original sources
PubMed2000

Multiple roles of the Dcdc42 GTPase during wing development in Drosophila melanogaster.

The Rho sub-family of GTPases, comprising Rho, Rac and Cdc42. regulates many biological processes, including morphogenesis, cell polarity, migration, the cell cycle and gene expression. It is important to develop genetic approaches to allow the dissection, in vivo, of the mechanisms of GTPase regulation and signal transmission, and their biological consequences. In this regard, wing development in Drosophila melanogaster is an excellent model system. To investigate the functions of the Drosophila Cdc42 GTPase (Dcdc42), we generated phenotypes during wing development, by expression of the dominant-negative N17 and L89 mutants of Dcdc42. We have identified roles for Dcdc42 in wing growth, and in cell fate choice during the development of the wing veins and the peripheral nervous system. Reduction of Dcdc42 signalling following over-expression of Dcdc42N17 resulted in a broader but more diffuse domain characterised by wing-margin sensory bristles. This was correlated with a broadened stripe of wingless expression along the dorsal-ventral boundary of third-instar wing imaginal discs. Together with genetic interactions with loss- and gain-of-function Notch alleles, these data support a role for wild-type Dcdc42 as a negative regulator of Notch signalling.

Animals↗
PubMed2000

Antigastric autoantibodies in Helicobacter pylori infection: role in gastric mucosal inflammation.

UNLABELLED: The aim of the study was to ascertain whether there is an association between the presence of serum parietal cell autoantibodies (PCA) and: (1) Helicobacter pylori infection; (2) the presence and degree of gastritis and intestinal metaplasia; and (3) the H. pylori infecting strain. Gastric mucosal biopsies were obtained from 49 consecutive patients in order to assess and grade gastritis, make a histological diagnosis, and culture and genotype H. pylori. H. pylori infection was present in 26 patients (group 1), had been present in 17 patients (group 2), and the remaining 6 (group 3) had never had the infection. The infecting strain was cagA positive in 21 of 26 group 1 patients. Positive PCA results were found in 84%, 76%, and 14% of patients in groups 1, 2, and 3, respectively. PCA results were correlated with anti-H. pylori antibody titers (P<0.05). In group 2 patients, PCA were associated with the degree of antral gastritis (Fisher's exact test P<0.05). cagA status was not associated with the presence of PCA (chi2=0.68, NS). The frequency of positive findings for PCA in group 2 was higher in patients with (90%) than in those without (50%) intestinal metaplasia. IN CONCLUSION: (1) H. pylori infection is associated with the production of PCA, which, after eradication of the infection, persist and might contribute to the persistent antral chronic gastritis and intestinal metaplasia; (2) the gastric lesions associated with infections sustained by the more-virulent H. pylori strains do not appear to be due to the induction of antigastric autoantibodies.

Adolescent↗
PubMed2000

Identification of genomic regions that interact with a viable allele of the Drosophila protein tyrosine phosphatase corkscrew.

Signaling by receptor tyrosine kinases (RTKs) is critical for a multitude of developmental decisions and processes. Among the molecules known to transduce the RTK-generated signal is the nonreceptor protein tyrosine phosphatase Corkscrew (Csw). Previously, Csw has been demonstrated to function throughout the Drosophila life cycle and, among the RTKs tested, Csw is essential in the Torso, Sevenless, EGF, and Breathless/FGF RTK pathways. While the biochemical function of Csw remains to be unambiguously elucidated, current evidence suggests that Csw plays more than one role during transduction of the RTK signal and, further, the molecular mechanism of Csw function differs depending upon the RTK in question. The isolation and characterization of a new, spontaneously arising, viable allele of csw, csw(lf), has allowed us to undertake a genetic approach to identify loci required for Csw function. The rough eye and wing vein gap phenotypes exhibited by adult flies homo- or hemizygous for csw(lf) has provided a sensitized background from which we have screened a collection of second and third chromosome deficiencies to identify 33 intervals that enhance and 21 intervals that suppress these phenotypes. We have identified intervals encoding known positive mediators of RTK signaling, e.g., drk, dos, Egfr, E(Egfr)B56, pnt, Ras1, rolled/MAPK, sina, spen, Src64B, Star, Su(Raf)3C, and vein, as well as known negative mediators of RTK signaling, e.g., aos, ed, net, Src42A, sty, and su(ve). Of particular interest are the 5 lethal enhancing intervals and 14 suppressing intervals for which no candidate genes have been identified.

Alleles↗
PubMed2000

The mother-child interaction and clinical judgment during acute pediatric illnesses.

OBJECTIVES: For acutely ill children living in less than optimal environments, mothers and pediatricians may have a heightened perception of illness severity, a lower specificity of clinical judgments, and a tendency to over-utilize resources. We examined the mother-child interaction in order to understand the relation of less optimal environments to clinical judgment and resource use. STUDY DESIGN: At the 2-week and 6-, 15-, and 24-month well child visits of 316 children, the mother-well child interaction was assessed by using the Biringen's Emotional Availability Scales (EAS). Data were gathered regarding maternal depression and sense of competence, infant temperament, maternal social support, life events, the home environment, and demographics. At ill visits, the mother-ill child interaction was assessed by using the EAS, and mothers and pediatricians independently assessed illness severity using the Acute Illness Observation Scales. Resource use during the illness was evaluated. RESULTS: One thousand nine hundred eight-three acute illnesses were assessed. A less optimal mother-child interaction was significantly (P <.05 for all comparisons) associated with poorer reliability of mothers' judgments, lower specificity of mothers' judgments (71% vs 85%) and pediatricians' judgments (92% vs 97%), and greater use of resources (eg, for hospitalizations, 2.6% of visits vs 0.7%). Adverse maternal, infant, and demographic characteristics were associated with a less optimal mother-well child (r = 0.68) and mother-ill child (r = 0.80) interaction, a heightened perception of illness severity, and greater resource use. CONCLUSION: Less optimal environments adversely affect the mother-child interaction; a poor mother-child interaction is correlated with low specificity of clinical judgment and over-utilization of resources.

Acute Disease↗
PubMed2000

[Sonographic findings of acardiac twin in the first trimester of pregnancy].

Twin Reversed Arterial Perfusion (TRAP) sequence, or the acardiac anomaly, is a rare complication of monozygotic twins, that occurs in approximately 1 in 35,000 births. In the first trimester, once the diagnosis of monochorionic twins is made, particularly if one embryo shows abnormal development or generalized edema, the TRAP sequence must be considered. Moreover, malformations reported in the perfused twin are often severe. Diagnosis is confirmed by using Doppler ultrasound which demonstrated the presence of retrograde perfusion in the umbilical cord of the abnormal twin. The more complete the body form is, the more similarity the vascular relationships have to the pattern found in a full-term fetus. Final outcome and treatment decisions can be determined based on hemodynamic criteria. We report a case of a misdiagnosed TRAP sequence with no structural malformations detected by ultrasonography at 12 weeks of gestation.

Adult↗
PubMed1999

Characterization of the human glutamate receptor subunit 3 gene (GRIA3), a candidate for bipolar disorder and nonspecific X-linked mental retardation.

The X-chromosome breakpoint in a female patient with a balanced translocation t(X;12)(q24;q15), bipolar affective disorder and mental retardation was mapped within the glutamate receptor 3 (GRIA3) gene by fluorescence in situ hybridization. The GRIA3 cDNA of 5894 bp was cloned, and the gene structure and pattern of expression were determined. The most abundant GRIA3 transcript is composed of 17 exons. An additional 5 exons (2a, 2b, 5a, 5b, and 5c) from the 5' end of the GRIA3 open reading frame were identified by EST analysis (ESTs AI379066 and AA947914). Two new polymorphic microsatellite repeats, (TC)(n=12-26) and (AC)(n=15-19), were identified within GRIA3 5' and 3'UTRs. No mutations were detected in families segregating disorders mapping across GRIA3, one with X-linked bipolar affective disorder (BP) and one with a nonspecific X-linked mental retardation (MRX27). To assess the possibility of the involvement of the GRIA3 gene in familial cases of complex BP, a large set of 373 individuals from 40 pedigrees segregating BP were genotyped using closely linked (DXS1001) and intragenic (DXS1212 and GRIA3 3' UTR (AC)(n))) GRIA3 STR markers. No evidence of linkage was found by parametric Lod score analysis (the highest Lod score was 0. 3 at DXS1212, using the dominant transmission model) or by affected sib-pair analysis.

Adult↗
PubMed1999

The specificity of a weak gamma delta TCR interaction can be modulated by the glycosylation of the ligand.

The gamma delta T cell clone LBK5 recognizes the MHC molecule IEk. Here, we demonstrate that the affinity of this interaction is weaker than those typically reported for alpha beta TCRs that recognize peptide/MHC complexes. Consistent with our previous finding that peptide bound to the IE molecule does not confer specificity, we show that the entire epitope for LBK5 is contained within the polypeptide chains of the molecule, centered around the polymorphic residues 67 and 70 of the IE beta-chain. However, LBK5 recognition is profoundly influenced by the N-linked glycosylation at residue 82 of the IE alpha-chain. Since infected, stressed, or transformed cells often change the posttranslational modifications of their surface glycoproteins, this finding suggests a new way in which gamma delta T cell Ag recognition can be regulated.

Animals↗
PubMed1999

The needs of patients with arthritis: the patient's perspective.

OBJECTIVE: To identify concerns and learning interests of patients with arthritis. METHODS: A questionnaire was developed, pilot tested, and then used to evaluate 197 patients with arthritis, including osteoarthritis (OA) (n = 41), rheumatoid arthritis (RA) (n = 57), back disease (n = 55), systemic lupus erythematosus (n = 27), and systemic sclerosis (SSc) (n = 17). Twenty concerns and 12 learning interests were rated. Questionnaires were also administered to assess physical disability (Health Assessment Questionnaire), psychological disability (Arthritis Impact Measurement Scales 2), and pain (visual analog scale). Participants addressed accessibility of health services, satisfaction with their physician, psychosocial needs, use of self-help groups, and behavioral strategies used to assist coping. Patients with RA, OA, and back disease, at both a community and a hospital center, were tested to assess whether concerns and learning interests differed based on site of treatment. Analytic methods included analysis of variance, factor analysis, and multiple linear regression. RESULTS: There were no differences in concerns or learning interests based on treatment site. Between diagnostic groups, patients with SSc were more interested in learning about self-help groups. The most frequently reported concern was worsening of the illness. The majority of respondents were interested in learning more about topics that were illness specific. The physician was chosen as the preferred source of information, and the preferred format was in writing. On factor analysis, the 20 concerns were reduced to 5 factors: psychological, coping, medication, social, and financial. Three factors were identified for learning interests: the illness, traditional health management topics, and nontraditional health management topics. Stepwise multiple linear regression revealed predictors for the 5 concern and 3 learning interest factors. The concerns were best predicted by self-reported disease severity, physical disability, and psychological distress, while learning interests were best predicted by self-reported disease severity, pain, and self-help group membership. CONCLUSION: Concerns and learning interests of persons with arthritis did not differ based on the center of treatment or the diagnosis, but can be predicted by the level of pain and simple measures of disability. Better understanding of the relationship between health status and patient-perceived needs will result in improved patient-centered care.

Activities of Daily Living↗
PubMed1999

A comprehensive linkage analysis of chromosome 21q22 supports prior evidence for a putative bipolar affective disorder locus.

Previously, we demonstrated evidence of linkage to bipolar affective disorder (BP) in a single large, multigenerational family with a LOD score of 3.41 at the PFKL locus on chromosome 21q22.3. Additional families showed little support for linkage to PFKL under homogeneity or heterogeneity, in that study. We have expanded on that analysis, with 31 microsatellite markers at an average marker spacing of </=2 cM, in the largest multigenerational BP pedigree series reported to date. A two-point heterogeneity (alpha=0.5) LOD score of 3.35 (P<.000156) was found at the D21S1260 locus, 5 cM proximal to PFKL. Polylocus analysis with a cluster of three neighboring markers was consistent with these results (PL-HetLOD = 3.25). In the design of this study, 373 individuals from 40 families (from a total set of 1,508 individuals in 57 families) were chosen, as a cost-effective approach to genotyping this large sample set. Linkage analyses were performed with an "affecteds-only" method. As such, our results are based solely on genetic information from affected individuals, without assumptions about the disease-locus genotypes of the unaffecteds. Furthermore, for ease of comparison, this study was performed with the same approach as a 10-cM genome scan for BP loci, the results of which will be reported elsewhere.

Bipolar Disorder↗
PubMed1999

The Drosophila melanogaster Suppressor of deltex gene, a regulator of the Notch receptor signaling pathway, is an E3 class ubiquitin ligase.

During development, the Notch receptor regulates many cell fate decisions by a signaling pathway that has been conserved during evolution. One positive regulator of Notch is Deltex, a cytoplasmic, zinc finger domain protein, which binds to the intracellular domain of Notch. Phenotypes resulting from mutations in deltex resemble loss-of-function Notch phenotypes and are suppressed by the mutation Suppressor of deltex [Su(dx)]. Homozygous Su(dx) mutations result in wing-vein phenotypes and interact genetically with Notch pathway genes. We have previously defined Su(dx) genetically as a negative regulator of Notch signaling. Here we present the molecular identification of the Su(dx) gene product. Su(dx) belongs to a family of E3 ubiquitin ligase proteins containing membrane-targeting C2 domains and WW domains that mediate protein-protein interactions through recognition of proline-rich peptide sequences. We have identified a seven-codon deletion in a Su(dx) mutant allele and we show that expression of Su(dx) cDNA rescues Su(dx) mutant phenotypes. Overexpression of Su(dx) also results in ectopic vein differentiation, wing margin loss, and wing growth phenotypes and enhances the phenotypes of loss-of-function mutations in Notch, evidence that supports the conclusion that Su(dx) has a role in the downregulation of Notch signaling.

Amino Acid Sequence↗