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Secondary Phenomenon (secondary + phenomenon)

Distribution by Scientific Domains

Medical Sciences	75%

Selected Abstracts

Vascular regression is required for mesenchymal condensation and chondrogenesis in the developing limb

DEVELOPMENTAL DYNAMICS, Issue 3 2001
Melinda Yin
Abstract Vascular regression occurs during limb mesenchymal cell condensation and chondrogenesis, but it is unclear whether it is required for these processes or is a secondary phenomenon without major regulatory roles. To address this issue, beads presoaked with the potent angiogenic factor vascular endothelial growth factor (VEGF) were implanted in the vicinity of the prospective digit 2 in early chick embryo wing buds and the effects on angiogenesis and digit development were determined over time. We found that VEGF treatment caused a marked local increase in blood vessel number and density. Strikingly, this was accompanied by inhibition of digit 2 development as revealed by lack of expression of chondrogenic transcription factor Sox9 and absence of Alcian blue staining. Vascular distribution and skeletal development in adjacent areas remained largely unaffected. Inhibition of digit formation and excess vascularization were both reversible upon further embryonic growth and dissipation of VEGF activity. When supernumerary digits were induced at the anterior limb margin by retinoic acid treatment, their development was also preceded by vascular regression; interestingly, cotreatment with VEGF inhibited supernumerary digit development as well. Direct exposure of limb mesenchymal cells in micromass cultures to VEGF caused no obvious effects on condensation and chondrogenesis, indicating that VEGF effects are not due to direct action on skeletal cells. Our results are the first to provide evidence that vascular regression is required for mesenchymal condensation and chondrogenesis. A model of how patterning mechanisms and vascular regression may intersect and orchestrate limb skeletogenesis is proposed. © 2001 Wiley-Liss, Inc. [source]

Pregnancy-induced sympathetic overactivity: a precursor of preeclampsia,

EUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 6 2004
T. Fischer
Abstract Background, Preeclampsia has been shown to constitute a state of sympathetic overactivity. However, it remains unclear if the sympathetic activity precedes preeclampsia or represents only a secondary phenomenon. To further investigate this issue, we performed a prospective study in pregnant women considered to be at increased risk for preeclampsia owing to preeclampsia during a preceding pregnancy. Materials and methods, Twenty-two women with a history of preeclampsia were longitudinally studied on three occasions: twice during pregnancy (M1: 22 ± 4, M2: 33 ± 5 weeks) and once postpartum (M3: 26 ± 6 weeks postpartum). We measured muscle sympathetic nerve activity (MSNA), forearm blood flow, and blood pressure at rest and during reactive hyperaemia after forearm occlusion. Results, At M1 and M2, none of the subjects was hypertensive, however, muscle sympathetic nerve activity levels were significantly augmented, compared with their postpartum values (M1: 21 ± 9, M2: 29 ± 14, M3: 9 ± 5 bursts min,1; P < 0·05). Forearm vascular resistance did not significantly change from M1 through M3 (M1: 16 ± 9, M2: 15 ± 7, M3: 16 ± 7 U; P = NS). Gestational muscle sympathetic nerve activity values did not differ significantly among the subjects with subsequent preeclampsia compared with those who remained normotensive [with preeclampsia (n = 6): M1: 21 ± 5, M2: 27 ± 6, M3: 7 ± 4 bursts min,1; without preeclampsia (n = 16): M1: 21 ± 11, M2: 30 ± 16, M3: 9 ± 6 bursts min,1; P = NS]. Conclusion, Invariably, all women at risk for preeclampisa showed a pregnancy-induced increase in MSNA (pregnancy-induced sympathetic overactivity, PISO), which normalized after delivery. Most importantly, PISO is not necessarily associated with peripheral vasoconstriction and hypertension. Furthermore, only a subset of patients developed preeclampsia later on. Therefore, we hypothesize that PISO constitutes a precursor of preeclampsia which is physiologically compensated for by vasodilating mechanisms, leading to preeclampsia only when they fail. [source]

Anti- Saccharomyces Cerevisiae antibodies (ASCA), phenotypes of IBD, and intestinal permeability: A study in IBD families

INFLAMMATORY BOWEL DISEASES, Issue 1 2001
Severine Vermeire
Abstract Background Serologic markers anti- Saccharomyces cerevisiae antibodies (ASCA) and antineutrophil cytoplasmic antibodies with perinuclear staining (pANCA) have been proposed to study the immunopathogenesis of IBD. Their measurement may allow better phenotyping of the disease and the detection of subclinical disease. Aims To test the hypothesis that serological markers identify an immunologic trait related to disease susceptibility. We also wanted to test the hypothesis that ASCA is a marker related to abnormal tissue permeation by common antigens. Methods We studied the prevalence of pANCA and ASCA in a large cohort of sporadic and familial inflammatory bowel diseases and their unaffected relatives and spouses. Kinetics of ASCA was studied and the relationship between ASCA and 51Cr-EDTA intestinal permeation was investigated. Results ASCA was associated with sporadic Crohn's disease (CD) (63%), with Crohn's patients belonging to pure CD families (62%) and also with their unaffected family members (21%). pANCA was associated with UC (58%). The prevalence of ASCA in CD patients belonging to mixed families was strikingly low (33%). ASCA was a stable marker throughout the disease and was not related to an increased small intestinal permeability. Conclusion ASCA is strongly associated with familial CD in Belgium, and 21% of healthy family members also display the marker. The association is much weaker in patients belonging to mixed families. ASCA is a stable marker and is not a secondary phenomenon due to increased intestinal permeability. [source]

Does obstetric brachial plexus injury influence speech dominance?,

ANNALS OF NEUROLOGY, Issue 1 2009
Tibor Auer MD
Objective Right-handedness and left-sided language lateralization is an unresolved mystery with unknown cause/effect relations. Most studies suggest that the language lateralization is related to a fundamental brain asymmetry: right-handedness may be secondary. We analyzed the possibility of an opposite cause/effect relation: whether asymmetric hand usage (as a cause) can influence language lateralization (as a consequence). Methods We determined language lateralization by functional magnetic resonance imaging in 15 subjects whose upper limb (UL) had been injured at birth because of unilateral damage of the brachial plexus. These subjects were able to use only one (the noninjured) UL perfectly. Results We found correlation between the severity of right-sided UL injuries and hand usage dysfunction and the degree of left-to-right shift of language lateralization. There was, however, not a complete switch of language lateralization. Interpretation Right-sided UL injury can induce a left-to-right shift in language lateralization, suggesting that hand usage can influence language lateralization. These findings may contradict the broadly accepted theory that right-handedness is a secondary phenomenon caused by left-sided hemispheric language lateralization. However, the cause/effect problem between asymmetric hand usage and language lateralization is not resolved in this study. Our findings may support the theory that gestures had a crucial role in human language evolution and is a part of the language system even today. Ann Neurol 2009;65:57,66 [source]