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  • 1
    ISSN: 1432-0428
    Keywords: Keywords Diabetes, angiostatin, VEGF, bFGF, angiogenesis, retinopathy, cytokine, growth factors, photocoagulation, retina.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Aims/hypothesis. Proliferative diabetic retinopathy is a major debilitating disease causing most cases of blindness in humans in the Western world. Photocoagulation is the established therapy of proliferative diabetic retinopathy, although the molecular mechanisms of its effects are still not known. Recently angiostatin has been characterized as a potent inhibitor of neovascularization. Apart from a possible down-regulation of angiogenic cytokines, release of angiostatin could initiate the anti-angiogenic effects of retinal photocoagulation.¶Methods. We investigated the regulation of angiostatin and the angiogenic cytokines vascular endothelial growth factor and basic fibroblast growth factor in vivo by comparing vitreal concentrations of 18 control patients and 34 patients with proliferative diabetic retinopathy with and without previous photocoagulation. Concentrations of basic fibroblast growth factor and angiostatin were additionally measured in serum, while vascular endothelial growth factor is known to be regulated locally in the eye. Cytokines were measured by immunological methods.¶Results. Angiostatin could be detected in 2 out of 18 control patients and in 25 out of 34 diabetic patients (p 〈 0.00 001). Most importantly, production of angiostatin in human vitreous correlated significantly with previous retinal photocoagulation (p 〈 0.0001) in patients with proliferative diabetic retinopathy. Only two patients (one control and one diabetic) had detectable serum concentrations of angiostatin. Additionally patients with proliferative diabetic retinopathy and with previous photocoagulation had significantly lower concentrations of vascular endothelial growth factor (0.9 ± 0.1 ng/ml; p 〈 0.0001) than diabetic patients without previous photocoagulation (4.0 ± 0.8 ng/ml). The investigation of vitreal and serum basic fibroblast growth factor concentrations yielded no significant differences between the groups.¶Conclusion/interpretation. Angiostatin is not a regularly expressed angiogenesis inhibitor in human vitreous. The alterations we observed suggest that local release of angiostatin and down-regulation of vascular endothelial growth factor mediate the therapeutic effects of retinal photocoagulation in proliferative diabetic retinopathy. [Diabetologia (2000) 43: 1404–1407]
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0428
    Keywords: Keywords Insulin secretion, protein kinase, insulin secreting cells, human CaMK II, cloning of new subtypes.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Aims/hypothesis. The Ca2+/calmodulin-dependent protein kinase II (CaMK II) is highly expressed in pancreatic islets and associated with insulin secretion vesicles. The suppression of CaMK II disturbs insulin secretion and insulin gene expression. There are four isoforms of CaMK II, α to δ, that are expressed from different genes in mammals. Our aim was to identify the isoforms of CaMK II expressed in human beta cells by molecular cloning from a human insulinoma cDNA library and to assess its distribution in humans.¶Methods. The previously unknown complete coding sequences of human CaMK II β and the kinase domain of CaMK II δ were cloned from a human insulinoma cDNA library. Quantitative determination of CaMK II isoform mRNA was carried out in several tissues and beta cells purified by fluorescence activated cell sorting and compared to the housekeeping enzyme pyruvate dehydrogenase.¶Results. We found CaMK IIβ occurred in three splice variants and was highly expressed in endocrine tissues such as adrenals, pituitary and beta cells. Liver showed moderate expression but adipose tissue or lymphocytes had very low levels of CaMK II β-mRNA. In human beta cells CaMK II β and δ were expressed equally with pyruvate dehydrogenase whereas tenfold lower expression of CaMK II γ and no expression of CaMK IIα were found.¶Conclusion/interpretation. Although CaMK II δ is ubiquitously expressed, CaMK II β shows preferential expression in neuroendocrine tissues. In comparison with the expression of a key regulatory enzyme in glucose oxidation, pyruvate dehydrogenase, two of the four CaM kinases investigated are expressed at equally high levels, which supports an important role in beta-cell physiology. These results provide the basis for exploring the pathophysiological relevance of CaMK IIβ in human diabetes. [Diabetologia (2000) 43: 465–473]
    Type of Medium: Electronic Resource
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