Biomedical subjects

Anna Modzelewska

Publications and source records attributed to Anna Modzelewska.

4 recordsLinked to original sources

PubMed2006

Arrestin interaction with rhodopsin: conceptual models.

It is becoming increasingly apparent that G protein-coupled receptors (GPCRs) can exist and function as oligomers. This notion differs from the classical view of signaling wherein the receptor has been presumed to be monomeric. Despite this shift in views, the interpretation of data related to GPCR function is still largely carried out within the framework of a monomeric receptor. Rhodopsin is a prototypical GPCR that initiates phototransduction. Like other GPCRs, the activity of rhodopsin is regulated by phosphorylation and the binding of arrestin. In the current investigation, we have explored by modeling methods the interaction of rhodopsin and arrestin under the assumption that either one or two rhodopsin molecules bind each arrestin molecule. The dimeric receptor framework may provide a more accurate representation of the system and is therefore likely to lead to a better and more accurate understanding of GPCR signaling.

Arrestins↗

PubMed2004

Rhodopsin signaling and organization in heterozygote rhodopsin knockout mice.

Rhodopsin (Rho) resides within internal membrane structures called disc membranes that are found in the rod outer segments (ROS) of photoreceptors in the retina. Rho expression is essential for formation of ROS, which are absent in knockout Rho-/- mice. ROS of mice heterozygous for the Rho gene deletion (Rho+/-) may have a lower Rho density than wild type (WT) membranes, or the ROS structure may be reduced in size due to lower Rho expression. Here, we present evidence that the smaller volume of ROS from heterozygous mice is most likely responsible for observed electrophysiological response differences. In Rho+/- mice as compared with age-matched WT mice, the length of ROS was shorter by 30-40%, and the average diameter of ROS was reduced by approximately 20%, as demonstrated by transmission and scanning electron microscopy. Together, the reduction of the volume of ROS was approximately 60% in Rho+/- mice. Rho content in the eyes was reduced by approximately 43% and 11-cis-retinal content in the eye was reduced by approximately 38%, as determined by UV-visible spectroscopy and retinoid analysis, respectively. Transmission electron microscopy of negatively stained disc membranes from Rho+/- mice indicated a typical morphology apart from the reduced size of disc diameter. Power spectra calculated from disc membrane regions on such electron micrographs displayed a diffuse ring at approximately 4.5 nm(-1), indicating paracrystallinity of Rho. Atomic force microscopy of WT and Rho+/- disc membranes revealed, in both cases, Rho organized in paracrystalline and raftlike structures. From these data, we conclude that the differences in physiological responses measured in WT and Rho+/- mice are due to structural changes of the whole ROS and not due to a lower density of Rho.

Animals↗

PubMedDate not supplied

[Selected markers of endothelial dysfunction in patients with subclinical and overt hyperthyroidism].

INTRODUCTION: There are many factors causing endothelial dysfunction. The aim was to observe chosen markers of endothelial function in patients with subclinical and overt hyperthyroidism. MATERIAL AND METHODS: We studied 97 patients with hyperthyroidism: 51 with subclinical (44 F/7 M; mean age 49.3 +/- 15.9 y) and 46 patients with overt (39 F/7 M, mean age 50.4 +/- 13.2 y). The control comprised of 39 healthy volunteers (26 F/13 M, mean age 47.5 +/- 11.8 y). Concentration of TSH, FT3, FT4 were measured by MEIA, TPO Ab, TG Ab, E-selectin, interleukin 6, VCAM-1, ICAM-1 by ELISA. RESULTS: The goiter was found in 71 persons 63F/8M, mean age 49.9 +/- 15.3 y, (42-subclinical, 29-overt). Morbus Graves-Basedow was diagnosed in 26 persons, 20 F/6 M, mean age 49.5 +/- 12.8 y (9-subclinical, 17-overt). There were no significant differences serum concentration of E-selectin, IL-6, ICAM-1 in patients with subclinical and overt hyperthyroidism compared to the control. Statistically significant differences were shown between concentration of IL-6 in patients with Graves-Basedow compared with the control (p < 0.05). Significance of VCAM-1 values were found in the patients with subclinical and overt hyperthyroidism compared to the control (p < 0.001; p < 0.001, respectively). CONCLUSIONS: Among persons with overt and subclinical hyperthyroidism occurs endothelial dysfunction which doesn't depends on exciting cause of thyrotoxicosis but on degree of hyperthyroidism. Elevated concentrations of endothelial markers may confirm that persons with thyroid disorders are extremely exposed to the occurrence of the cardiovascular diseases.

Adult↗

PubMedDate not supplied

[Markers of endothelial dysfunction in patients with iodine induced hyperthyroidism].

INTRODUCTION: It has been reported that hyperthyroidism is associated with an altered endothelial function and increased risk of arterial thromboembolism. The aim of our study was to estimate chosen markers of endothelial dysfunction in iodine-induced thyrotoxicosis (IIT). MATERIALS AND METHODS: The groups studied consisted of 41 hyperthyroid subjects, who had been treated with amiodarone (n = 6) or vitamin preparations supplemented with iodine (n = 35) and 40 persons with normal thyroid function. The following parameters were measured: thyroglobulin antibodies (TG Ab), thyroid peroxidase antibodies (TPO Ab), THS receptor antibodies (TR Ab), soluble adhesion molecules: sVCAM-1 and sICAM-1, von Willebrand factor (vWF), plasminogen activator inhibitor-1 (PAI-1), C-reactive protein (CRP), fibrinogen and urine iodine concentration. RESULTS: Patients with IIT had significantly higher levels of sVCAM-1 (p < 0.01), IL-6 (p < 0.005), fibrinogen (p < 0.005) and CRP (p < 0.05) in comparison to healthy subjects, whereas sICAM-1, PAI-1 and vWF concentrations did not differ between the groups studied. The highest sVCAM-1 levels were observed in patients with amiodarone induced thyrotoxicosis, and fibrinogen and CRP--in subjects receiving vitamin preparations. There were significant correlations between sVCAM-1 concentration and the levels of sICAM-1 (r = 0.341; p = 0.029) and PAI-1 (r = 0.347; p = 0.026), as well as with urine iodine concentration (r = 0.448; p = 0.004). IL-6 concentration correlated with vWF (r = 0.456; p = 0.003), TPO Ab (r = 0.328; p = 0.036) and PAI-1 level (r = 0.319; p = 0.042). CONCLUSION: Iodine induced thyrotoxicosis is associated with an increase of sVCAM-1 and IL-6 levels, possibly reflecting inflammatory and destructive processes in the thyroid gland. However, increased procoagulant activity was not found in patients with IIT.

Adult↗