Biomedical subjects

Mirna Saraga-Babić

Publications and source records attributed to Mirna Saraga-Babić.

9 recordsLinked to original sources

PubMed2006

Immunohistochemical study of cytoskeletal and extracellular matrix components in the notochord and notochordal sheath of amphioxus.

A major cytoskeletal and extracellular matrix proteins of the amphioxus notochordal cells and sheath were detected by immunohistochemical techniques. The three-layered amphioxus notochordal sheath strongly expressed fish collagen type I in its outer and middle layers, while in the innermost layer expression did not occur. The amphioxus notochordal sheath was reactive to applied anti-human antibodies for intermediate filament proteins such as cytokeratins, desmin and vimentin, as well as to microtubule components (beta-tubulin), particularly in the area close to the epipharyngeal groove. Alpha-smooth muscle actin was expressed in some notochordal cells and in the area of the notochordal attachment to the sheath. Thus muscular nature of notochordal cells was shown by immunohistochemistry in tissue section. Our results confirm that genes encoding intermediate filament proteins, microtubules and microfilaments are highly conserved during evolution. Collagen type I was proven to be the key extracellular matrix protein that forms the amphioxus notochordal sheath.

Actin Cytoskeleton↗

PubMed2006

Involvement of cytoskeletal proteins and growth factor receptors during development of the human eye.

The spatial and temporal distribution of nestin, cytokeratins (CKs), vimentin, glial fibrillary acidic protein (GFAP), neurofilaments (NFs), beta-tubulin as well as fibroblast growth factor receptors (FGFRs) and platelet-derived growth factor receptor beta (PDGF-Rbeta) were investigated in the developing human eye in eight conceptuses of 5-9 postovulatory weeks using immunostaining. Nestin was found in the neuroglial precursors and the radial glial fibres of the optic nerve. In the pigmented retina, nestin was present only in the 5th week, while at later stages (6-9th week), co-expression of CKs and vimentin was seen. Nestin, CKs, vimentin, and GFAP were observed in the precursors to various cell types in the neural retina. Additionally, their expression was also apparent in the lens epithelium, showing its gradual fading following the lens fibre elongation. They appeared in the mesenchymal cells of the cornea, the choroid, the sclera, and the corpus vitreum, too. In the corneal epithelium, co-expression of nestin and CKs was detected. NFs and beta-tubulin were confined to the differentiating retinal neuroblasts. Growth factor receptors were seen in the retina, the lens epithelium while less intensely in the lens fibres, the corneal epithelium, and the mesenchymal cells. During the early eye development (5-9th week), IFs expressing normal pattern of distribution as well as acting in concert might contribute to the normal developmental processes occurring in certain parts of the human eye. Additionally, NFs and beta-tubulin seem to have an important role in the retinal ganglion cell differentiation, while FGFRs and PDGF-Rbeta may regulate the cell proliferation, differentiation, and survival in various parts of the developing eye.

Cytoskeletal Proteins↗

PubMed2006

Role of mitotic, pro-apoptotic and anti-apoptotic factors in human kidney development.

The expression pattern of mitotic Ki-67 and anti-apoptotic bcl-2 proteins, as well as apoptotic caspase-3 and p53 proteins, were investigated in the human mesonephros and metanephros of 5-9 week-old human conceptuses. Apoptotic cells were additionally detected using the terminal deoxynucleotidyl transferase (TdT) nick-end labelling (TUNEL) method. Between the 5th and 7th developmental weeks Ki-67, caspase-3 and TUNEL-positive cells characterized all mesonephric structures, indicating importance of cell proliferation in the growth of the mesonephros and role of apoptosis in nephrogenesis. From the 7th week on, p53 and bcl-2 positive cells appeared in the mesonephros as well. Regressive changes in the mesonephros could be regulated by activation of p53, while bcl-2 could contribute to selective survival of some tubules giving rise to adult structures. In the early human metanephros (5-7 weeks), Ki-67 positive cells characterized all metanephric structures, indicating a role of cell proliferation in branching of the ureteric bud and in nephron formation. During the same period bcl-2, caspase-3 and TUNEL-positive cells were found only in the metanephric mesenchyme and nephrons. Bcl-2 protein probably protected nephrons from apoptosis, while caspase-3 protein controlled cell death in the mesenchyme. At later stages (7-9-weeks), appearance of p53-expressing cells could participate in further morphogenesis of the metanephric collecting system. The factors investigated had a spatially and temporally restricted pattern of appearance in developing kidneys. Changes in that pattern might lead to serious disturbances of kidney formation and function in early childhood.

Apoptosis↗

PubMed2006

The notochordal sheath in amphioxus--an ultrastructural and histochemical study.

The notochord and notochordal sheath of 10 adult amphioxus were investigated ultrastructurally and histochemically. The notochord in amphioxus consists of parallel notochordal cells (plates) and each plate consists of parallel thicker and thinner fibrils and numerous profiles of smooth endoplasmic reticulum situated just beneath the cell membrane. Histochemical staining shows that the notochordal plates resemble neither the connective tissue notochordal sheath nor the typical muscular structure myotomes. The notochordal sheath has a complex three-layered organization with the outer, middle and inner layer The outer and middle layer are composed of collagen fibers of different thickness and course, that correspond to collagen type I and collagen type III in vertebrates, respectively, and the inner layer is amorphous, resembles basal lamina, and is closely attached to the notochord by hemidesmosome junctions. These results confirm the presence of collagen fibers and absence of elastic fibers in amphioxus.

Animals↗

PubMed2005

Cell death in developing human spinal cord.

Cell death in the developing human spinal cord was investigated in 5-12 week human conceptuses using immunohistochemical and TUNEL methods. Expression of pro-apoptotic (Fas-receptor, caspase-3) and anti-apoptotic (bcl-2) markers and marker for internucleosomal fragmentation (TUNEL) were analysed in the cranial and caudal parts of the human spinal cord. In early developmental stages (5-6 weeks) of the cranial spinal cord, bcl-2 positive cells were seen in the ventricular zone and in the roof plate, while in the caudal part they were seen surrounding the central lumen. Subsequently, bcl-2 expression appeared in the basal plates of the grey matter and in the spinal ganglia, and from the seventh week on they also appeared in the intermediate horn of the grey matter. In the fetal period, bcl-2 expression appeared in the dorsal horns of the grey matter (9 weeks) but ceased in the ventricular zone (12 weeks) . In the trunk region, TUNEL-positive cells were found in ventricular and mantle zones along the whole length of the spinal cord. Caspase-3 positive cells and Fas-receptor positive cells appeared only in the grey matter of the cranial segments (head and trunk) of the spinal cord, but they were missing in the caudal parts. Caspase-3 dependant pathway, probably activated by Fas-receptor, seems to operate only in the cranial part of the human spinal cord. In the caudal (sacrococcygeal and tail) parts, cells seem to die by caspase-3 independent pathway. The interplay of pro-apoptotic and anti-apoptotic factors may be associated with cranial spinal cord morphogenesis, adjustment of cells number and selective survival of neurons, while in the caudal regions these factors cause massive cell death associated with regression of the caudal spinal cord.

Apoptosis↗

PubMed2005

Apoptosis and active caspase-3 expression in human granulosa cells.

OBJECTIVE: To document the expression of activated forms of caspase-3 in human granulosa cells. DESIGN: Laboratory study. SETTING: In vitro fertilization (IVF) laboratory of the Split University Hospital and laboratory of the Department of Anatomy, Histology, and Embryology. PATIENT(S): Ovarian tissues were obtained from women undergoing hysterectomy/ovariectomy for benign conditions and human granulosa cells were obtained from women undergoing oocyte retrieval for IVF. INTERVENTION(S): Immunostaining of tissue sections and cell smears using antibody to active caspase-3 and terminal deoxynucleotidyl transferase (TdT) assay (TUNEL) for detection of internucleosomal DNA fragmentation. MAIN OUTCOME MEASURE(S): Microscopic evaluation to assess the presence and cellular co-localization of active caspase-3 and TUNEL-positive cells. RESULT(S): In human ovarian tissue, no apoptosis was observed in primordial and primary follicles. Apoptosis in granulosa cells was detected only in atretic antral follicles. Granulosa cells classified as apoptotic on the basis of their morphologic features contained a single condensed nucleus, multiple nuclear fragments, or apoptotic bodies. All apoptotic granulosa cells expressed active caspase-3, but only few contained fragmented DNA detected with the TUNEL method. The expression of active caspase-3 was also demonstrated in human granulosa cells of preovulatory follicles obtained from patients undergoing IVF. CONCLUSION(S): Caspase-3 dependent apoptosis occurs in human granulosa cells and activates when follicles begin to leave the resting pool. After initial formation of the antrum, activation of caspase-3 is a normal physiologic process of the follicle during atresia and luteinization. Higher numbers of granulosa cells positive with caspase-3 than cells positive with TUNEL suggest an earlier activation of caspase-3 compared with the DNA fragmentation detected by TUNEL assay and also a longer detection period of caspase-3 than DNA fragmentation in apoptotic granulosa cells.

Adult↗

PubMed2004

Cell proliferation during the early stages of human eye development.

The distribution as well as the ultrastructural and biochemical characteristics of proliferating cells in the human eye were investigated in five conceptuses of 5-9 postovulatory weeks, using morphological techniques and Ki-67 immunostaining. The Ki-67 nuclear protein was used as a proliferation marker because of its expression in all phases of the cell cycle except the resting phase (G0). The labelling indices of Ki-67-positive cells were analysed by means of the Kruskal-Wallis ANOVA test and the Wilcoxon matched-pairs test. In the 5th week, mitotic cells were the most numerous between the two layers of the optic cup, the optic cup and stalk, and between the lens pit and the surface ectoderm. During the 6th week, cells were observed in the lens epithelium covering the whole cavity of the lens vesicle as well as in the neuroblast zone and the pigmented epithelium of the retina. At later stages (7th-9th weeks), Ki-67-positive cells were restricted to the anterior lens epithelium, the outer neuroblast zone, and the pigmented retina. Throughout all stages examined, mitotic figures were found lying exclusively adjacent to the intraretinal space. Early in the lens pit, they were confined to the free epithelial surface, and later were facing the cavity of the lens vesicle. The proliferative activity was the most intensive in the 6th week, whereas it decreased significantly in the later stages. Additionally, when proliferative activities were compared, the peripheral retina appeared to be less mature than the central before the 9th week. In the earliest analysed stage, cell proliferation might be associated with the sculpturing of the optic cup and stalk, the cornea, and the lens. In the 6th week, the most intensive proliferation seems to be involved not only in the further morphogenesis of the optic cup and the lens vesicle but also in the retinal neurogenesis. At later stages, the decreased proliferation might participate in the neurogenesis of the outer neuroblast zone and the secondary lens fibre formation.

Biomarkers↗

PubMed2003

Role of apoptosis and mitosis during human eye development.

The spatial and temporal distribution as well as ultrastructural and biochemical characteristics of apoptotic and mitotic cells during human eye development were investigated in 14 human conceptuses of 4-9 postovulatory weeks, using electron and light microscopy. In the 5th developmental week, apoptotic and mitotic cells were found in the neuroepithelium of the optic cup and stalk, being the most numerous at the borderline between the two layers of the optic cup, and at the place of transition of the optic cup into stalk. They were also found at the region of detachment of the lens pit from the surface ectoderm. In the later developmental stages (the 6th-the 9th week), apoptotic and mitotic cells were observed in the neural retina and the anterior lens epithelium. Throughout all stages examined, mitotic cells were found exclusively adjacent to the lumen either of the intraretinal space or the optic stalk ventricle, or were restricted to the superficial epithelial layer of the lens primordium. Unlike mitotic cells, apoptotic cells occurred throughout the whole width both of the neuroepithelium and the surface epithelium. Ultrastructurally, apoptotic cells were characterised by round- or crescent-shaped condensations of chromatin near the nuclear membrane, while in the more advanced stages of apoptosis by apoptotic bodies. The distribution of caspase-3-positive cells coincided with the location of apoptotic cells described by morphological techniques indicating that the caspase-3-dependent apoptotic pathway operates during the all stages of human eye development. The location of cells positive for anti-apoptotic bcl-2 protein was in accordance with the regions of eye with high mitotic activity, confirming the role of bcl-2 in protecting cells from apoptosis. In the earliest stage of eye development, apoptosis and mitosis might be associated with the sculpturing of the walls of optic cup and stalk, while high mitotic activity along the intraretinal space and optic stalk ventricle indicates its role in the gradual luminal closure. These processes also participate in the detachment of the lens pit epithelium from the surface ectoderm as well as in further closure of the lens vesicle. Later on, both processes seem to be involved in the neural retina differentiation, lens morphogenesis and secondary lens fibre differentiation.

Caspase 3↗

PubMed2002

Expression of intermediate filaments and desmosomal proteins during differentiation of the human spinal cord.

Differentiation of the human spinal cord and involution of its caudal end were investigated in 4-9-week human conceptuses using immunofluorescence and electron microscopy. In the spinal cord, several types of intermediate filament proteins and desmoglein were expressed in parallel: in early stages (4 to 6 weeks), neurofilaments were expressed in low amounts only in the neuroblast processes of the marginal layer. At 6 weeks, differences in staining intensity and distribution patterns of neurofilaments became apparent between lumbar and sacrococcygeal (tail) parts of the spinal cord. Neurofilament expression increased in the mantle and marginal layers of the lumbar spinal cord coinciding with advancing neurogenesis. In contrast, neurofilament expression decreased in the sacrococcygeal spinal cord in association with regression of all tail organs. Regression was characterized by the appearance of large amounts of dead cells and macrophages. Strong vimentin expression was found in neuroepithelial (ependymal) cells and in the radial glia of the spinal cord throughout all stages examined. Coexpression of vimentin and glial fibrillary acidic protein was found only in the radial glia in the earliest developmental stage. Desmoglein was expressed in low amounts around the central canal which was probably associated with the immature junctional complexes that were present between ependymal cells. In conclusion, temporal and spatial distribution patterns of intermediate filament proteins in specific cell populations characterizes differentiation and caudal involution of the human spinal cord.

Cell Differentiation↗