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Biomedical subjects

L Laitinen

Publications and source records attributed to L Laitinen.

At least 37 records · Page 2Linked to original sources
PubMed1990

The alpha 1-alpha 6 subunits of integrins are characteristically expressed in distinct segments of developing and adult human nephron.

We studied the distribution of the alpha 1-alpha 6 subunits of beta 1 integrins in developing and adult human kidney using a panel of mAbs in indirect immunofluorescence microscopy. Uninduced mesenchyme displayed a diffuse immunoreactivity for only the alpha 1 integrin subunit. At the S-shaped body stage of nephron development, several of the alpha subunits were characteristically expressed in distinct fetal nephron segments, and the pattern was retained also in the adult nephron. Thus, the alpha 1 subunit was characteristically expressed in mesangial and endothelial cells, the alpha 2 in glomerular endothelium and distal tubules, the alpha 3 in podocytes, Bowman's capsule, and distal tubules, and the alpha 6 subunit basally in all tubules, and only transiently in podocytes during development. Unlike the alpha 3 and alpha 6 subunits, the alpha 2 subunit displayed an overall cell surface distribution in distal tubules. It was also distinctly expressed in glomerular endothelia during glomerulogenesis. The beta 4 subunit was expressed only in fetal collecting ducts, and hence the alpha 6 subunit seems to be complexed with the beta 1 rather than beta 4 subunit in human kidney. Of the two fibronectin receptor alpha subunits, alpha 4 and alpha 5, only the latter was expressed, confined to endothelia of developing and adult blood vessels, suggesting that these receptor complexes play a minor role during nephrogenesis. The present results suggest that distinct integrins play a role during differentiation of specific nephron segments. They also indicate that alpha 3 beta 1 and alpha 6 beta 1 integrin complexes may function as basement membrane receptors in podocytes and tubular epithelial cells.

Adult↗
PubMed1990

Psophocarpus tetragonolobus agglutinin reveals N-acetyl galactosaminyl residues confined to endothelial cells and some epithelial cells in human tissues.

We studied the binding of Psophocarpus tetragonolobus agglutinin (PTA) conjugates to human adult tissues. In all kidney specimens studied, PTA bound in a blood group-independent way to endothelia in glomerular and intertubular capillaries as well as in larger vessels. In addition, a heterogeneous binding to collecting duct cells was seen. In specimens of human smooth, cardiac, and skeletal muscle, cerebellum, lung, thyroid gland, liver, proliferative endometrium, and placenta, PTA bound only to endothelial of capillaries and larger vessels. In epidermis and gingiva, PTA conjugates additionally revealed reactivity with keratinocytes. Similarly, in salivary gland, urinary bladder, gastrointestinal tract, mammary gland, and renal pelvis, PTA reacted with some epithelial cell layers. The PTA conjugates gave an even cell surface membrane staining of cultured umbilical vein endothelial cells. Lectin-affinity binding of radioactively surface-labeled endothelial cells showed that PTA and Ulex europaeus I agglutinin (UEA-I) recognized related major cell surface glycoproteins. The results with PTA conjugates show that certain N-acetyl galactosaminyl residues are, in addition to some epithelial cells, confined to endothelial cells in human tissues.

Acetylgalactosamine↗
PubMed1990

Distribution of beta 1 and beta 3 integrins in human fetal and adult kidney.

The distribution of beta 1 and beta 3 integrins was studied in fetal and adult human kidneys by indirect immunofluorescence microscopy. In the developing kidney, the cells of the undifferentiated metanephric blastema displayed strong cell surface-confined beta 1 integrin immunoreactivity, whereas the cells of primary vesicles and comma- and S-shaped bodies reacted more weakly. In mature fetal as well as adult glomeruli, beta 1 integrins were distinctly localized, apparently confining to the basal cell surfaces of endothelial cells and podocytes abutting the glomerular basement membrane. In adult proximal tubules, beta 1 integrin immunoreactivity was strictly confined to the basal aspect of the epithelial cells, being absent laterally, which is unusual for membrane proteins of polarized epithelial cells. A more diffuse overall immunoreactivity was seen in distal tubules and collecting ducts. The epithelial cells of developing proximal and distal tubules displayed an overall distribution of beta 1 integrins. In each case, talin immunoreactivity followed that of beta 1 integrins. Compared with beta 1 integrins, beta 3 integrins showed a more restricted distribution, and differences were seen in the reactions of mono- and polyclonal antibodies. In developing glomeruli, beta 3 integrin immunoreactivity was prominently seen in the cells of Bowman's capsule, possibly revealing the presence of vitronectin receptor. Solitary cells, that reacted also with antibodies to the platelet glycoprotein IIb, were consistently detected in fetal glomeruli, suggesting the presence of megakaryocytes. The results show that during nephrogenesis, beta 1 integrins become distinctly polarized both in glomerular endothelial cells and podocytes, as well as in the epithelial cells of proximal tubules.

Adult↗
PubMed1990

Differential distribution of tenascin in the normal, hyperplastic, and neoplastic breast.

We studied by immunohistochemistry the distribution of tenascin with the monoclonal antibody 100EB2, and compared it with that of laminin in breast tissue samples from fetal, adult resting, lactating, and aging parenchyma, variants of fibrocystic disease, fibroadenomas, cystosarcoma phylloides, and ductal and lobular carcinomas. Monoclonal antibodies were applied to cryosections by the avidin-biotin-complex method; selected samples were studied by double immunofluorescence, and by Western blot analysis. In adult resting and aging breasts, tenascin immunoreactivity was noted in the periductal and periacinar stromal regions as thin irregular bands; in the lactating breast, broader periductal bands were observed. In these samples, laminin immunoreactivity was a single continuous line around ducts, acini, and vessels. In fetal breasts, tenascin appeared as thick periductal bands, whereas laminin remained as a delicate single line. In FCD, tenascin increased around ducts showing hyperplasia, papillomas and apocrine metaplasia, whereas laminin retained its delicate linear pattern. Similar patterns were seen in fibroadenomas and cystosarcoma phylloides with variable tenascin reactivity in the stroma beyond the ducts. Tenascin immunoreactivity was markedly increased around ducts containing in situ carcinoma appearing as broad bands, whereas that of laminin showed a linear, frequently discontinuous appearance. Prominent stromal tenascin immunoreactivity was seen in infiltrating ductal and lobular carcinomas, whereas laminin was virtually absent save for scattered lines. The abundance of tenascin in the carcinomatous stroma contrasted with its scarcity in the non-neoplastic stromal regions. By Western blotting, both chains of tenascin with molecular weights 250,000 and 180,000 were shown in ductal and lobular carcinomas as well as in normal breast. Tenascin immunoreactivity was noted in the periepithelial stromal regions of adult resting and aging breast ducts and acini. The amount of tenascin was moderately enhanced in certain physiologic conditions (fetal growth, gestation), as well as hyperplasias, dysplasias (fibrocystic disease) and benign tumors, whereas it was markedly enhanced in intraductal and infiltrating carcinomas. During fetal mammary development, adult physiologic and pathologic hyperplasias, and in carcinomas, the increasing tenascin reactivity contrasted with the stable or decreasing laminin reactivity.

Adult↗
PubMed1989

Differential expression of galactose and N-acetylgalactosamine residues during fetal development and postnatal maturation of rat glomeruli as revealed with lectin conjugates.

A battery of fluorochrome- or peroxidase-coupled lectins, reacting with alpha- or beta-galactose (Gal), terminal N-acetylgalactosamine (GalNAc), or Gal-(beta 1-3)-GalNAc residues, was used to study the emergence and distribution of cellular glycoconjugates in developing and adult rat glomeruli. Neuraminidase pretreatment of the specimens was applied to monitor the maturation of the glomerular sialoglycoprotein coat. In the adult glomeruli, the lectin conjugates applied reacted sparsely or not at all, but most of them showed an increased reactivity with podocytes and/or the glomerular basement membrane after neuraminidase treatment. In the embryonic glomeruli, lectins reacting with beta-Gal residues prominently bound to the basement membranes, as revealed in double-staining with laminin antibodies. This reactivity decreased first during late postnatal development. Some terminal Gal-(beta 1-3)-GalNAc residues were noted in the earliest podocytes, but obviously soon became covered by sialylation. Furthermore, the developing podocytes prominently displayed alpha-Gal residues, as marked by Maclura pomifera (MPA) and Jacalin reactivities but not by the GSA-I conjugates. During postnatal maturation these reactivities also decreased. The GalNAc-specific Helix pomatia (HPA) and Helix aspersa (HAA) agglutinins bound to basement membranes of evolving podocytes but later revealed in the podocytes only a Golgi-like cytoplasmic reactivity. These two lectins showed a marked difference in their binding to tubular basement membranes. In lectin blotting experiments of electrophoretically separated polypeptides transferred onto nitrocellulose, the peanut agglutinin (PNA) and MPA conjugates revealed upon neuraminidase treatment a broad Mr 140,000 polypeptide, compatible with podocalyxin, both in isolated developing and adult glomeruli. The MPA conjugate revealed a similar polypeptide in developing glomeruli, even without neuraminidase treatment. Similar experiments with the HPA and HAA conjugates revealed different polypeptides in both adult and developing glomeruli. Obviously, in the rat kidney the maturation of the podocyte sialoglycoprotein coat and the glomerular basement membranes are multiphasic processes that continue even during late postnatal development.

Acetylgalactosamine↗
PubMed1989

A sixteen-factor personality test for predicting automobile driving accidents of young drivers.

The predictive value of the Cattell 16-factor personality test on the occurrence of automobile accidents among conscripts during their 11-month military service in a transportation section of Finnish Defense Forces was examined. Automobile driving experience before and during the follow-up as well as the occurrence of traffic accidents and penalties before and during the follow-up period were investigated. Complete data on personality, mileage, and traffic accidents plus penalties were obtained for 597 conscripts. In this population, altogether 91 automobile accidents were recorded for 82 conscripts. A logistic model showed that impulsivity and adventurousness (high score in factor H), naivete and excessive trustfulness (low score in factor L), and poor self-control (low score in factor Q3) predicted significantly, and guilt proneness and depression (high score in factor O) almost significantly the subsequent occurrence of motor vehicle accidents. Factors L and Q3 remained significant when only accidents of which the subject was found guilty were being predicted. All these personality factors are related to the control of emotions. The results indicate that the 16-factor personality test is valuable when selecting safe drivers in a population of young male adults with little previous driving experience.

Accidents, Traffic↗
PubMed1989

Expression of intermediate filaments (IF) in tissues and cultured cells.

Intermediate filaments are found in most nucleated cells as part of their cytoskeleton. Intermediate filaments are formed by different proteins in cells of major tissues types. Therefore, antibodies against intermediate filaments can be used in tissue typing, in the analysis of cell lineages during development and in the elucidation of the origin of unknown tumors.

Animals↗
PubMed1988

Expression of cellular glycoconjugates in transfilter-induced metanephric mesenchyme.

Expression of glycoconjugates during transfilter-induced differentiation of metanephric mesenchyme was studied by using fluorochrome- and peroxidase-coupled lectins. All cells in the uninduced metanephric mesenchyme expressed mannose, beta-D-galactose (beta-Gal), N-acetylglucosamine (GlucNAc), and terminal sialic acids. Additionally, solitary cells showed terminal alpha-D-galactose alpha-D-galactose (alpha-Gal) typical of mouse endothelial cells. During culture, undifferentiated mesenchymal cells seemed to disappear from induced explants, and many of the stromal cells between the evolving tubules presented terminal alpha-Gal residues. Similar positivity could be revealed in monolayer cultures of induced mesenchymes. A number of tubules in induced explants displayed alpha-L-fucosyl (Fuc) residues, characteristic of mature proximal tubules. Some terminal Ga1NAc residues, recognized only by Dolichos biflorus agglutinin, emerged in a few tubular cells after prolonged culture. The early tubules and glomerular bodies displayed a basement membrane presenting both terminal Ga1-(beta 1-3)-Ga1NAc and Ga1NAc residues. These positivities disappeared later from many tubular structures and glomerular bodies but persisted in tubules expressing proximal tubular differentiation. The glomerular bodies displayed only one cell type, reminiscent of maturing podocytes, presenting terminal Ga1-(beta 1-3)-Ga1NAc and Ga1NAc residues. Later these saccharide residues became covered by sialylation, as they could then be revealed only after treatment with neuraminidase. The results indicate that the segment-specific expression of saccharide residues during differentiation of nephron in vitro resembles the sequence seen in vivo. This study also suggests that the basement membranes surrounding the nephron show a stepwise, segment-specific maturation. Despite the presence of endothelial cells in the metanephric explants, only avascular glomeruli evolved in this differentiation model.

Animals↗
PubMed1988

Differential expression of the extra domain-containing form of cellular fibronectin in human placentas at different stages of maturation.

The distribution of the extra domain-containing form of cellular fibronectin was studied in human placentas at different stages of maturation by using the monoclonal antibody 52DH1 in indirect immunofluorescence. In early chorionic tissue (7 to 10 weeks post menstruationem) cellular fibronectin was codistributed with laminin and type IV collagen in the trophoblastic basement membranes. At weeks 11 to 12 the trophoblastic basement membranes were negative but positivity was typically revealed in distinct aggregates in the stromal tissue. In second-trimester and term placentas the immunoreactivity was confined to the vessel endothelia of villous stroma. Extravillous trophoblast cells seen in placentas at different stages did not show positivity. Double staining with the 52DH1 monoclonal antibody and polyclonal fibronectin antibodies showed that both in the early and term placentas there was much fibrillar positivity only revealed with the polyclonal antibodies. The present results show that cellular fibronectin is a prominent component of early trophoblastic basement membranes and may thus play a special role in the maturation of chorionic villi.

Antibodies, Monoclonal↗
PubMed1988

Dolichos biflorus agglutinin (DBA) reacts selectively with mast cells in human connective tissues.

Dolichos biflorus agglutinin (DBA) binds to N-acetyl-D-galactosamine (GalNAc) residues in glycoconjugates and agglutinates erythrocytes carrying blood group antigen A. In cryostat sections of various tissues from blood group-specified humans, fluorochrome-coupled DBA bound preferentially to fusiform connective tissue cells and to certain epithelial cells. The connective tissue cells were identified as mast cells by their typical metachromasia in consecutive staining with toluidine blue. Double labeling with DBA and conjugated avidin revealed two distinct populations of mast cells. In several tissues the DBA-reactive cells likewise displayed uniform avidin reactivity. In intestinal mucosa, however, morphologically distinct DBA-binding mast cells were found, which were labeled with the avidin conjugates only in specially fixed paraffin sections. DBA did not bind to vascular endothelial cells, which could be identified by double staining with antibodies to factor VIII-related antigen. Labeling with Helix pomatia agglutinin (HPA), another blood group A-reactive lectin, resulted in distinct blood group-dependent fluorescence of the endothelia. Sophora japonica agglutinin (SJA), a blood group B-reactive lectin, labeled vascular endothelial cells in tissues from blood group A, AB, and B donors. HPA and SJA reacted with small mast cells in the gastrointestinal mucosa but failed to label large mast cells in any of the tissues. These results indicate that the blood group reactivity of lectins, as determined by erythroagglutination, is not necessarily consistent with their reactivity with blood group determinants in tissue sections. Moreover, DBA conjugates appear to be a reliable probe for detection of mast cells in various human connective tissues.

Breast↗
PubMed1987

Griffonia simplicifolia lectins bind specifically to endothelial cells and some epithelial cells in mouse tissues.

The binding of Griffonia simplicifolia agglutinin-I (GSA-I) and the isolectins GSA-I-AB3 and GSA-I-B4, having affinity for some alpha-D-galactosyl and N-acetyl galactosaminyl residues was studied in different mouse tissues. In brain, cardiac muscle and skeletal muscle, the GSA-I-lectin conjugates showed prominent binding only to blood vessel endothelia. Similarly, in the liver and kidney cortex the GSA-I-conjugates selectively reacted with endothelial cells of the sinusoids and with intertubular and glomerular capillaries, respectively. However, a strong reactivity with the GSA-I-conjugates was additionally seen in the acinar cells of the pancreas, in the stratified squamous epithelia of skin and tongue, and in transitional epithelium. SDS-PAGE electrophoresis combined with the lectin-blotting technique indicated that a similar set of glycoproteins are responsible for the GSA-I binding, even in different tissues. Another lectin with specificity for alpha-D-galactose, the Maclura pomifera agglutinin, displayed a distinctly different distribution of binding sites, mainly in the basement membranes, of all mouse tissues studied. The results suggest that some alpha-D-galactosyl residues, recognized by the binding of GSA-I lectins, are preferentially expressed in endothelial cells of mouse tissues, and also provide further evidence that endothelial cells can present a highly specific surface glycosylation pattern.

Animals↗
PubMed1987

Changes in the glycosylation pattern during embryonic development of mouse kidney as revealed with lectin conjugates.

Distribution of lectin-binding sites in adult and developing mouse kidney was studied with fluorochrome- and peroxidase-coupled lectins. Effects of fixation methods on lectin-binding patterns were also compared. Un-induced mesenchymal cells and ureter bud of the early metanephros reacted with Concanavalin A, Lens culinaris, Ricinus communis I, and wheat germ agglutinins, whereas binding sites for both soybean and peanut (PNA) agglutinins were seen only in ureter bud tissue. On induction, PNA positivity rapidly appeared in the induced, condensed areas of the metanephrogenic mesenchyme. Early glomeruli expressed heterogeneously terminal galactosyl and N-acetylgalactosaminyl moieties in the podocytes. Later, these sites disappeared and were apparently covered by sialic acids. Endothelia also displayed a comparable sialylation of terminal saccharide moieties during maturation. Binding sites for many of the above lectins were also found in the developing proximal and distal tubules. Terminal fucosyl residues, characteristic of mature proximal tubules, appeared during day 13 of development. Dolichos biflorus agglutinin reactivity, typically seen in the collecting ducts, appeared by day 13. Griffonia simplicifolia-I-B4 isolectin reactivity was exclusively localized to endothelial in adult kidney cortex, but in embryonic kidneys reactivity with collecting duct and podocytes was also seen. These results suggest that the compartmentalized expression of cell glycoconjugates in adult mouse kidney is acquired in a sequential manner during development. Such sequential appearance of the mature glycosylation pattern probably reflects functional maturation of the nephron.

Animals↗
PubMed1987

Differential expression of the ED sequence-containing form of cellular fibronectin in embryonic and adult human tissues.

Monoclonal mouse hybridoma antibodies were obtained for secreted cellular fibronectin (cFn) from A8387 fibrosarcoma cells. One of them, 52-DH1 (DH), reacted exclusively with cFns but not with plasma Fns (pFns) in immunoblotting and solid-phase EIA. The DH antibody also recognized thermolysin cFn fragments and beta-galactosidase-Fn fusion protein which contained the ED sequence specific to at least some forms of cFns. On the other hand, the DH antibody failed to recognize a fusion protein that was otherwise identical but lacked the ED sequence. Thus, the antigenic determinant for the DH antibody was located to the ED sequence. The DH antibody was then used to study the expression of ED sequence containing cFn (EcFn). For comparisons, another monoclonal antibody, 52BF12 (BF), recognizing equally well both pFns and cFns, was used. Immunoblotting of pFn fragments indicated that this antibody had the antigenic determinant at or close to the cell-binding site of Fn. EcFn was revealed by the DH antibody in embryonic and adult fibroblasts and in a variety of other cultured normal and malignant human cells. In embryonic tissues EcFn was abundant in developing basement membranes, as shown in foetal kidney and muscle, while in adult tissues it was confined only to endothelia of larger blood vessels. Furthermore, in embryonic tissues the capillaries showed bright EcFn-positivity not found any more in adult tissues. Human plasma contained a small quantity of EcFn, which may hence have an endothelial origin. EcFn was also prominent in the stroma of malignant tumours as well as in reactive benign conditions, such as granulation tissue and decidual cells. The results suggest that EcFn is a form of the protein which may have a particular role in developing and reactive tissues in embryos and adults.

Adult↗
PubMed1985

Glomerular sialic acid in Heymann nephritis and diacetylbenzidine induced nephropathy in rats.

Glomerular sialic acid was chemically measured in rats with experimental proteinuria induced by N,N'-diacetylbenzidine (DAB) or with autoimmune Heymann nephritis. In DAB nephrosis and in Heymann nephritis the relative amount of glomerular protein was increased. In DAB nephrosis the quantity of sialic acid expressed per amount of protein was decreased, but expressed per amount of DNA, which reflects the number of cells, there was no significant change. In Heymann nephritis the amount of sialic acid was not significantly altered when expressed per amount of protein or per amount of DNA. In individual animals, the amount of glomerular sialic acid expressed per amount of protein or per amount of DNA did not correlate with the severity of proteinuria. An increase in the total number of glomerular cells was found only in Heymann nephritis. The results suggest that proteinuria in the reported models is not the result of changes in glomerular sialic acid.

Animals↗
PubMed1981

Effects of adrenergic and cholinergic drugs on electrical and mechanical activities of the rat cauda epididymidis in vitro.

Electrical and mechanical activities of the rat epididymis (at 29 +/- 1.1 cm from the junction of the vas deferens) were recorded in vitro. The frequency of the spontaneous activity was 2.7 +/- 0.15/min. Adrenaline, phenylephrine, isoprenaline and carbachol increased the basal tension, frequency and amplitude of the contractions. Phentolamine, an alpha-adrenergic blocking agent, abolished the stimulatory effects of adrenaline and isoprenaline, but not those of carbachol. Propranolol and metoprolol, beta-adrenergic blocking agents, did not inhibit the stimulatory effects of isoprenaline. Atropine abolished the response to carbachol. The results suggest that alpha-adrenergic receptors but not beta-receptors are present in the rat epididymis.

Action Potentials↗