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Biomedical subjects

A Vaheri

Publications and source records attributed to A Vaheri.

At least 235 records · Page 13Linked to original sources
PubMed1989

Clonal variation in the production of tumor-associated alpha 2-macroglobulin in a malignant human melanoma and association with growth stimulation.

alpha 2-Macroglobulin (alpha 2-M) is known as a wide-spectrum proteinase inhibitor and to bind covalently certain growth factors. We have previously characterized tumor-associated alpha 2-M synthesized and secreted by human tumor cell lines. Of the cell lines studied, the melanoma cell line HMB-2 produced the largest amount of this glycoprotein. Immunofluorescence staining of cultured HMB-2 cells suggested that the cell population is heterogeneous with respect to alpha 2-M production. We have now isolated clones from the parental HMB-2 cells and characterized eight representative ones in detail. They varied considerably in the quantity of alpha 2-M secreted, from 4.2 to 46.5% of total protein. No relationship between the production of alpha 2-M by these clones and their pigmentation or tumorigenicity in nude mice was found. However, statistically there was a strong correlation between the modal chromosome number and population doubling time (r2 = 0.88, P less than 0.001) and also between the modal chromosome number and alpha 2-M production (r2 = 0.73, P less than 0.01). The growth rate of the clones correlated with the level of alpha 2-M in culture medium (r2 = 0.69, P less than 0.01). Clones with lower alpha 2-M production had a proportionally shorter population doubling time than the clones with intermediate or high production. Northern hybridization indicated quantitative variation in the alpha 2-M mRNA expressed by the parental cells and the clones, that was comparable but not identical with the quantity of alpha 2-M in the respective culture media; both parental cells and clones expressed platelet-derived growth factor A-chain mRNAs with little difference in levels. Serum-free medium from low alpha 2-M producer clones stimulated normal stationary fibroblasts significantly more than clones producing intermediate or high amounts of alpha 2-M. alpha 2-M decreased and anti-alpha 2-M IgG increased the stimulation. These results suggest that production of tumor-associated alpha 2-M is related to both autocrine and paracrine growth-stimulating activity of the tumor cells.

Biomarkers, Tumor↗
PubMed1989

Elevated cerebrospinal fluid fibronectin concentration at diagnosis indicates poor prognosis in children with acute lymphoblastic leukemia.

We investigated whether the concentration of fibronectin (FN) in the cerebrospinal fluid (CSF) could be used for identifying patients with subclinical blast-cell infiltration in the central nervous system (CNS) and an increased risk of CNS relapse later in the course of their leukemia. Our series comprised 36 children with newly diagnosed acute lymphoblastic leukemia (ALL). The mean follow-up time was 54 months (range 5 to 96 months). The median concentration of CSF-FN at diagnosis was 2.24 mg/l (range 0.78 to 7.04 mg/l). The 3-year continuous complete remission rate for the 16 patients with CSF-FN concentrations less than or equal to 2 mg/l was 93% as compared with 37% for the 19 patients with CSF-FN greater than 2 mg/l (p = 0.001). When multivariate analysis was performed, the CSF-FN concentration retained its prognostic significance. When all relapses were considered as failures, the relative risks of relapse for patients with CSF-FN less than or equal to 2 mg/l and greater than 2 mg/l were I and 15.8 (95% confidence limits 1.8-135.6, p less than 0.02), respectively. If only CNS relapses (isolated and combined) were considered as failures, relative risks for the above-mentioned groups were I and 11.6 (1.4-99.5, p less than 0.05), respectively. We conclude that determination of the CSF-FN concentration may provide a new means of evaluating the CSF in children with ALL and may prove to be a sensitive indicator of leukemic CNS infiltration.

Adolescent↗
PubMed1989

Plasminogen activator and its enhancement in differentiating mouse Friend erythroleukemia cells.

Urokinase-type plasminogen activator (u-PA) activity was found in the medium as well as in the lysates of cultured uninduced Friend leukemia (FL) cells. PA activity progressively increased during the cell differentiation induced by dimethyl sulphoxide (DMSO), 4-hydroxy-3-methoxybenzaldehyde or hypoxanthine. Both the differentiation and the enhancement of PA activity in cultures of DMSO-induced cells were blocked by treating the cells with 1 microM dexamethasone. A highly significant correlation (rs = 0.93) was found between the number of hemoglobinized cells and the rate of PA secretion, indicating that the increase in PA activity coincides with late events of the differentiation process. FL cells specifically adhere to fibronectin-coated surfaces but tend to lose this property during the differentiation process. Anti-u-PA IgG antibodies promoted the attachment of differentiating cells to fibronectin-coated surfaces, suggesting that u-PA plays a role in the detachment of FL cells from fibronectin immobilized on the growth substratum.

Animals↗
PubMed1989

Effect of measles, mumps, rubella vaccination on pattern of encephalitis in children.

462 patients (269 males, 193 females, aged from 1 month to 16 years) with encephalitis were treated at the Children's Hospital, University of Helsinki, over a 20-year period. The incidence of encephalitis was 8.3/100,000 child-years (range 19.8 in 1974 to 2.5 in 1985 and 1986). The organisms most commonly associated with encephalitis in children were mumps, measles, and varicella viruses, and Mycoplasma pneumoniae. After the start of the nationwide measles, parotitis, and rubella (MPR) vaccination programme in 1982 in Finland, encephalitides associated with these viruses seem to have totally vanished. Currently the pathogens most often associated with childhood encephalitides are varicella-zoster, M pneumoniae, and enteroviruses. 3% of the 462 patients died from their illness, and 7% became severely damaged, with the poorest outcome occurring after multiple infections, and herpes simplex virus, cytomegalovirus or M pneumoniae infections. The decline in the total number of cases of encephalitis was not accompanied by a decrease in number of patients with a poor outcome. Patients with treatable encephalitides due, for example, to M pneumoniae and herpes viruses, need prompt attention.

Adolescent↗
PubMed1989

Plasmin and fibronectin degradation in chronic secretory otitis media.

Mucoid effusions from 39 children with secretory otitis media, altogether 42 specimens, were analyzed for proteolytic activity using radial caseinolysis procedures, for fibronectin using a solid-phase enzyme immunoassay, and for fibronectin fragmentation using immunoblotting. All samples contained proteolytic activity, tentatively identified as plasmin on the basis of comigration with purified human plasmin in zymographic analysis. In 19 specimens the plasmin level exceeded 1 microgram/mg of protein; the highest value recorded was 18.7 micrograms/mg. Low levels of net plasminogen activator activity were found in 12 specimens and identified as urokinase according to comigration with the urokinase standard in zymography. Fibronectin was detected in all but one of the 42 specimens; in seven specimens the levels exceeded those in normal plasma, calculated per milligram of total protein. Extensive fragmentation of fibronectin was found in 19 specimens, correlating with high plasmin levels. The results are indicative of an ongoing proteolytic process in secretory otitis media and suggest that plasmin-caused degradation of the fibronectin-containing basement membrane and subsequent formation of granulation tissue may be involved in the development of adhesive middle ears.

Child↗
PubMed1989

Cytovillin and other microvillar proteins of human choriocarcinoma cells.

Microvilli were isolated from cultured human JEG-3 choriocarcinoma cells using a gentle shearing method. The protein components of the isolated microvilli were examined by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. The major Mr 42,000 and Mr 100,000 polypeptide bands reacted with anti-actin and anti-alpha-actinin antisera, respectively. Extraction of the isolated JEG-3 microvilli with Triton X-100 left an insoluble cytoskeletal residue containing mainly actin, alpha-actin, and polypeptides of Mr 200,000, 55,000 and 35,000. The Mr 35,000 polypeptide remained insoluble only at high concentrations of free Ca2+. Immunoblotting analysis of the JEG-3 microvilli indicated that they were devoid of tropomyosin, although the total JEG-3 protein lysates gave a strong positive reaction with anti-tropomyosin antiserum. The different subcellular localization of cytovillin and tropomyosin was also shown by indirect immunofluorescence microscopy. Cytovillin, an Mr 75,000 microvillus-specific membrane protein of JEG-3 cells, existed in an oligomeric form (dimer or trimer) as shown by gel filtration of Triton X-100 solubilized microvillar proteins and by native polyacrylamide gel electrophoresis of purified cytovillin. Disulfide bridges were not involved in the aggregation, because the mobility of cytovillin was similar under reducing and nonreducing conditions in SDS-PAGE. Cytovillin was shown to be closely related to ezrin, a minor component of chicken intestinal brush border microvilli.

Calcium↗
PubMed1989

Down-regulation of proteolytic activity in 12-O-tetradecanoyl-phorbol-13-acetate-induced K562 leukemia cell cultures: depletion of active urokinase by excess type 1 plasminogen activator inhibitor.

The human chronic myeloid leukemia cell line K562 acquires several megakaryoblastoid features when cultured in the presence of the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA). We observed strongly increased secretion of several proteins into the culture media of K562 cells within a few hours of TPA treatment. Two of the major secreted polypeptides were identified by immunoprecipitation from media of metabolically labeled cultures as the tissue inhibitor of metalloproteinases (TIMP) and the type 1 plasminogen activator inhibitor (PAI-1). Maximal amounts of PAI-1 mRNA and secretion of PAI-1 polypeptides were observed after 24 hr of TPA treatment and PAI-1 persisted at elevated levels for several days. The induction of PAI-1 mRNA was dependent on de novo protein synthesis. Uninduced and induced cells secreted urokinase plasminogen activator in its single-chain proenzyme form (pro-u-PA), which was cleaved extracellularly to the active two-chain form as shown by pulse-chase labeling experiments. Upon TPA induction, the secretion of u-PA polypeptides increased severalfold, and there was a transient accumulation of pro-u-PA in the culture medium. However, this did not lead to increased u-PA activity in the cultures, since active u-PA was removed by complex formation with the large excess of coinduced PAI-1. Induction of u-PA mRNA was biphasic: The first peak of about tenfold increase in steady-state u-PA mRNA at 3 hr was followed by a steep decline to the baseline level at 12 hr, and a second, slower accumulation of u-PA mRNA occurred over the next few days. The biphasic accumulation of u-PA mRNA was also reflected in u-PA protein synthesis. We conclude that concerted changes in favor of a nonproteolytic extracellular environment occur in TPA-induced K562 cultures undergoing megakaryoblastoid differentiation. These changes include excessive secretion of TIMP and inhibition of the induced u-PA by the simultaneous accumulation of PAI-1.

Cell Line↗
PubMed1989

Induction of morphological differentiation of human neuroblastoma cells is accompanied by induction of tissue-type plasminogen activator.

Human SH-SY5Y neuroblastoma cells treated with retinoic acid, 12-O-tetradecanoyl-phorbol-13-acetate (TPA) or nerve growth factor differentiated morphologically to neuronlike cells with increased amounts of neurofilament protein and mRNA. All three effectors induced an increase in the amount of relative molecular weight (Mr) 70,000 tissue-type plasminogen activator (t-PA) and its mRNA, as determined by immunocapture, enzyme activity, and Northern blotting analyses. About 90% of the t-PA activity was secreted to the culture medium. In contrast, of the three effectors studied, only TPA induced transcription of the proto-oncogene c-fos, studied as a control gene responsive to various stimuli, and induced a rapid increase in urokinase-type PA (u-PA). Most of the u-PA activity induced by TPA remained cell-associated. Because induction of differentiation correlated closely with induction of t-PA, and not u-PA, the authors propose that t-PA may have a functional role in the morphological differentiation of neuronal cells.

Cell Differentiation↗
PubMed1989

Histochemical study of alkali-burned rabbit anterior eye segment in which severe lesions were prevented by aprotinin treatment.

Activities of different enzymes (acid glycosidases, phosphatases, Na+ - K+ -dependent ATPase, proteases, dehydrogenases) and acid glycosaminoglycans were studied by histochemical methods in sections of rabbit anterior eye segments after experimental alkali burn and treatment with aprotinin, an inhibitor of plasmin and other serine proteinases. Solutions of sodium hydroxide (0.25-1.0 M) were applied on corneas using 12-mm-diameter plastic tube for 15-60 s. After wiping with cotton and rinsing with tap water aprotinin solutions were applied in saline (in experimental animals) and saline (in control animals) dropwise in 12-h intervals for a month. Within the first two weeks aprotinin was used at a concentration of 5000 IU/ml. During the subsequent two weeks the aprotinin concentration was reduced to 2500 IU/ml. Striking differences in enzyme activities and in the healing between treated and untreated eyes were found. Without aprotinin, ulcers developed in most corneas within 3 weeks and plasmin was regularly demonstrated in tears and in the aqueous. When aprotinin treatment was started within 24 h after the burn, the number of enzymatically active inflammatory cells was significantly lower, not only in the cornea itself but also in the whole anterior eye segment. With aprotinin treatment no ulcerations and no plasmin in tears and the aqueous were observed and the corneas healed within a month. The healing process started from the zone of enzymatically activated corneal cells in the unburned zone at the corneal periphery. In the regenerating epithelium and endothelium high activities of Na+ -K+ -dependent ATPase, gamma-glutamyltransferase, lactate and succinate dehydrogenases appeared very soon.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Phosphatase↗
PubMed1989

Contact lens wear is associated with the appearance of plasmin in the tear fluid--preliminary results.

We determined biochemically the plasmin concentration in tear fluid from 50 externally healthy eyes and from 49 eyes during contact lens (CL) wear. After cessation of CL wear, samples were collected again from 41 of the 49 eyes. Plasmin was detected more frequently (P less than 0.0001) in the CL-wearing group (75.5%) than in the control group (20%). After the cessation of CL wear (3-21 days), the frequency of plasmin detection in tear fluid decreased significantly (P less than 0.0006) but was still higher (39%) than in the control group. We conclude that the occurrence of plasmin in tear fluid is correlated with CL wear. The proteolytic activity of plasmin may contribute to the development of corneal epithelial pathology associated with CL wear.

Contact Lenses↗
PubMed1989

Activation of pro-urokinase and plasminogen on human sarcoma cells: a proteolytic system with surface-bound reactants.

Human HT-1080 fibrosarcoma cells produce urokinase-type plasminogen activator (u-PA) and type 1 plasminogen activator inhibitor (PAI-1). We found that after incubation of monolayer cultures with purified native human plasminogen in serum-containing medium, bound plasmin activity could be eluted from the cells with tranexamic acid, an analogue of lysine. The bound plasmin was the result of plasminogen activation on the cell surface; plasmin activity was not taken up onto cells after deliberate addition of plasmin to the serum-containing medium. The cell surface plasmin formation was inhibited by an anticatalytic monoclonal antibody to u-PA, indicating that this enzyme was responsible for the activation. Preincubation of the cells with diisopropyl fluorophosphate-inhibited u-PA led to a decrease in surface-bound plasmin, indicating that a large part, if not all, of the cell surface plasminogen activation was catalyzed by surface-bound u-PA. In the absence of plasminogen, most of the cell surface u-PA was present in its single-chain proenzyme form, while addition of plasminogen led to formation of cell-bound two-chain u-PA. The latter reaction was catalyzed by cell-bound plasmin. Cell-bound u-PA was accessible to inhibition by endogenous PAI-1 and by added PAI-2, while the cell-bound plasmin was inaccessible to serum inhibitors, but accessible to added aprotinin and an anticatalytic monoclonal antibody. A model for cell surface plasminogen activation is proposed in which plasminogen binding to cells from serum medium is followed by plasminogen activation by trace amounts of bound active u-PA, to form bound plasmin, which in turn serves to produce more active u-PA from bound pro-u-PA. This exponential process is subject to regulation by endogenous PAI-1 and limited to the pericellular space.

Cell Line↗
PubMed1989

Neonatal herpes simplex virus infection: a report of 43 patients.

We present a series of 43 infants with neonatal herpes simplex virus infection treated at the Children's Hospital, University of Helsinki, during a 16-year period from 1970 to 1985. Twelve mothers (28%) had a history of genital herpes during pregnancy, and two had had labial herpes infection. Eight infants (19%) were delivered by cesarean section. In 14 (33%) infants symptoms appeared within 24 hours and in 26 (61%) they appeared within 7 days. The presenting symptoms were neurologic in 79%, cutaneous in 30%, respiratory in 19%, cyanosis/pallor/grayish skin in 16%, irritability in 12% and fever in 7%. Herpes simplex virus was detected most early and frequently in pharyngeal swabs, in one-third on Postnatal Days 2 to 5. Cerebrospinal fluid contained an increased amount of protein and/or pleocytosis in 72%. Abnormal electroencephalographic background activity appeared in 56% and electrical paroxysms in 41%. Six infants (14%) died, 9 (21%) were damaged severely and 6 (14%) were moderately or mildly damaged. Poor prognosis was associated with acute maternal illness at delivery, prematurity, visceral involvement and/or electrical paroxysms in the electroencephalograms. This study underlines the occurrence of intrauterine transmission of herpes virus, infections with neurologic manifestations, early symptomatology and the need for prompt diagnosis, brain biopsy in selected patients and antiviral therapy in neonates with herpes virus infection.

Adolescent↗
PubMed1989

Tissue-type plasminogen activator in subretinal fluid.

The plasminogen activation system is quantitatively the major mechanism of extracellular proteolysis. To evaluate its role in retinal detachment, plasmin and plasminogen activators were measured in subretinal fluid (SRF) from 12 eyes of twelve patients. Plasmin was detected in 5 eyes (mean 6.26 micrograms/ml, SD = 3.7 micrograms/ml). Tissue-type plasminogen activator was present in 5 eyes (mean activity 0.33 IU/ml, SD = 0.24 IU/ml) but the activity did not associate with the plasmin activity in all of the SRF samples. Urokinase-type plasminogen activator was not detected in SRF. We conclude that the plasmin system has been activated in SRF in some eyes with retinal detachment with tissue-type plasminogen activator as the predominant activator. Plasmin in SRF may enhance dispersion of pigment epithelial cells into the subretinal space and the vitreous, a phenomenon seen frequently in eyes with retinal detachment.

Adult↗
PubMed1989

Plasmin and plasminogen activator activities in tear fluid during corneal wound healing after anterior keratectomy.

Plasmin can degrade fibronectin and laminin, two important components of the extracellular matrix facilitating cell sliding and healing following a wound. In this study we investigated the relationship between the tear fluid level of plasmin and plasminogen activator and the healing of a corneal wound. Anterior keratectomy (AKE) was performed for seven rabbits (11 eyes). Eight eyes were rewounded after re-epithelialization. Tear fluid samples were collected with capillaries before wounding and during wound healing. Plasmin and plasminogen activator (PA) activities were determined using radial caseinolysis procedures. After AKE the plasmin concentrations increased rapidly, from a mean (+/- SEM) of 3.9 +/- 0.9 micrograms/ml to a mean of 37.9 +/- 7.8 micrograms/ml (p less than 0.01), and decreased during wound healing. Rewounding also resulted in an increase in plasmin concentration in the tear fluid (from a mean of 2.9 +/- 0.6 micrograms/ml to a mean of 5.0 +/- 1.1 micrograms/ml; p greater than 0.05). The PA activity showed an inverse trend as it decreased after AKE from a mean of 2.0 +/- 0.6 IU/ml to a mean of 0.3 +/- 0.1 IU/ml (p less than 0.001). During wound healing and re-epithelialization, the PA activity increased again, to 2.1 +/- 0.3 IU/ml (p less than 0.001). Abrasion of the newly grown epithelium in eight eyes caused a second elevation of PA activity which was not significant. This study demonstrates a close association between the healing of corneal wounds and changes in the plasmin and PA activities in tear fluid. Determination of the activity of these enzymes may therefore be useful for monitoring corneal wound healing.

Animals↗
PubMed1989

Plasmin-like proteinase associated with high molecular weight complexes in blister fluid of bullous pemphigoid.

Blister fluid from tense bullae of 10 patients with bullous pemphigoid was investigated using a radial caseinolysis assay and zymography. Proteolytic activity, varying from 4.7 to 10 micrograms/ml, was found in 3 out of 10 patients, by using the caseinolysis assay. Zymography revealed that a major part of this caseinolytic activity co-migrated with plasmin standard. In addition, in the zymography, proteolytically active high molecular weight complexes were seen. This characteristic pattern was seen in the zymography of both positive and negative samples in the caseinolysis assay. These high molecular weight complexes were not seen in the zymography of the blister fluid of 2 patients with epidermolysis bullosa or in the suction blister fluid of 3 healthy control patients. These findings suggest that plasmin is generated at some phase of the blister formation, being possibly involved in the pathomechanism of bullous pemphigoid.

Blister↗
PubMed1988

Tumor-associated alpha-2-macroglobulin in human melanomas.

We and others have previously shown that human melanoma cell lines in culture synthesize alpha-2-macroglobulin (alpha 2M). We have now studied melanomas from 30 patients for the presence of alpha 2M using the peroxidase anti-peroxidase technique on histologic sections from paraffin-embedded tissues and primary antibody raised against tumor-associated alpha 2M in rabbits. alpha 2M was detected in 10 of the 30 melanomas studied. In all but 2 cases the presence of alpha 2M was restricted to solitary tumor cells or to solitary foci of tumor tissue. In one case of melanoma almost all tumor cells were positive for alpha 2M, while in the others between 20% and 50% of tumor cells were positive. In all but one of the melanomas, the positivity was characteristic of epithelioid or large-cell type or was confined to this component in melanomas with more than one cell type. In 4 positive cases, differences in the extent of alpha 2M-containing tumor tissue were observed between primary tumor and metastases or metastases from different localizations, with equivocal trend. Clinical follow-up of the melanoma patients suggested that alpha 2M-positively tends to correlate with an unfavorable prognosis.

Humans↗