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At least 19 recordsLinked to original sources
PubMed2026

A third-generation, high-affinity biparatopic anti-tau antibody inhibits intracellular tau aggregation seeded by Alzheimer's brain extracts.

BACKGROUND: Tau immunotherapy has recently shown clinical promise but required high dosing. We developed NIDB-3101, a novel third-generation, high-affinity anti-tau biparatopic antibody designed for superior tau binding, aggregation inhibition, and extended half-life. METHODS: NIDB-3101 binds tau's microtubule-binding region and C-terminal domains. Various binding and cellular functional assays using recombinants, but more importantly human AD extracts were used to assess NIDB-3101 benefits. Half-life mutations impact was assessed via FcRn binding and cellular assays recycling. RESULTS: NIDB-3101 exhibited sub-nanomolar affinity, binding a broad spectrum of pathological tau species in AD homogenates, inhibited AD extracts-induced cellular effect compared to benchmark antibodies. Mutations enhanced hFcRn-mediated cellular recycling. CONCLUSIONS: NIDB-3101 captures a broad spectrum of pathological tau species leading to strong cellular efficacy using human AD extracts, supporting further clinical development as a potential disease-modifying therapy for AD and related tauopathies.

tau Proteins↗
PubMed1985

Migration inhibition of an epithelial cell line by s-Con A and the effect on its invasiveness.

In an attempt to delineate the role of tumor-cell motility in the process of invasion, we compared the migration of NBT II in a two-dimensional migration assay with its migration in a three-dimensional invasion assay. Both systems were maintained with and without succinylated concanavalin A (s-Con A) dissolved in the culture medium. This lectin has a reversible inhibitory effect on the migration of cells in vitro. The migration of NBT-II aggregates, seeded in flasks containing 200 micrograms/ml s-Con A or without s-Con A, was studied by time-lapse photomicrography. In the presence of s-Con A, migration was immediately stopped. When the treated medium was replaced by culture medium to which 10 mM alpha-methyl-mannose was added, the inhibition of migration was abolished. The invasive capacity of NBT II in the presence or absence of s-Con A was studied by confronting precultured fragments of 9- to 11-day-old embryonic chick heart (0.4 mm in diameter) with NBT-II aggregates (0.2 mm) made in the presence or absence of s-Con A. Light microscopy showed no difference in the extent of invasion. To demonstrate the presence of s-Con A in the invading tumor cells, immunoperoxidase staining for Con A was done. The treated cultures stained positively while the controls were negative. The data presented here question the correlation between tumor-cell motility in two-dimensional system and the invasive behavior of these cells in three dimensions, and implies that the ability or inability of cells to migrate on plastic does not necessarily reflect their invasiveness in vitro.

Animals↗
PubMed1979

Stem cell growth and differentiation in Hydra attenuata. I. Regulation of the self-renewal probability in multiclone aggregates.

Interstitial stem cells in Hydra are rapidly proliferating multipotent stem cells which continuously give rise to precursors for nerve and nematocyte differentiation. Growth of the stem cell population is controlled by the cell cycle time of the stem cells and the self-renewal probability, Ps (the fraction of stem cells in each generation which divide to yield more stem cells). In normal Hydra the stem cell generation time is 24 h and Ps = 0.6; under these conditions the stem cell population doubles in 3.5 days. In the present experiments we have systematically investigated the dependence of Ps on stem cell density. We culture stem cells in a feeder layer system consisting of aggregates of nitrogen-mustard (NM)-inactivated Hydra cells. In this system stem cell density can be varied over a wide range by changing the number of clone-forming units (CFU) added to the aggregates. We have measured the growth rate of the stem cell population and the cell cycle of stem cells in NM aggregates after 4--7 days of culture. From these data we calculate the value of Ps. The results indicate that the growth rate decreases 4-fold as the number of CFU seeded per aggregate increases from 10 to 400. Under these same conditions the cell cycle remains constant. The values of Ps calculated from these results indicate the Ps decreases from 0.75 in aggregates seeded with 10--30 CFU to 0.55 in aggregates seeded with 200--400 CFU. These results support a model in which Ps is controlled by negative feedback from neighbouring stem cells. In addition, our experiments indicate that Ps decreases during the growth of stem cell clones. When only a few stem cells are seeded in aggregates, they give rise to isolated clones distributed throughout the aggregate. Ps decreases markedly within such clones as they grow in size presumably due to increasing stem cell content of the clones. Since Ps in such isolated clones declines with growth, we infer that the local stem cell concentration is what controls Ps and that the spatial range of the negative feedback signal is short compared to the dimensions of NM aggregates.

Animals↗
PubMed1991

Platelet aggregation inhibitors from the seeds of Swietenia mahagoni: inhibition of in vitro and in vivo platelet-activating factor-induced effects of tetranortriterpenoids related to swietenine and swietenolide.

The ether extract from the seeds of Swietenia mahagoni Jacq. (Meliaceae) was found to inhibit platelet-activating factor (PAF)-induced platelet aggregation. Systematic separation of the extract afforded twenty eight tetranortriterpenoids related to swietenine and swietenolide. Among them, several new compounds, named swietemahonin A, D, E, and G and 3-O-acetylswietenolide and 6-O-acetylswietenolide, showed a strong inhibition against PAF-induced aggregation in vitro and in vivo assays.

Animals↗
PubMed1979

Stem cell growth and differentiation in Hydra attenuata. II. Regulation of nerve and nematocyte differentiation in multiclone aggregates.

The differentiation of nerve cells and nematocytes from interstitial stem cells in Hydra has been investigated under conditions of changing stem cell density. Interstitial stem cells were cultured in a feeder layer system consisting of aggregates of nitrogen mustard-inactivated tissue. The aggregates were seeded with varying numbers of stem cells from 10 to 400 per aggregate; between 4 and 7 days later the rates of nerve and nematocyte differentiation were measured. Nerve differentiation was scored by labelling the stem cell population with [3H]-thymidine and counting nests of 4 proliferating nematoblasts. In both cases the numbers of differentiating cells were normalized to the size of the stem cell population. The results indicate that the rate of nematocyte differentiation increases as the concentration of stem cells increases in aggregates; under the same conditions the rate of nerve differentiation remains essentially constant. To calculate the numbers of stem cells entering each pathway per generation, a computer was programmed to simulate the growth and differentiation of interstitial stem cells. Standard curves were prepared from the simulations relating the rates of nerve and nematocyte differentiation to the fraction of stem cells committed to each pathway per generation. The rates of nerve and nematocyte commitment were then estimated from the experimentally observed rates of differentiation using the standard curves. The results indicate that nerve commitment remains constant at about 0.13 stem cells per generation over a wide range of stem cell concentration. Nematocyte commitment, by comparison, increases from 0.15 to 0.21 stem cells per generation as stem cell concentration increases in aggregates. The fact that the ratio of nerve to nematocyte commitment changes under our conditions suggests that stem cell commitment is not a stochastic process but subject to control by environmental stimuli.

Animals↗
PubMed1991

High resolution electrophoresis of soybean seed isoesterases.

A modified discontinuous buffer system for vertical polyacrylamide electrophoresis was developed with large changes in component concentration from the original Tris-HCl/Tris-glycine system of the Ornstein-Davis type. The new buffer system is able to resolve the fast soybean seed isoesterases crucial for cultivar discrimination. A higher number of anodic bands is obtained in comparison with separations under standard conditions. A "gelating boundary", resulting from the aggregation of seed proteins, is retarded and does not migrate out of the upper stacking gel. The same buffer modification is also beneficial to the separation of native seed proteins.

Buffers↗
PubMed1992

Retinoic acid-induced inhibition of metastatic melanoma cell lung colonization and adhesion to endothelium and subendothelial extracellular matrix.

The effect of pretreatment of metastatic B16 melanoma cells with 10(-6) M all trans-retinoic acid resulted in a significant inhibition of lung colonization following injection of 10(5) cells into the tail vein of syngeneic C57BL mice. Adhesion of melanoma cells to vascular endothelial cell monolayers, and subendothelial extracellular matrix was also inhibited by pretreatment with retinoic acid, as was tumour cell aggregation following seeding of pretreated cells on to 0.5% agar. Release of 35SO4 from radiolabelled subendothelial extracellular matrix by melanoma cells was essentially unaltered by retinoic acid pretreatment, as was the release of radiolabel from [3H]proline-labelled matrix, while plasminogen activator activity was enhanced in retinoic-acid-treated cells. These observed changes in adhesive properties may be responsible, at least in part, for the retinoic-acid-induced inhibition of lung colonization.

Animals↗
PubMed1987

Proliferation of human carcinoma cells in calcium-deficient culture medium may depend on autocrine growth factor(s).

The ability to proliferate in media with low calcium concentrations (less than 0.1 mM) at clonal seeding densities is a characteristic of malignant cells. Cells of the carcinoma line C-4I are an exception, and are unable to proliferate in medium with 0.02 mM calcium (LCM) when seeded at low densities. Conditioned medium, derived from a subline of C-4I cells that were adapted to grow in LCM, contained an acid-stable factor of greater than 8 kilodaltons molecular weight that mediated proliferation and colony formation of unadapted C-4I cells in LCM in a concentration-dependent manner. The effect was not related to enhanced cell attachment or spreading, and was maximal when the unadapted C-4I cells were seeded in aggregates of 2-20 cells rather than singly. Thus, calcium independence, a component of the neoplastic phenotype, may be mediated by autocrine tumor-cell-derived factor(s) and may involve long- and short-range cell interactions.

Calcium↗
PubMed1987

Differentiation-associated carbohydrate chain on human hematopoietic cells recognized by Clerodendron trichotomum lectin.

In the screening of hematopoietic cell line cell aggregations, the extract of Clerodendron trichotomum seed was found to aggregate K-562 and KG-1 specifically. In the flow cytometric analysis using FITC-conjugated purified CTL, it was confirmed that CTL recognizes the specific carbohydrate(s) which seem to appear only in the early stages of differentiation of myeloid (KG-1) and erythroid (K-562) cell line cells and erythrocytes. The CTL binding to K-562 cells was decreased by TPA treatment which is known to induce retrodifferentiation of K-562. It is also found that this carbohydrate(s) were shaded with NANA on the differentiated cells. In the erythrocyte, CTL receptor was partially shaded by NANA.

Carbohydrate Metabolism↗
PubMed1985

Soft agarose culture human tumour colony forming assay for drug sensitivity testing: [3H]-thymidine incorporation vs colony counting.

In vitro drug sensitivity testing, both by optical colony counting and by a [3H]-TdR incorporation assay, was performed on human tumour cells proliferating in soft agar cultures. Cells from two different human tumour cell lines, 5 different human tumour xenografts, and 94 different primary human tumour specimens of various histologic types were studied. Regression analysis comparing the results of the colony counting assay and the [3H]-TdR assay revealed good to excellent correlations between the two assay endpoints for quantitating the effect of in vitro anticancer drug exposure for a large number of different agents. The presence of pre-existing tumour cell aggregates complicates the performance of the optical colony counting assay. The [3H]-TdR incorporation assay is more sensitive and reproducible than the colony counting assay when performed on samples containing a large number of initially seeded tumour cell aggregates.

Antineoplastic Agents↗
PubMed1991

[A study of crystallization on urolithiasis in vitro].

The formation, growth and aggregation of calcium oxalate crystals were evaluated with a Coulter counter. CG-120 and sodium pentosan polysulfate (SPP) has inhibitory activity on calcium oxalate crystal formation, growth and aggregation in the seeded crystal system and whole urine system. In continuous crystallizer system, they inhibit the nucleation rate. A new system of observing the crystal formation and growth of fragmented stones after extracorporeal shock wave lithotripsy has been developed. CG-120 has an inhibitory effect on their growth. The deposition of calcium oxalate crystals in the rat kidney was induced, and the, the volume and number of crystals were estimated using a Coulter counter. SPP has an inhibitory effect on calcium oxalate crystal growth in vivo.

Animals↗
PubMed1985

Mechanisms of proteoglycan inhibition of hydroxyapatite growth.

Purified bovine nasal cartilage proteoglycans (aggregate and subunit containing fractions) and to a lesser degree, chondroitin 4-sulfate of physiological size, retard seeded hydroxyapatite (HA) growth in vitro. The large hydrodynamic size and high charge density of these macromolecules are believed to be associated with the ability of proteoglycans to inhibit HA formation and growth. We now demonstrate the involvement of the negative charges of proteoglycans in this inhibition by comparing the inhibitory ability of chondroitin 4-sulfate and its desulfated analog, and by comparing the growth of HA seed crystals coated either with proteoglycan aggregates or chondroitin 4-sulfate to that of uncoated crystals. In the desulfation experiments, desulfated chondroitin sulfate was a less efficient HA growth inhibitor than untreated, undesulfated chondroitin sulfate of similar molecular size. Dextran sulfate showed higher inhibitory effectiveness than unchanged neutral dextran. Both experiments suggest that sulfate groups play an important role in the regulation of mineral deposition by proteoglycans. In the coating experiment, precoating of HA seed crystals with proteoglycan aggregates decreased the amount of HA precipitated as a function of time, suggesting proteoglycans may block the active nucleating sites on HA surface and slow down the growth process. Chondroitin 4-sulfate had a similar but weaker coating effect. Neutral dextran, having little affinity for HA, had no effect.

Animals↗
PubMed1979

On the reduced intercellular adhesiveness of virally transformed BHK21 cells.

Baby hamster kidney fibroblasts (BHK21 cells) transformed by polyoma or Rous sarcoma viruses aggregate less than the untransformed parental cells when incubated in growth medium in a gyratory shaker for 18-24 h. This difference can be measured by electronic particle counting, or by filtering aggregated suspensions of 32P-labelled cells through bolting fabric. The aggregation of transformed derivatives is not enhanced by the presence, during aggregation of epsilon-amino caproic acid, an inhibitor of plasmin activation. Some lines of transformed BHK21 cells do not appear less adhesive than untransformed cells in a short-term aggregation assay, and none adheres markedly less well when seeded onto homotypic cell sheets. The decreased aggregation of transformed cells is consistent with suggestions that LETS protein is involved in intercellular adhesion of fibroblasts as well as in attachment of cells to non-cellular substrates. If so, the short-term aggregation of freshly trypsinized cells may depend on secretion of LETS from an intracellular pool.

Aminocaproates↗
PubMed1988

Mitogenic effects of thyrotropin and adenosine 3',5'-monophosphate in differentiated normal human thyroid cells in vitro.

Previous studies of human thyroid cells in culture (mostly from pathological tissues) failed to demonstrate a mitogenic effect of TSH, leading to the proposal that the growth effect of TSH in vivo might be indirect. To reexamine the influence of TSH on DNA synthesis and cell proliferation, we established primary cultures of normal thyroid tissue from nine subjects. When seeded in a 1% serum-supplemented medium, thyroid follicles released by collagenase/dispase digestion developed as a cell monolayer that responded to TSH by rounding up and by cytoplasmic retraction. When seeded in serum-free medium, the cells remained associated in dense aggregates surrounded by few slowly spreading cells. In the latter condition, the cells responded to TSH and other stimulators of cAMP production, such as cholera toxin and forskolin, by displaying very high iodide-trapping levels. Exposure to serum irreversibly abolished this differentiated function. TSH stimulated the proliferation (as shown by DNA content per culture dish) of 1% serum cultured cells (doubling times were reduced from 106 to 76 h) and increased by 100% the [3H]thymidine labeling indices. In serum-free cultured cells (dense aggregates or cell monolayers after initial seeding with serum), control levels of DNA synthesis were lower, and up to 8-fold stimulation of DNA synthesis occurred in response to 100 mU/L TSH (stimulation was consistently detected with 20 mU/L), based on measurements of [3H]thymidine incorporation into acid-precipitable material and counts of labeled nuclei on autoradiographs (up to 40% labeled nuclei within 24 h). The mitogenic effect of TSH required a high insulin concentration (8.3 X 10(-7) mol/L) or a low insulin-like growth factor I concentration. The mitogenic effects of TSH were mimicked in part by cholera toxin, forskolin, and dibutyryl cAMP. Epidermal growth factor and phorbol myristate ester also stimulated thyroid cell proliferation and DNA synthesis, but they potently inhibited TSH-stimulated iodide transport. We conclude that TSH, acting at least in part through cAMP, is a potent growth factor for human thyroid cells and thus provide an experimental basis in vitro for the well established in vivo goitrogenic action of TSH.

Adenosine Monophosphate↗
PubMed1986

The effect of monosodium urate on the capacity of urine, chondroitin sulphate and heparin to inhibit calcium oxalate crystal growth and aggregation.

In order to investigate the possibility of interaction between urinary glycosaminoglycans and particulate monosodium urate, growth and aggregation rates of calcium oxalate seed crystals were measured in the presence of heparin, chondroitin sulphate and normal urine after preincubation with and without monosodium urate (0.5 mg./ml.). Rates of crystal aggregation in the presence of heparin and chondroitin sulphate were significantly (p less than 0.0005) increased after pretreatment with sodium urate, indicating a reduction in the inhibitory potency of heparin and chondroitin sulphate by this salt. A similar effect was observed with the rate of crystal growth in the presence of heparin (p less than 0.01). In contrast, the rate of growth in the presence of chondroitin sulphate was unaffected. Pretreatment with sodium urate had an inconsistent effect on the rate of crystal growth in the presence of 10 normal human urine samples, but significantly (p less than 0.001) raised the rate of crystal aggregation. It was concluded that the influence of urate on crystal aggregation in the presence of urine may be a result of its binding to endogenous chondroitin sulphate, but may not be of practical consequence in the pathogenesis of calcium oxalate renal stones.

Calcium Oxalate↗
PubMed1987

In vitro culture and labeling of neural cell aggregates followed by transplantation.

Septal, cortical, or whole brain fetal (E15-17) cells were dissociated and cultured in serum-supplemented Dulbecco minimum essential medium under rotating culture conditions. Preincubation and exposure to cytosine arabinoside was utilized to produce "neuron-rich" cultures. Fluorescent latex microbeads were added to cultures at seeding time or early after aggregate formation. All cell types were found to incorporate the fluorescent beads, although apparently not to the same extent. Two- to five-day-old aggregates tended to attach and grow neurites after their transfer to poly-l-lysine- or Matrigel-coated dishes under stationary conditions. Early aggregates transplanted to the hippocampus of adult rats developed into identifiable grafts, with fluorescent-labeled cells. We conclude that "young" neural cell aggregates maintain their ability to undergo two basic phenomena for cellular interaction, i.e., attachment and neuritic growth. Floating aggregates may provide a convenient cellular condition whenever culturing of neural cells is to be used before grafting them into a host animal.

Animals↗
PubMed1988

[Inhibitory effect of CG-120 on the formation, growth and aggregation of calcium oxalate crystals in vitro].

The inhibitory effect of CG-120 on the formation, growth and aggregation of calcium oxalate (CaOx) crystals was estimated by the use of Coulter counter TA II in the whole urine system and seed crystal method. In the whole urine system, after determining the metastable limit, the formation and growth of calcium oxalate crystals precipitated in response to a load of sodium oxalate was measured. CG-120 had a strong inhibitory effect on the formation and growth above the concentration of 500 micrograms/ml. In the seeded crystal system, inhibitory activity of aggregation (Ia) and growth (Ig) were calculated from the change in the number and volume of crystals. Above 250 micrograms/ml, CG-120 inhibited the aggregation and growth of added CaOx monohydrate and dihydrate crystals. CG-120 therefore might be useful for treating the recurrent stone formers.

Calcium Oxalate↗