Growth-inhibiting Substances Research Articles

Antineoplastic agents. 278. Isolation and structure of axinastatins 2 and 3 from a western Caroline Island marine sponge.

The Republic of Palau marine sponge Axinella sp. was found to be an exceptionally productive source of cell growth inhibitory substances. The strongly antineoplastic polyether macrocyclic lactones halichondrin B (1) and homohalichondrin B (2) were isolated in 1.2 x 10(-6)% and 5.4 x 10(-7)% yields, respectively. In addition to axinastatin 1 (3), two new and cytostatic (GI50 values of 0.35 to 0.0072 microgram/mL against six human cancer cell lines) cycloheptapeptides designated axinastatins 2 (4) and 3 (5) were discovered in 1.4 x 10(-6)% and 1.25 x 10(-6)% yields. Structures were elucidated by high-resolution FABMS and tandem MS/MS techniques augmented by high-field (400 and 500 MHz) 2D-NMR spectral analyses. The absolute configurations were established by a combination of hydrolysis, derivatization, and chiral gas chromatographic methods.

Mechanism of an early lysis by fatty acids from axenic Phormidium tenue (musty odor-producing cyanobacterium) and its growth prolongation by bacteria.

We have previously demonstrated that bacteria-containing Phormidium tenue, a cyanobacterium which produces musty odor 2-methylisoborneol, grew beyond 8 weeks, whereas axenic alga perished suddenly between the 3rd week and the 4th week while being cultured in the laboratory. This mechanism was investigated. It is assumed that when algal cells grow beyond a certain level, the supply of CO2 becomes inadequate and results in the rapid lysis of axenic alga. At that time, inhibitory substances liberated from algal cells kill the surviving alga. Since the process occurs continuously, this alga is finally annihilated. On the other hand, since inhibitory substances are metabolized or degraded by bacteria coexistent with alga, bacteria-containing P. tenue maintains growth for a long time. The growth-inhibitory substance was found to be unsaturated free fatty acids.

Effect of Benomyl on Seedling Rot of Rice(Pseudomonas glumae) and Microbial Interactions on Germinating Rice Seeds.

Pseudomonas glumae grew on potato-dextrose agar plates containing benomyl at the concentration of 500 to 1, 000μg/ml depending on the strains, but not at 1, 500μg/ml. The growth inhibition resulted from bacteriostatic action of the chemical. Cultures of the bacterium contained benomyl-resistant mutants at various frequencies depending on the strains. Virulence of these mutants was identical to that of the parent strains. Regardless of the presence of such resistant mutants, seedling rot of rice was effectively controlled by seed-dressing with 0.1% (w/w) benomyl or 0.5 to 1.0% Benlate or Benlate-T. Such suppressive effect was not observed when sterilized rice grains were used. The population of P. glumae was significantly suppressed on benomyl-treated seeds, but rapidly increased on untreated seeds. On the contrary, saprophytic bacteria, particularly fluorescent pseudomonads, substantially increased on benomyl-treated seeds, but not on untreated seeds. The fluorescent pseudomonads inhibited growth of P. glumae in vitro and significantly suppressed development of seedling rot in situ as well. They were identified as P. fluorescens and the production of growth inhibitory substances was confirmed in liquid media. These observations suggested that the efficacy of benomyl against seedling rot of rice resulted mainly from the antagonistic effect of P. fluorescens which preferentially proliferated on the benomyl-treated seeds.

Induction of Tomatine in Tomato Plant by an Avirulent Strain of Pseudomonas solanacearum.

Tomato plants inoculated with an avirulent strain of Pseudomonas solanacearum (strain Str-10 op type) produced a growth inhibitory substance at a higher level than those of uninoculated control in root system but not in stem. The substance was identified to be tomatine by Mass Spectrometry, TLC, UV spectrometry and chemical component analysis. The tomatine contents five days after inoculation were 113 and 152μg/g fresh root when Str-10 op type was inoculated at the inoculum concentrations of 108 and 109cfu/ml, respectively. Tomatine content in the uninoculated control plants was 65.9μg/g. Tomatine content nine days after inoculation reached 450μg/g. In an in vitro experiment, 100μg/disk of authentic tomatine and approximately 150μg/disk of extracted tomatine were sufficient for growth inhibition of P. solanacearum. Both extracted and authentic tomatine exhibited bacteriostatic activity against P. solanacearum. Treatment with heat-killed cells or culture filtrate of Str-10 op type failed to increase tomatine content in the root tissue.

Role of endothelium in ischemic coronary syndromes

The recent discovery that the endothelium synthesizes several powerful vasodilators, including prostacyclin and endothelium-derived relaxing factor, has substantially changed our view of the importance of the vascular endothelium and the perspective from which we consider the mechanisms of vascular control. It Is now known that the vascular endothelium plays a key role in circulatory homeostasls through its ability to sense the local vascular milieu and respond to it by the synthesis and release of a variety of biologically active substances. The endothelium influences not only vascular tone, but also vascular remodeling via the production of growth-promoting and growth-inhibiting substances; hemostasis and thrombosis through antiplatelet, anticoagulant, and fibrinolytic effects; and inflammation through the expression of chemotactic and adhesion molecules on the cell membrane. In diseases such as atherosclerosis, however, these functions of the endothelium are impaired and may even become counterproductive and disease-promoting. The “activated” or injured endothelial cells paradoxically become prothrombotic, growth-promoting, and leukocyte-adhesive. The endothelium also loses its vasodilating ability, rendering the underlying vascular smooth muscle susceptible to a preponderance of vasoconstrictive forces. It is now recognized that these disturbances in endothelial function are principal players in the ischemic manifestations of coronary artery disease. Endeavors to modify or reverse endothelial dysfunction may therefore be of significant therapeutic benefit in the treatment of myocardial ischemia. This review outlines several important insights into the biology of the arterial wall that are currently being applied to the study of coronary artery disease in humans.

Cell kinetics of normal and healing rat corneal epithelium during organ culture.

Local epithelial proliferation in corneal, limbal, and conjunctival rat epithelium was investigated during organ culture of corneo-scleral shells, by relating the number of tritium labelled cells to the total number of cells (labelling index). The changes in labelling index after a mechanically induced central corneal abrasion were also studied. Local labelling indices were measured 2 h, 1, 2, 4 and 7 days after incubation. The average labelling index increased in un-abraded specimens 4-fold after 4 days of incubation, while the total number of cells only decreased 30-50%. In eyes with a central corneal abrasion the labelling index increased 10-fold in the surrounding epithelial cells after 1 day. The labelling index of the limbal and conjunctival epithelial cells increased to the same extent after 2 days of incubation. The finding of a reduced total number of cells and an increased cell proliferation in un-abraded eyes may be explained by increased loss of mature cells normally producing growth-inhibitory substances (chalones). Alternatively, the culture medium may contain an excess of growth-stimulatory substances. The results also suggest that the proliferative response spreads in a centrifugal direction during in vitro healing of a central corneal abrasion.

Interleukin 4 potentiates the antiproliferative effect of 1α,25-dihydroxyvitamin D 3 on mouse monocytic leukemia cells but antagonizes the antiproliferative effects of interferon α,β and interleukin 6

Mouse monocytic leukemia Mm cells are a line of spontaneously differentiated cells obtained from mouse myeloblastic leukemia M1 cells. The effect of interleukin 4(IL-4) an the proliferation of Mm cells in the presence or absence of growth inhibitory substances was investigated. In semi-solid agar culture, IL-4 markedly inhibited colony formation by Mm cells, reducing the number of colonies to 50% of that in control cultures at concentration of 3 U/ml. In contrast, IL-4 did not inhibit colony formation by the parent Ml cells. In liquid culture, IL-4 alone inhibited the proliferation of Mm cells only slightly. However, a combination of IL-4 and 1α,25-dihydroxyvitamin D 3 (VD3), which alone did not inhibit growth significantly, markedly inhibited the growth of Mm cells. This combination also increased the lysozyme activity of Mm cells significantly. Ort the other hand, IL-4 suppressed the antiproliferative effects of interferonα,β and IL-6, which are growth inhibitory cytokines for these Mm cells. These results indicate that IL-4 can modulate the growth of monocytic leukemia Mm cells and that its modulatory effects depend an growth inhibitory substances.

Growth of peach as affected by decomposition of own root residues in soil

The effects of decomposing peach root residues in soil on peach growth were determined in two pot experiments. In the first, peach root residues, despite their high C:N ratio and lignin content, largely decomposed under experimental conditions, leading to an immobilization of inorganic N. Shoot growth of peach seedlings was depressed by the addition of peach root residues, an effect that depended on their size and concentration: fine-textured root fragments (0.45–1.00 mm) resulted in more severe effects than medium sized ones (2–8 mm), while growth depression occurred only at concentrations higher than 0.35%. Peach root growth was depressed by root residues regardless of their size and amount. In the second experiment, where nitrogen was added to all pots to minimize the effects of immobilization of N during decomposition of root fragments, the growth of peach roots in residue-supplemented soil almost stopped. Pre-planting phosphate enrichment was very effective in stimulating growth of peach in virgin soil but did not offset the depression caused by peach root residues. It thus appears that besides mineral deficiencies, there exist alternative explantations of poor growth of peach in replant soils, including growth-inhibiting substances from decomposing root residues.

Early molecular response to rabbit bladder outlet obstruction

AbstractPartial obstruction of the rabbit bladder outlet induces a rapid hypertrophy characterized by increased bladder weight and smooth muscle content in addition to increased collagen deposition. In experiments designed to examine the genetic basis of this response, we evaluated the expression of a multitude of gene products in the rabbit bladder during the first 48‐hr period following placement of a urethral cuff blocking the rabbit bladder outlet by 90%. Individual bladders were obtained from unoperated rabbits, from sham‐operated rabbits and from rabbits at 2, 6, 10, 24, and 48 hr after obstruction. Poly (A)+ mRNA was extracted from each of these tissues and Northern blots made from the RNAs were hybridized repeatedly with a series of probes. Corrected densitometry was utilized to assign a value to each transcript and to follow the change in expression of a given gene product over time.Although several of the gene products we analyzed for were undetectable or unchanged over this brief period, we were able to detect a substantial sustained increase in the 4.5 kb mRNA encoding basic fibroblast growth factor (bFGF) initiated by 2 hr after obstruction. Later, at 6–24 hr, we measured transient induction of transcripts encoding c‐myc, heat shock 70K (hsp‐70), Ha‐, and N‐ras. In contrast, the constitutively‐expressed 2.4 kb transcript for transforming growth factor‐β (TGF‐β) transiently declined to 50% of control levels at 24 hr following obstruction. In summary, our results provide a picture of tissue in transition, with synthesis of certain growth‐stimulating and stress‐response products (bFGF, myc, ras, and hsp‐70) increasing and a growth‐inhibitory substance (TGF‐β) decreasing. © 1992 Wiley‐Liss, Inc.

Purification and Properties of Growth Inhibitor from Normal Rabbit Serum1

It was previously found that rabbit serum contains a growth-inhibitory substance for a tumorigenic rat liver cell line RSV-BRL. In the present study, the growth inhibitor was purified from normal rabbit serum to show a homogeneous protein band with a molecular weight (Mr) of 56 k on SDS-polyacrylamide gel electrophoresis under non-reducing conditions. The purified growth inhibitor, tentatively named rabbit serum-derived growth inhibitor (RSGI), potently inhibited the growth of RSV-BRL and nine kinds of other cell lines including three human tumor cell lines at a concentration of 20 ng/ml or higher. The growth-inhibitory effect of RSGI was reversible and appeared to be cytostatic rather than cytotoxic. RSGI was stable to heating at 56 degrees C for 30 min or treatment with 0.1 M 2-mercaptoethanol, but labile to heating at 100 degrees C for 3 min or treatment with 1 M acetic acid (pH 2.3), 6 M urea, 50% (v/v) 1-propanol, or 0.1% (w/v) trypsin. These properties of RSGI suggested that it was different from type beta transforming growth factors, tumor necrosis factor-alpha, and other known growth-regulatory factors.

The Ecological Impact of Allelopathy in Ailanthus altissima (Simaroubaceae)

Compounds inhibitory to the growth of neighboring plant species were found in significant concentrations in the leaves and stems of young Ailanthus altissima ramets. The surrounding soil also contained appreciable concentrations of similarly acting toxins. Individuals of neighboring plant species have either incorporated active portions of inhibitory compounds or responded to Ailanthus by producing growth-inhibiting substances. Under greenhouse conditions, individuals of neighboring plant species previously unexposed to Ailanthus in the field were found to be more susceptible to the Ailanthus toxins than individuals previously exposed. Moreover, seeds produced by unexposed populations were also more susceptible to Ailanthus toxins than seeds produced by previously exposed populations. These differences demonstrated that the allelochemicals of Ailanthus altissima exhibited a measurable impact upon neighboring plant species. Since the progeny of these populations displayed a differential response to Ailanthus toxin, this phenotypic difference between the two populations may have a heritable basis.

Stimulation of Fibronectin Secretion in Cultured Human Keratinocytes by Transforming Growth Factor‐β Not by Other Growth Inhibitory Substances

We investigated the effects of various growth inhibitory substances on fibronectin secretion in cultured normal human keratinocytes. Fibronectin secretion in keratinocytes was expressed by two methods: immunofluorescent staining of cells with anti-human fibronectin antibody, and sodium dodecyl-sulphate-polyacrylamide gel electrophoresis of [35S]-labeled proteins secreted by the cells followed by autoradiography. With immunofluorescent staining, the extracellular fibronectin was observed as coarse fibrils only in some cells of the control culture, while cells treated with 20 ng/ml transforming growth factor-beta 1 (TGF-beta 1) showed intense fluorescences in a radiating pattern around most of the cells, indicating that TGF-beta 1 markedly increased fibronectin secretion in keratinocytes. Analysis of [35S]-methionine labeled proteins also revealed that TGF-beta 1 increased fibronectin secretion eight fold in culture medium. TGF-beta 2 has also induced weak increase of fibronectin secretion 1.8 fold in keratinocytes. In contrast, other growth inhibitory substances, such as tumor necrosis factor-alpha, 1,25-dihydroxyvitamin D3 and cyclosporin A, did not show any significant effects on fibronectin secretion. These results indicated that increase of fibronectin secretion is not associated with growth inhibitory effect, but rather with a specific effect of TGF-beta.

Growth inhibition of Acidiphilium species by organic acids contained in yeast extract

The growth of Acidiphilium species was inhibited by 0.4% yeast extract (Difco Laboratories). The growth inhibitory substances were purified from the yeast extract and identified as dl-lactic acid and succinic acid. The minimum inhibitory concentrations (MICs) of dl-lactic and succinic acids against Acidiphilium sp. 63 were 1 and 3 mM, respectively. The contents of dl-lactic and succinic acids in the yeast extracts were estimated at 43.9 and 1.2 mg/g using high-performance liquid chromatography. Acidiphilium species that we have been studying could be classified into two groups on the bases of the difference in susceptibility to these two organic acids.

Inhibitory effect of cis-dehydromatricaria ester isolated from Solidago altissima on the growth of mammalian cells.

A cell growth inhibitory substance was isolated from Solidago altissima, which is known as a naturalized weed. The data of infrared spectrum, proton and carbon-13 nuclear magnetic resonance spectrum, and mass spectrum were identical with those of cis-dehydromatricaria ester. The compound inhibited both tumor and normal mammalian cells.

Algicidal properties of a bloom‐forming blue‐green alga, Oscillatoria sp.

AbstractAn isolate of Oscillatoria from local eutrophic lake exhibits strong growth inhibitory effects, when phototrophically co‐cultured with a green alga and other blue‐green algae, including its natural predecessor. This effect was not observed on selected heterotrophic‐organisms. The characteristic interaction was also demonstrated with culture filtrates and cell‐free extracts, implying this effect to be due to some chemical released from Oscillatlia. From the mid‐log growth phase of the culture, a nonproteinaceous, moderately heat stable, and ether soluble metabolite was extracted by ether extraction. The primary site of the growth inhibitory substance (algicide) action appears to be the photosynthetic oxygen evolution, tested in Anacystis nidutlans. The characteristic algicidal substance may have a role, in nature, in species dominance.

Distribution of microflora in the intestinal tract of carp Cyprinus carpio.

The present study was undertaken to investigate the localization of microflora in the intestinal tract of carp Cyprinus carpio. Aeromonas, Enterobacteriaceae, Pseudomonas and Bacteroides type A were predominantly detected in almost all intestine segments, although they did not necessarily increase gradually during the passage of contents from the fore- to post-intestine. Furthermore, the phenomenon was found that the percentage of each aerobe/facultative anaerobe dropped and that of each obligate anaerobe raised with the increase of total viable count (TVC). No antagonistic interaction, mediating the growth-inhibiting substance, was observed between the aerobes/facul-tative anerobes and the obligate anaerobes. Therefore, the above phenomenon may be attributed to the Eh or O2 concentration in each site of intestines because the growth of obligate anaerobes and aerobes is inhibited by the O2 at high and low concentrations, respectively.

Pigeon crop-sac as a model system for studying the direct and indirect effects of hormones and growth factors on cell growth and differentiation in vivo

The pigeon crop-sac is an underappreciated and underutilized model that can be used to study the direct and indirect effects of hormones, growth factors, and other agents on cell proliferation and differentiative processes in vivo. It can thus allow the uncertainties that attend many in vitro methods to be avoided. In addition, the crop mucosal cells are homogeneous and the organ is structurally much less complex than most other hormone-responsive target organs, such as the mammary gland or prostate. The organ is well suited for various other studies such as analysis of second-messenger systems for PRL and growth factors and the effects of growth-inhibitory substances.

Regulation of lung cell proliferation by polypeptide growth factors.

In the last 10 years there has been an increased appreciation of the changes in lung cell populations that occur in association with the acute respiratory failure often induced by traumatic injury. Early events result in an accumulation in the lung of platelets, neutrophils, monocytes, and macrophages, a release of substances having potent cardiopulmonary and metabolic effects, and an ensuing edema and transudation of materials from the interstitium and capillaries into the alveoli. Further progression of the injury results in significant decreases in the number of endothelial and type I epithelial cells and a subsequent hyperplasia of fibroblasts and type II-like epithelial cells. Major sequelae of the latter stage of the disease are interstitial and interalveolar fibrosis, probably resulting from the increased number of fibroblasts present. The activity and composition of pulmonary surfactant are often perturbed. This review will discuss mechanisms that may be involved in these processes, with major emphasis on cell-cell interactions mediated through polypeptide growth factors. We describe the properties of certain growth factors commonly associated with inflammatory and wound healing reactions, discuss their cellular origins, and speculate on their possible roles in mediating the structural and physiological responses seen in the lung during acute respiratory failure. The majority of work done with lung cells has concentrated on interactions between macrophages and fibroblasts, and it is evident that macrophages are capable of producing mitogens affecting the proliferation of fibroblasts. However, from the results of studies that are less developed, it is possible that epithelial cells and immunologically stimulated cells could also be involved in these actions. We conclude that the homeostasis of lung cell populations may be influenced by both growth-stimulating and growth-inhibiting substances and potentially could involve interactions through growth factors of fibroblasts, macrophages, lymphocytes, alveolar epithelial cells, endothelial cells, and platelets. At this time the information on these purported interactions is quite limited and there are far more questions than answers.

Tissue sections from the mature rat brain and spinal cord as substrates for neurite outgrowth in vitro: Extensive growth on gray matter but little growth on white matter

The failure of axons to regenerate within the brain and spinal cord of mature mammals has been attributed to the absence of growth-promoting substances, especially extracellular matrix components, or to the presence of growth-inhibiting substances, particularly components associated with CNS myelin. The ability of mature mammalian CNS tissue to support neurite regeneration was tested by growing explants of embryonic chick lumbar sympathetic ganglia on fresh frozen sections of the mature rat brain and spinal cord. The extent of neurite outgrowth was quantified using morphometric analysis for explants grown on sections that included most of the major anatomical divisions of the CNS. Extensive, but variable, regeneration was present on gray matter regions, whereas major white matter tracts showed poor support, if any, for neurite growth. The results are consistent with the presence of growth-inhibiting factors associated with CNS white matter but also indicate that most gray matter regions of the mature mammalian brain and spinal cord will support axonal regeneration in tissue culture in spite of the absence of known extracellular matrix components.

Phototropism involves a lateral gradient of growth inhibitors, not of auxin. A review

During phototropic curvature, indolyl-3-acetic acid (IAA) remains evenly distributed in the hypocotyl of sunflower ( Helianthus annuus L.) and in the oat ( Avena sativa L.) coleoptile. At the irradiated side, growth-inhibiting substances accumulate. In sunflower, basipetal movement of a growth factor is not involved, since the top of the seedling can be covered or removed without affecting the phototropic response; this response, moreover, is independent of the rate of elongation growth. The chemical nature of the growth-inhibiting substances is only partly known. In the hypocotyl they occur in the neutral fraction: in sunflower cis-xanthoxin is one of them, in radish ( Raphanus sativus L.) cis- and trans-raphanusanins, and possibly raphanusamide, are involved. The inhibitor(s) in the oat coleoptile are acidic. During curvature, their amount remains rather constant but the distribution changes with an accumulation at the irradiated side. It is concluded that phototropic curvature is brought about by an accumulation, at the irradiated side, of growth-inhibiting substances that unilaterally reduce cell elongation even though the IAA distribution is uniform.