Inductive Factors Research Articles

A cell culture model of the blood-brain barrier.

Endothelial cells that make up brain capillaries and constitute the blood-brain barrier become different from peripheral endothelial cells in response to inductive factors found in the nervous system. We have established a cell culture model of the blood-brain barrier by treating brain endothelial cells with a combination of astrocyte-conditioned medium and agents that elevate intracellular cAMP. These cells form high resistance tight junctions and exhibit low rates of paracellular leakage and fluid-phase endocytosis. They also undergo a dramatic structural reorganization as they form tight junctions. Results from these studies suggest modes of manipulating the permeability of the blood-brain barrier, potentially providing the basis for increasing the penetration of drugs into the central nervous system.

Lens formation from the cornea following implantation into hindlimbs of larval Xenopus laevis: The influence of limb innervation and extent of differentiation

Corneal fragments of larval Xenopus laevis at stage 48 (according to Nieuwkoop and Faber, '56), were implanted into sham denervated unamputated hindlimbs, denervated unamputated hindlimbs, amputated and sham denervated hindlimbs, and amputated and denervated hindlimbs of larvae at stages 52 and 57. The results show that unamputated limbs at stage 52, either innervated or denervated, manifest a weak capacity to promote the first lens-forming transformations of the outer cornea. This capacity is absent in both limb types at stage 57. After amputation, limbs of both early and late stages form a regenerative blastema and support lens formation from the outer cornea. Denervation of early stage limbs has no appreciable effect on blastema formation and lens-forming transformation of corneal implants. However, denervation of late stage limbs inhibits both processes. These results indicate that the limb tissues of the early stage limbs contain non-neural inductive factors at a low level and that after limb amputation and blastema formation the level of these factors becomes high enough to promote lens formation from implanted cornea, even after denervation. In contrast, the limb tissues of late stage limbs do not contain a suitable level of non-neural inductive factors.

Some aspects on the biotrophy of VAM fungi

Hyphal growth from germinating spores of Gigaspora margarita was monitored under several conditions: with or without roots, root colonization, or removal of the spore. The results indicate that roots stimulate fungal growth by different mechanisms. Before colonization, roots provide inductive factors which promote fungal growth when the nutrients in spores are available. When colonization is completed, the roots also provide nutrients. The inductive action of roots probably involves root exudates and particularly gas balance, in which CO 2 appears to play key role. Any attempts to cultivate VAM fungi in pure culture should consider the nutritional and inductive role of roots.

Sex determination in the germ line of Drosophila depends on genetic signals and inductive somatic factors.

We have analyzed the mechanism of sex determination in the germ line of Drosophila by manipulating three parameters: (1) the ratio of X-chromosomes to sets of autosomes (X:A); (2) the state of activity of the gene Sex-lethal (Sxl), and (3) the sex of the gonadal soma. To this end, animals with a ratio of 2X:2A and 2X:3A were sexually transformed into pseudomales by mutations at the sex-determining genes Sxl (Sex-lethal), tra (transformer), tra-2 (transformer-2), or dsx (double-sex). Animals with the karyotype 2X;3A were also transformed into pseudofemales by the constitutive mutation SxlM1. The sexual phenotype of the gonads and of the germ cells was assessed by phase-contrast microscopy. Confirming the conclusions of Steinmann-Zwicky et al. (Cell 57, 157, 1989), we found that all three parameters affect sex determination in germ cells. In contrast to the soma in which sex determination is completely cell-autonomous, sex determination in the germ line has a non-autonomous component inasmuch as the sex of the soma can influence the sexual pathway of the germ cells. Somatic induction has a clear effect on 2X;2A germ cells that carry a Sxl+ allele. These cells, which form eggs in an ovary, can enter spermatogenesis in testes. Mutations that cause partial loss of function or gain of function of Sxl thwart somatic induction and, independently of the sex of the soma, dictate spermatogenesis or oogenesis, respectively. Somatic induction has a much weaker effect on 2X;3A germ cells. This ratio is essentially a male signal for germ cells which consistently enter spermatogenesis in testes, even when they carry SxlM1. In a female soma, however, SxlM1 enables the 2X;3A germ cells to form almost normal eggs. Our results show that sex determination in the germ line is more complex than in the soma. They provide further evidence that the state of Sxl, the key gene for sex determination and dosage compensation in the soma, also determines the sex of the germ cells, and that, in the germ line, the state of activity of Sxl is regulated not only by the X:A ratio, but also by somatic inductive stimuli.

Effect of the side chain on the racemization of amino acids in aqueous solution

The rate of racemization of 13 amino acids possessing hydroxy, carboxy, alkoxy, carboalkoxy, alkyl, aryl, and thioether side chains were compared. Reaction conditions were identical for all amino acids studied. The differences in the racemization rates with changes in the R group are discussed in terms of several factors, including intramolecular reactions, direct field effects, orbital overlap, and solvation effects, as well as inductive, resonance, and steric factors

Ultrastructure of a new generation of odontoblasts in grafted coronal tissues of mouse molar tooth germs

Third molar tooth germs were removed from 14-day-old mice and freed from the enamel organ and follicle. After section of the apical tissues, including Hertwig's sheath, they were transplanted in 1-day-old newborn mice of the same lineage. Electron microscopy of grafts removed 7, 14 and 21 days later showed that, following the disappearance of the initial layer of odontoblasts and a period of adaptation, 14 days after transplantation newly differentiated odontoblasts deposited tubular dentine. The dentine matrix production was increased over that of controls, demonstrating that synthesis was accelerated, possibly because of lack of nerves in the grafts. Numerous characteristic structures that might be involved in the transit of proteoglycans from the Golgi apparatus were seen, as far as the extremity of the odontoblast processes. The particular experimental conditions allowed the observation in the neck region of the odontoblast of a concentration of coated vesicles which might be involved in cellular lengthening. Thus, in the presence of a fine and regular vascular network, a new generation of odontoblasts may differentiate, even in the absence of epithelial and nervous elements, and so predentine may contain inductive factors that allow the odontoblastic differentiation of pulp cells in contact with it.

Alkoxycarbonyl group relaxation of some aliphatic esters in glassy media

Dielectric absorption studies have been made in the frequency range 10 2–10 5 Hz of a variety of aliphatic esters of the type R 1COOR 2; where the size, steric and inductive factors are varied. The esters have been studied in glassy media. An intramolecular relaxation process around the R 1XXX(COOR 2) bond in vinyl propionate, vinyl butyrate, vinyl chloroacetate and vinyl bromoacetate has been observed in the 79–133 K region with a very low Eyring enthalpy of activation. The barrier is appreciably less than that for alkoxy (-OR 2) group rotation, and is fairly insensitive as to whether R 1 is an alkyl or halo-substituted alkyl group. Further, the barriers (2–9 kJ mol −1) are comparable to the theoretically calculated value of 5.5 kJ mol −1, and the speculation in the literature that the barrier for rotation of the alkoxycarbonyl group [in poly(methylmethacrylate)] may be substantially enhanced in a matrix is not borne out for the relatively smaller molecules examined here.

Immunoregulation of murine plasmacytoma. II. Target selectivity of anomalous killer cells and role of immune T cells for the induction.

Requirements for the induction of anomalous killer (AK) cells to syngeneic MOPC 104E-KI81 plasmacytoma, and their pattern of reaction were investigated. The AK cells are Thy-1.2 positive and were induced by cocultivation of normal BALB/c spleen cells for 5 days in vitro with mitomycin C-treated MOPC 104E-KI81 cells in RPMI 1640 medium supplemented with fetal calf serum and 2-mercaptoethanol. The pattern of reactivity was investigated by direct cytotoxicity and indirect cold target inhibition assays using a panel of target cells. The results from cold target inhibition show that anomalous killer cells react with various tumor targets in the same preferential order as the results shown in direct cytotoxicity assay, and indicates that the AK cell population may be detecting the same determinants expressed to different degrees on panels of target cells. Kinetic study showed that peak cytotoxic responses were observed on day 5 and day 4, for primary and secondary sensitizing cultures, respectively. Cytotoxicity was not generated when nude mouse spleen cells were used as responder cells, suggesting the essential role of T cells in the induction. Nylon wool-column-purified splenic T cells from mice primed in vivo with intraperitoneal injection of MMC-treated stimulator cells, but not from normal mice, were able to generate AK cells in vitro. These results indicate that generation of AK cells with NK-cell-like reactivity needs inductive factors provided by the immune reaction between sensitized T cells and stimulatory MOPC 104E-KI81 cells.

Demonstration of reduced mitogenic and osteoinductive activities in demineralized allogeneic bone matrix from vitamin D-deficient rats.

Osteoinduction is the formation of ectopic bone that follows implantation of demineralized allogeneic bone matrix (DABM) and is believed to be secondary to the release of associated inductive factors from bone matrix. To clarify the role of vitamin D in osteoinduction, we implanted DABM from vitamin D-deficient rats (-D rats) into normal rats (+D rats). Because mitogens and osteocalcin might be involved in osteoinduction, these were measured. Mitogenic activity in extracts from mineralized allogeneic bone matrix (ABM) and DABM from both +D and -D rats was determined with an assay that utilizes monolayer cultures of embryonic chick calvarial cells. Osteocalcin in serum and DABM was measured by radioimmunoassay. DABM from -D rats did not promote osteoinduction as effectively as DABM from +D rats. Resorption of implant matrix from -D rats was diminished compared with resorption of matrix from +D rats (P less than 0.01), and the decrease was attributed to a corresponding decrease in the number of osteoclasts in the implants (P less than 0.02). Bone formation (P less than 0.01) and total implant mineralization (P less than 0.001) were significantly reduced in implants from -D rats, and the reductions corresponded with a decline in the number of osteoblasts (P less than 0.05). Mitogenic activity in DABM from +D rats was only slightly decreased as compared with activity in ABM, but DABM from -D rats contained significantly less activity (P less than 0.001). No mitogenic activity was identified in implants of DABM from either +D or -D rats 3 wk after implantation. Serum osteocalcin was significantly higher in -D as compared with +D animals. In contrast, the concentrations of osteocalcin in DABM from the two groups of animals were not significantly different from each other. These findings indicate that the diminished osteoinductive activity of DABM from -D rats results from deficiency of one or more mitogenic factors that are essential for inducing the proliferation and differentiation of bone cells at the implant site and that osteocalcin does not play a role in this regard.

Effects of relative humidity, oxygen, and carbon dioxide on initiation and early development of stolons and tubers

Russet Burbank potatoes were grown in the greenhouse to explore the effects of soil O2, CO2, and relative humidity on tuberization. The composition of the gas phase surrounding the below ground stem and stolons was controlled at various levels. Prolonged levels of CO2 greater than 5% produced large lenticels and, in combination with high relative humidity suppressed the number of stolons. Oxygen levels of 5% or less in prolonged contact with the stolons and underground portion of the stem were favorable to stem decay by pathogens but did not affect lenticel size. Isolating the stolons in a low relative humidity environment delayed tuber set, but increased the number of tubers per plant. This effect of low humidity suggests that the onset of tuberization involves at least two inductive factors, one of which is not translocated among stolons.

Effect of ínductive photoperiod and gibberellin treatment on peroxidase enzyme system in relation to floral induction inImpatiens balsamina L

Gibberellins A3 and A13 cause floral induction inImpatiens balsamina, a qualitative short day plant, under non-inductive 24-h photoperiods (continuous illumination). However, the influence of the two inductive factors,i.e. gibberellins and short days (8-h photoperiods) on the peroxidase enzyme system is different. The total peroxidase activity decreases under both inductive and non-inductive photoperiods, with or without gibberellin treatment. The electrophoretic pattern of isoperoxidases changes only in response to gibberellin treatment. Under 24-h photoperiods, treatment with gibberellins A3 and A13 causes the appearance in the stem of three additional isoenzymes of peroxidase (Rm 0.50, 0.71 and 0.76). These bands do not appear in the leaves, which are non-essential for gibberellin-caused floral induction in this plant. Under 8-h photoperiods also, gibberellins induce the appearance of new isoenzyme bandsi.e. two in the stem (Rm 0.50 and 0.76) and one in the leaves (Rm 0.05). These may be correlated with the synergistic increase in the number of floral buds in these plants in response to simultaneous exposure to two inductive factors.

Substituent effects on 1H NMR spectra of 4‐and 4′‐substituted tras‐N‐benzylideneanilines in acidic solution

AbstractVarious 4‐ and 4′‐substitued trans‐N‐benlizylidenanilines were synthesized and their 1H NMR spectra recorded at 30 °C in DMSO‐d6, and acidic media (TFA‐d and D2SO4). The effects of substituents on the chemical shifts of H‐α (proton on carbon of imine group) and H‐2′ (protons on benzaldehyde ring ortho to the imine group) were analysed by the Hammett single parameter and Taft dual substituent parameter (DSP) techniques. In the neutral solvent DMSO‐d6, there is transmission of the electronic effects of substituents on the benzaldehyde ring to the H‐α and H‐2′ protons, but no electronic transmission for substituents on the aniline ring. There is a dramatic change in acid media. Protonation of the imine group results in significant electronic transmission from substituents on the aniline ring to the H‐α and H‐2′ protons, as well as an enbancement in electronic transmission from substituents on the benzaldehyde ring. DSP analysis indicates that both inductive and resonance factors are responsible for the observed electronic transmission effects, with resonance being the major factor.

Spring bloom in a hypereutrophic lake, Lake Kasumigaura, Japan—IV: Inductive factors for phytoplankton bloom

The limiting factor for inducing the spring bloom of phytoplankters in 1980 at Tsuchiura Harbor of Lake Kasumigaura was shown to be temperature. The bloom started at a water temperature higher than 10°C and lasted until the temperature was up to approx. 20°C. The concentration of inorganic nitrogen in the lake was found to have a profound effect on the induction of the spring bloom as a nonlimiting factor. Other inorganic nutrients contributed mostly to the species succession of phytoplankters comprising the spring bloom.

Preparation and Diels‐Alder Reactivity of Tricarbonyliron Complexes of [2.2.2]Hericene

AbstractTreatment of [2.2.2]hericene 10 with Fe2(CO)9 in hexane gave a mixture of monometallic complex 14, two isomeric dimetallic complexes 15 and 16, and a trimetallic complex 19 in which all the three diene moieties of 10, are coordinated. The rate constants of the Diels‐Alder additions of tetracyanoethylene (TCE) and dimethyl acetylenedicarboxylate (DMAD) to the uncomplexed diene moieties of 14–16 have been evaluated and compared with those measured for the uncomplexed 10 and its monoadducts 11A, 11B and bis‐adducts 12A, 12B. The tricarbonyldieneiron function retards the cycloaddition of an homoconjugated, exocyclic s‐cis‐butadiene. The effect is significantly larger for TCE‐ than for DMAD‐additions. The origin of this effect is discussed briefly in terms of the valence‐bond model which is usually assumed to describe the properties of a tricarbonyldieneiron complex, and in terms of the inductive and steric factors of the Fe(CO)3‐group.

Osteochondrogenesis of free periosteal grafts in the rabbit iliac crest.

The influence of the bone marrow, cortical bone and apophyseal cartilage of the iliac crest on osteochondrogenesis from free autogenous periosteal grafts was studied histologically in 8-week-old rabbits. Tibial periosteum was transplanted around the iliac crest, from which the periosteum had been removed from the inner side, periosteum and cortical bone in an area on the outer side and perichondrium from the apophyseal cartilage. Most bone formation occurred in the area with periosteum in contact with the bone marrow of the cancellous bone. By means of an isolating Nucleopore filter, it was revealed that the most vigorous of this bone formation originated from the periosteal graft. Further, it was noted that in the series with the Nucleopore filter, bone formation was slower than in the series without the filter, suggesting some inductive factors. No bone formation occurred in the apophyseal area.

Synovial factors and chondrocyte-mediated breakdown of cartilage: inhibition by hydrocortisone.

Cartilage-synovium interactions were explored in a model culture system. Bovine nasal-cartilage discs were cocultured with minced rheumatoid synovium or synovium-conditioned media (SCM) in the presence or absence of hydrocortisone. Cartilage breakdown was assessed by the release of proteoglycan (PG) and hydroxyproline, and matrix biosynthesis by [35S]sulfate incorporation during pulse labeling. Chondrocyte-dependent breakdown in response to synovial factors (i.e., "catabolin" activity) was assessed by the difference in PG release between living and dead cartilages. Short-term contact with minced synovial membrane or exposure to its products released at a distance was sufficient to induce cartilage degradation in coculture; continued exposure was not required for breakdown to persist. Conditioned media from short-term synovial culture were similarly potent, and the induced breakdown was chondrocyte dependent. Matrix biosynthesis was inhibited in exposed cartilage but could be rapidly restored to normal on synovium removal despite the persistence of cartilage breakdown. Early hydrocortisone treatment suppressed the initiation of cartilage breakdown in cocultures and largely abolished the appearance of inductive factors in SCM. Later applications had little effect either in cocultures or in catabolin assays. We conclude that synovium-induced breakdown is an early event and that chondrocyte catabolic mechanisms once they have been activated are sufficient to maintain breakdown at a high level. Hydrocortisone, as well as limiting proteolysis, inhibits early tissue interactions at the level of synovial catabolin production or release.

Effects of Severe Calorie Restriction on Thymic Factor Activity and Lymphocyte Stimulation Response in Rats

The thymic factor (TF) activity and lymphocyte stimulation response to phytohemagglutinin (PHA) was studied in calorie-restricted rats. Sprague-Dawley rats (28 days old) were fed a calorie-restricted diet (30% of the average food intake of control) for 4 weeks. The control group was allowed food ad libitum. After this period the body weight was 232.9 +/- 41.8 g for control rats and 66.1 +/- 4.5 g for the calorie-restricted group. The mean thymus weight was 0.699 +/- 0.153 g and 0.099 +/- 0.030 g for the control and experimental groups respectively. The TF activity was makedly reduced in the calorie-restricted group compared with the control. There was an overlap between lymphocyte stimulation responses of the two groups; however, the mean number of counts per minute (cpm) of stimulated cultures with PHA was lower and the mean cpm of unstimulated cultures without PHA was higher in the starved animals. Thus, the stimulation index was significantly lower in the deprived rats. It is suggested that deficiency of thymic inductive factors may be important in the pathogenesis of impaired cell-mediated immunity in nutritional deficiency states.

The induction of lysosomal enzyme activity in the fat body of Calliphora erythrocephala: Changes in the internal environment

The activity of the lysosomal marker enzyme acid phosphatase in the larval fat body of Calliphora erythrocephala increases during development, but not at the same rate throughout the tissue. During the feeding stage, the posterior region has a higher acid phosphatase activity than the anterior region. When the larvae cease feeding on the 5th day of development, the acid phosphatase activity of the inactive anterior lobe increases rapidly in a mosaic-cell pattern. When 4-day-old feeding stage larvae are starved, this increase occurs one day earlier than normally. After the emptying of the gut, the acid phosphatase activity of all the anterior cells both in normal and in starved larvae exceeds that of those in the posterior region. Transplantation experiments indicate that the induction of acid phosphatase activity in the fat body during normal development, especially in the anterior region, is caused by a change in the internal environment when the larvae cease feeding. Both RNA and protein synthesis are involved in this induction process. Inductive factors are present in 5-day-old larvae as well as during formation of the puparium. The competence of the feeding-stage fat cells to develop high acid phosphatase activity is acquired before the actual induction takes place.

The role of macrophages in stimulation of immune induction and myelopoiesis. I: Comparison of activity of macrophage-derived factors in granulopoiesis and immunostimulation

Hemopoietic growth and immunological inductive factors from human peripheral leukocyte conditioned medium and mouse macrophage culture supernatant fluids were compared. Factors derived from human peripheral leukocyte conditioned medium were found to substitute for those of mouse macrophage derivation in immunological assays, namely, induction of a cytotoxic T-lymphocyte response in macrophage-depleted mouse spleen cultures. Association of macrophage-derived factors with β2-microglobulin (β2m) antigen determinants was observed by inhibition with goat antihuman β2m, affinity chromatography, and direct replacement of mouse macrophage-derived factors with human urinary β2m.

Effects de la substitution du cycle pyrrolidone‐2 par un groupement méthyle sur le processus de polymérisation

AbstractWe tried to evaluate the reason for the very low polymerizability of methyl derivatives of 2‐pyrrolidone in the presence of anionic polymerization catalysts. The polymerizability estimated from the influence of the methylated group on the reactivity of the lactam ring (steric, inductive, and thermodynamic factors) does not agree with the experimental results of homopolymerization and copolymerization of 2‐pyrrolidone. The substitutional effects on the propagation process were analyzed and an explanation which is based on the slow‐down of the molecular growth and the crystallization of the reaction mixture is proposed. Thus, in copolymerizations with a small percentage of substituted lactams, the propagation is very slow with regard to the crystallization, which would allow a quick encagement of the active site by hydrogen bonds, and lead to the spontaneous blocking of polymerization. If this percentage increases, the crystallization cannot take place, and this would, as a consequence. favor all the secondary reactions leading to the formation of bicyclic dimer and oligomers.A “chain multiplication” reaction was found in some cases.