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PubMedDate not supplied

Cell-free wheys from bifidobacteria fermented milks exert a regulatory effect on the intestinal microflora of mice and humans.

Bacteroides fragilis and clostridia are normally present in the human colon but they may exert pathogenic effects when the homeostasis is upset following various forms of stress. One approach to preventing gastrointestinal disorders is to use bifidobacteria fermented milk. It has been suggested that the efficacy of such a product is related to abiotic compounds produced during milk fermentation. Experiments reported in this paper attempt to check this theory. Six whey retentates were prepared by fermenting cow's milk with six human strains of Bifidobacterium breve and acetic and lactic acids were eliminated by ultrafiltration. Their ability to reduce intestinal clostridial carriage was assessed in C3H mice. Only one whey retentate led to a decrease in clostridia, bacilli, B. fragilis and fecal pH and to an increase in bifidobacteria. Assays in ten human volunteers resulted in similar changes in fecal flora and fecal pH within 7 days of whey retentate intake (30 mL/day). No antibiotic-like effect was demonstrated in vitro. Compounds involved in microflora regulation were located in two ultrafiltrated fractions (30-100 and 100-300 kDa). Both fractions contained mainly low molecular weight glycoproteins (20-40 kDa) and two high molecular weight glycoproteins (121, 211 kDa) that were almost undetectable in the inactive 10-30 kDa fraction.

Journal Article↗
PubMed1996

Antisense oligodeoxynucleotides targeted against different regions of cyclin D1 mRNA may exert different inhibitory effects on cell growth and gene expression.

The alteration of cyclin D1 gene expression is a common feature of malignancies of diverse histogenesis. Our recent results showed that over expression of cyclin D1 protein is frequently found in human ovarian cancer. In this study, we investigated the effect of cyclin D1 antisense oligodeoxynucleotides on cell growth and gene expression in PA-1 ovarian cancer cells. Our results demonstrated that cyclin D1 antisense oligodeoxynucleotides indeed functioned as an antiproliferative agent. More strikingly, we found that different cyclin D1 antisense oligodeoxynucleotides exert different efficacy on the inhibition of cell growth and gene expression. We suggest that selection and characterization of high affinity oligodeoxynucleotides is strictly required before the application of antisense technology.

Base Sequence↗
PubMed1998

Hypoxia exerts cell-type-specific effects on expression of the class 3 aldehyde dehydrogenase gene.

The Class 3 aldehyde dehydrogenase gene (ALDH3) is expressed differentially in a tissue-specific manner, occurring constitutively in some tissues and in others as a result of xenobiotic induction via the Ah receptor/ARNT pathway. ARNT is also involved in regulating gene expression in response to hypoxia. It dimerizes with hypoxia-inducible factor 1 alpha (HIF-1 alpha) and enhances expression of hypoxia-responsive genes. To determine if ARNT plays a role in regulating ALDH3 in response to low oxygen tension, we studied the effects of 1% oxygen and the hypoxia mimic cobalt chloride on constitutive and inducible ALDH3 expression in rat hepatoma cells and rat corneal epithelial cells. Hypoxia sharply down-regulates constitutive ALDH3 expression in corneal epithelial cells. Likewise, aromatic hydrocarbon-induced ALDH3 expression in H4-II-EC3 cells is significantly reduced by hypoxia. In contrast, hypoxia has no effect on constitutive or aromatic hydrocarbon-inducible ALDH3 expression in HTC cells. Our data indicate that hypoxia exerts cell type-specific effects on both constitutive and induced ALDH3 expression.

Aldehyde Dehydrogenase↗
PubMed2000

C60 carboxyfullerene exerts a protective activity against oxidative stress-induced apoptosis in human peripheral blood mononuclear cells.

C60 carboxyfullerene is a novel buckminsterfullerene-derived compound that behaves as a free-radical scavenger. In the present report, we investigated whether this drug exerts a protective activity against oxidative stress-induced apoptosis. Human peripheral blood mononuclear cells (PBMCs) were challenged by 2-deoxy-d-ribose (dRib) or TNF-alpha plus cycloheximide as agents that trigger apoptosis by interfering with the redox status of cell and mitochondrial membrane potential. We found that carboxyfullerene was able to protect quiescent PBMCs from apoptosis caused either by 2-deoxy-d-ribose or TNF-alpha plus cycloheximide by a mechanism partially involving the mitochondrial membrane potential integrity, known to be associated with early stages of apoptosis. These results represent the first indication for a target activity of buckminsterfullerenes on cells of the immune system and their mitochondria.

Adult↗
PubMed1997

The p53-regulated cyclin G gene promotes cell growth: p53 downstream effectors cyclin G and Gadd45 exert different effects on cisplatin chemosensitivity.

Among the p53-regulated genes that have been identified thus far, cyclin G is a relatively recent one. We conducted a series of experiments aimed at elucidating cyclin G function. Ectopic overexpression of cyclin G in human RKO colon carcinoma cells accelerated cell growth. Transfection of normal human fibroblasts with the cyclin G expression vector promoted clonal expansion. Cyclin G immune complexes isolated from the transfected cells exhibited appreciable levels of cyclin-dependent kinase activity, as evidenced using histone H1 as a substrate. The retinoblastoma protein, pRb, was detectable in cyclin G immune complexes, raising the possibility that Rb may be one mediator of cyclin G action. Cyclin G-overexpressing cells were more sensitive to cisplatin cytotoxicity than the parent cells, probably because cyclin G overexpression overrides cell cycle checkpoint(s). Overexpression of another p53-regulated gene, GADD45, by contrast, protected cells from cisplatin killing. These findings suggest that different downstream effectors of the p53 pathway may exert different effects on cellular survival after treatment with cancer chemotherapy drugs such as cisplatin.

Antineoplastic Agents↗
PubMed2001

Latanoprost exerts neuroprotective activity in vitro and in vivo.

Prostaglandins may influence cyclo-oxygenase (COX-2) and nitric oxide (NO) synthase activity, thus interfering with ischemia-induced neurotoxic processes. The prostaglandin synthetic derivative, latanoprost was tested in different in vivo and in vitro models of neuronal damage in order to study its influence on these processes. Ischemia was induced in rats by bilateral occlusion of the carotid arteries for 30 min. Latanoprost (0.01 mg x kg(-1)per die, i.p. for 3 days) or the ionotropic glutamate receptors antagonist, MK-801 (0.1 mg x kg(-1)per die, i.p. for 3 days) were equal in preventing lactate accumulation in retinal tissue of animals subjected to acute ischemia. Similar results were obtained in animals with retinal ischemia induced by increasing intraocular pressure to 120 mm Hg for 45 min. PGF2alpha, PGE2, latanoprost and acid of latanoprost (PhXA85) reduced the release of LDH from primary cultures of human retinal cells in vitro subjected to glutamate (10 microM) or hypoxia/re-oxygenation exposure. This effect was observed only at concentrations of 1-0.01 microM for PGF2alpha and PGE2, and of 0.1-0.001 microM for latanoprost (0.01 microM-0.1 nM for PhXA85). The COX-2 activity in cultured retinal cells exposed to glutamate was measured as PGE2 production when latanoprost was applied compared to arachidonic acid (AA) at different molar concentrations. The COX-2 activity was reduced by arachidonic acid (0.1-0.01 microM) as well as by latanoprost (0.1-0.001 microM) and PhXA85 (0.01-0.001 microM) in retinal cells exposed to glutamate. Inhibition of inducible NO synthase was also found with the same drug concentrations. These results suggest that latanoprost exerts a neuroprotective activity in vitro and in vivo. This effect seems to be present only at low concentrations of the drug. A negative feedback on neuronal COX-2 activity may be possibly involved.

Analysis of Variance↗
PubMed1993

Noncompetitive and competitive NMDA antagonists exert anticonvulsant effects by actions on different sites within the neuronal network for audiogenic seizures.

Excitant amino acids are implicated in audiogenic seizure (AGS) susceptibility in the genetically epilepsy-prone rat (GEPR). In the present study systemic administration of NMDA receptor antagonists significantly decreased AGS severity in the GEPR. Systemic administration of the competitive NMDA antagonists 3-((+-)-2-carboxypiperazin-4-yl)-propyl-1-phosphonate (CPP) and 2-amino-7-phosphonoheptanoic acid and the non-competitive antagonist dizocilpine (MK-801) were effectively anticonvulsant in the GEPR. The inferior colliculus is the most critical nucleus for AGS initiation in the GEPR and an excitant amino acid is implicated as an important excitatory transmitter in inferior colliculus neurons. Systemically administered CPP significantly reduced inferior colliculus neuronal firing in the normal behaving rat and the GEPR concurrently with blockade of AGS and this effect occurred at nearly all sound intensities tested. Systemic administration of MK-801, while effective in blocking AGS, produced no consistent change in inferior colliculus neuronal firing, which is consistent with its very low potency in blocking AGS with bilateral microinjection into the inferior colliculus. These findings suggest that an important action of competitive, but not noncompetitive, NMDA antagonists is on brain stem auditory nuclei, especially the inferior colliculus, that are critical to AGS. MK-801 appears to exert its anticonvulsant effects in AGS network sites beyond the inferior colliculus. These findings and recent inferior colliculus slice studies suggest that NMDA receptors in inferior colliculus may have quantitatively different properties from those in other brain regions. These differences in NMDA receptor function in inferior colliculus may reflect NMDA receptor heterogeneity observed in binding studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗
PubMed2001

Attraction exerted in vivo by grafts of embryonic neocortex on developing thalamic axons.

In a previous study we provided evidence that embryonic (E) day 16 frontal cortical cells grafted into the occipital cortex of newborn rats receive inputs from the ventrolateral (VL) and ventromedial (VM) thalamic nuclei which, normally, project to the frontal cortex (25). The present study was designed to examine further the conditions of development of the thalamic innervation of heterotopic neocortical grafts. We demonstrate that VL/VM axons do not provide transitory aberrant input to the occipital cortex either in intact newborn animals or in rats having received neonatal occipital lesion and subsequent graft of E16 occipital cells. These findings indicate, therefore, that the VL/VM projection to the graft does not result from the stabilization of an initial widespread cortical projection from these thalamic nuclei occurring either spontaneously or in response to the lesion and homotopic transplantation procedures. We also show that the VL/VM projection to frontal-to-occipital grafts develops within a few days posttransplantation and is maintained in adulthood. Finally, this study establishes that most VL/VM axons which enter the grafts are not collaterals of thalamofrontal axons. After having reached the cortex, they proceed caudally primarily within the infragranular layers. The findings of this and previous (25) in vivo studies for the first time provide evidence that developing thalamic axons have the capacity to respond to signals from grafts of E16 cortical cells and are capable of deviating their trajectory to establish contact with the grafts. Only those axons arising from thalamic nuclei appropriate for the cortical locus of origin of the grafted cells respond to the guidance signals. The mechanisms by which the thalamic axons find their way to the graft probably rely on cell-contact signaling and/or long-range attraction exerted by diffusible molecules.

Animals↗
PubMed1998

Peripheral nerve grafts exert trophic and tropic effects on anterior thalamic neurons.

Peripheral nerve grafting into the central nervous system (CNS) has been used to study the regenerative capabilities of central neurons given access to a peripheral nervous system (PNS) environment. It is well documented that many CNS neurons regenerate axons along peripheral nerve grafts placed in close proximity to their cell bodies and that these grafts can ameliorate axotomy-induced retrograde degeneration. In the present study, we placed peripheral nerve grafts in proximity to axotomized neurons of the anterior thalamus. Standard histological and retrograde tracing techniques were used to examine these preparations 2 months after grafting. Three effects of these grafts were observed: amelioration of retrograde degeneration of axotomized anterior thalamic neurons, hypertrophy of many thalamic neurons in the local environment of the graft, and ingrowth of axons of axotomized anterior thalamic neurons as well as nonaxotomized neurons from surrounding nuclei. We conclude from these studies that peripheral nerve grafts not only provide a matrix for axonal outgrowth but also exert marked trophic and tropic effects on axotomized anterior thalamic neurons.

Animals↗
PubMed2001

1,5-Benzodiazepine tricyclic derivatives exerting anti-inflammatory effects in mice by inhibiting interleukin-6 and prostaglandinE(2)production.

The 1,4- and the 1,5-benzodiazepines (BDZ) are commonly used as anxiolytic and anticonvulsive drugs. It has been suggested that they influence, particularly through stimulation of peripheral BDZ receptors, some immune cell properties such as pro-inflammatory cytokine production. The availability of a new class of [1,2,4]triazolo[4,3-a][1,5]benzodiazepine derivatives (compounds IV), endowed with anti-inflammatory and/or analgesic properties but no anti-pentylenetetrazole activity, prompted us to investigate in more detail the anti-inflammatory properties of three selected compounds IV (N,N-dimethyl-1-phenyl-4H-[1,2,4]triazolo[4,3-a][1,5]benz- odiazepin-5-amine; N,N-dibutyl-4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepin-5-amine; 1-methyl-N,N-dimethyl-4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepin-5-amine) and one structurally related compound (1-phenyl-4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepin-5(6H)-one). These BDZ derivatives have lost their affinity for the central and peripheral BDZ receptors. The in vivo effect on leukocyte migration of these compounds was investigated by using the mouse air-pouch model of local inflammation. Compounds A and B, significantly inhibited the carrageenan-induced leukocyte recruitment in a dose-dependent manner starting from the dose of 50 mgkg(-1), whereas compound C was effective only at the higher dose of 100 mgkg(-1). Compound D did not exert such effects at any of the doses considered. The effect of compounds A, B and C on leukocyte recruitment was paralleled by a significant inhibition of interleukin-6 and prostaglandin E(2)production in the exudate, similarly to indomethacin, and by a partial reduction of vascular permeability. These features may be relevant for the design and development of innovative anti-inflammatory molecules among the 4H-[1,2,4]triazolo[4,3-a][1,5]benzodiazepin-5-amine derivatives.

Analgesics↗
PubMed2003

Low molecular weight compounds with affinity to melanocortin receptors exert neuroprotection in spinal cord injury--an experimental study in the rat.

The possibility that five new low molecular weight compounds with varying affinity and selectivity to the melanocortin receptors will exert neuroprotective effects in the spinal cord injury (SCI) induced edema formation and cell damage was examined in a rat model. A focal trauma of the rat spinal cord made by an incision into the right dorsal horn (T10-11) resulted in profound edema formation, leakage of Evans blue albumin and cell injury of the T9 segment at 5 h. Topical application of the Melacure compound ME10501 in high doses (10 microg in 10 microl) given 5 min after SCI resulted in most significant neuroprotection of the T9 segment of the cord compared to other compounds. Thus, marked reduction in water content, leakage of Evans blue albumin, and cell injury were observed in ME10501 treated traumatised rats. These observations suggest that the non-peptide compound ME10501 with affinity to the melanocortin receptor MC4 is capable to induce neuroprotection in the spinal cord following trauma not reported earlier.

Animals↗
PubMed1992

Antianginal effects of amlodipine at a single dose on exertional angina patients using treadmill exercise testing--a randomized crossover study in comparison with placebo.

With eight cases of stable exertional angina as subjects, the antianginal action and sustained effects of single 10 mg oral doses of new calcium antagonists amlodipine were assessed by treadmill exercise tests in randomized crossover trials with respect to a placebo. Exercise tests were conducted before as well as 4, 8, and 24 hours after administration, and plasma amlodipine concentration was investigated at the same times. The maximal exercise time was 299 +/- 43 seconds before as compared with 346 +/- 49 seconds 4 hours after administration and 368 +/- 50 seconds 8 hours after administration, a significant prolongation in each case (p < 0.01). Moreover, the exercise time elapsed until 1 mm of ST-segment depression, as well as the ST-segment depression measured at the same time, were both significantly improved as compared with the placebo results. The plasma amlodipine concentration reached a peak 8 hours after administration and displayed an effective level even 24 hours after administration. The value of delta PRP measured at the same time during the exercise test was also significantly reduced as compared with the placebo results, even 24 hours after administration of amlodipine. These findings supported the conclusion that single 10-mg doses of amlodipine provide stable antianginal action over a 24-hour period.

Administration, Oral↗
PubMed1994

Daudi supernatant, unlike other H-Y antigen sources, exerts a sex-reversing effect on embryonic chick gonad differentiation.

In vitro cultures of intact chick gonads (organ cultures) and reaggregation cultures of dispersed gonad cells (roller cultures) were made. Gonads or gonad cells from 7-day-old chick embryos, at the stage when sex-specific differentiation begins, were cultured in the presence of presumed H-Y antigen-containing supernatants, or co-cultured in the presence of H-Y antigen-producing cell lines. The H-Y antigen-producing cells tested were of human, mouse, bovine and chicken origin. During organ culture, addition of supernatant of the human lymphoma cell line Daudi, or co-culture with Daudi cells, stimulated a clear proliferation of the germinal epithelium in male gonads, indicating feminization. A similar effect was obtained by treatment with estradiol. In reaggregation culture, the increase in nuclear size of germ cells was chosen as a parameter for feminization. A significant increase of germ cell nuclear size was observed in gonads cultured in the presence of Daudi supernatant. In both organ cultures and reaggregation cultures, other tested H-Y antigen sources and semi-purified H-Y antigen fractions did not exert significant effects on differentiation of the gonads or on the average area of the germ cell nuclei. These findings suggest that it is not H-Y antigen, but another protein produced by Daudi cells, that might be responsible for the sex-reversing effects.

Animals↗
PubMed1989

Single medullary reticulospinal neurons exert postsynaptic inhibitory effects via inhibitory interneurons upon alpha-motoneurons innervating cat hindlimb muscles.

This study was aimed at elucidating the brainstem-spinal mechanisms of postural suppression evoked by stimulating the dorsal portion of the caudal tegmental field (DTF) in the pons. For this purpose, we first sampled a group of reticulospinal neurons located in the medial part of medullary reticular formation, which were activated orthodromically and antidromically by stimulating the DTF area and the first lumbar spinal segment, respectively (DTF-RS neurons; N = 26). These DTF-RS neurons were located within the nucleus reticularis gigantocellularis (NRGc) and projected their descending axons to the lumbar spinal cord through the ventrolateral funiculus. The postsynaptic inhibitory effects of single DTF-RS neurons upon hindlimb alpha-MNs intracellularly recorded (N = 78) were then studied with spike-triggered averaging. Twelve DTF-RS neurons evoked IPSPs in 21 hindlimb alpha-MNs. Five DTF-RS neurons exerted postsynaptic inhibitory effects upon more than one alpha-MNs. These alpha-MNs were located from L5 to S1 segments of the spinal cord. A mean latency of IPSPs which was measured from the onset of the trigger spike was 5.1 ms with time to peak of 1.8 ms, and the mean segmental delay of the IPSPs was 1.5 ms, which was measured from the onset of the descending axonal volley recorded extracellularly adjacent to alpha-MNs. Amplitudes of the IPSPs were augmented with an increase in the firing frequencies of the DTF-RS neurons, the increase being produced by iontophoretic application of glutamate. These characteristics of the IPSPs suggest that reticular effects are mediated at least by a single spinal inhibitory interneuron. These results suggest that the DTF-NRGc system participates in generalized motor inhibition.

Action Potentials↗
PubMed1987

The 20 bp, directly repeated DNA sequence of broad host range plasmid R1162 exerts incompatibility in vivo and inhibits R1162 DNA replication in vitro.

The broad host range plasmid R1162 contains a directly repeated, 20 bp DNA sequence in the region of the plasmid required in cis for replication and maintenance. This sequence has been chemically synthesized and cloned, and shown to be sufficient for expression of plasmid incompatibility. The sequence also inhibits replication of R1162 DNA in a cell-free system. The strengths of both these effects are determined by the number of direct repeats (DRs) present, and are also affected to similar degrees by different mutations within the repeated sequence. Several of the mutations were tested for their effect in cis on plasmid maintenance in the cell, and one was found to cause an increase in plasmid copy number. The results suggest that the direct repeats exert incompatibility by inhibiting DNA replication, presumably because they are the binding sites for a limiting essential protein.

Base Composition↗
PubMed1984

Amber dnaG mutation exerting a polar effect on the synthesis of RNA polymerase sigma factor in Escherichia coli.

Three amber mutants of Escherichia coli, dnaG9, dnaG24 and dnaG26, affected in the structural gene (dnaG) for "primase" have been isolated from a parental strain carrying a temperature-sensitive amber suppressor (supF-Ts6). These mutants grow at 30 degrees C but not at 42 degrees C since primase is essential for growth and is synthesized only at low temperatures. Chimeric plasmids carrying dnaG+ but no other chromosomal genes of E. coli complemented the amber mutations, and the plasmid carrying a part of dnaG lost the complementing activity. Beside, plasmids carrying a dnaG amber mutation complemented a temperature-sensitive dnaG mutation only in the presence of amber suppressor. One of the amber mutations, dnaG24 which maps proximal to the NH2-terminus of the dnaG gene, exerted a polar effect on the synthesis of RNA polymerase sigma factor in E. coli.

DNA Primase↗
PubMed1993

Extracellular calcium exerts a dual effect on renin secretion from isolated mouse juxtaglomerular cells.

Utilizing primary cultures of mouse renal juxtaglomerular cells we found that renin secretion during 20 h of incubation was stimulated by 100% when extracellular calcium was lowered from a basal level of 0.5 mM to below 1 microM, and was enhanced in a concentration-dependent fashion by 600% when extracellular calcium was increased up to 10 mM. The stimulatory effect of low calcium on renin secretion was apparent after the first hour of incubation, whereas the stimulatory effect of increased calcium occurred with a delay of at least 1 h. During the first hour of incubation increased extracellular calcium blunted the stimulation of renin secretion induced by forskolin (10 microM). The stimulatory effect of increased calcium was attenuated in the presence of 8-pCPT-cGMP, a membrane-permeable cGMP analogue, and in the presence of 100 mM sucrose. The stimulatory effect of increased calcium was blunted in the presence of 0.5 mM cobalt, which itself stimulated renin secretion at normal (0.5 mM) calcium concentrations. Renin synthesis by the cultured cells at low calcium was markedly attenuated in proportion with total protein synthesis, whereas renin synthesis was not altered at increased calcium concentrations. Our findings suggest that a rise of intracellular calcium, induced by an increase of extracellular calcium, is associated with a transient inhibition followed by a marked and regulatable stimulation of renin secretion. Neither calcium depletion nor calcium elevation appears to exert specific effects on renin synthesis in juxtaglomerular cells.

Animals↗
PubMed1981

On the forces exerted on the hip during gait.

Starting from the data of Braune and Fischer on the human gait and of Fick on the hip muscles, the forces acting on the hip joint during gait are calculated in tridimensional space. The analysis confirms the study on the same subject by Pauwels with a simpler method, as far as the coronal projection is concerned. In the horizontal plane, the resultant force exerted on the hip seems to be greater and its direction is different from that described by Pauwels.

Biomechanical Phenomena↗