Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 31
Filter
1.
BMC Neurol ; 16: 77, 2016 May 23.
Article in English | MEDLINE | ID: mdl-27215274

ABSTRACT

BACKGROUND: Andrographis paniculata (A. paniculata), a medicinal plant, has shown anti-inflammatory, neuroprotective and antifibrotic effects in animal models as well as clinical efficacy in different studies, including an anti-fatigue effect in autoimmune diseases such as rheumatoid arthritis. In multiple sclerosis (MS), fatigue is rated as one of the most common and disabling symptoms. In the present trial, we investigated the effect of A. paniculata on relapse rate and fatigue in relapsing-remitting MS (RRMS) patients receiving interferon beta. METHODS: A randomised double-blind placebo-controlled trial assessed the effects of 170 mg of A. paniculata dried extract tablet b.i.d. p.o. on relapse rate and fatigue using the Fatigue Severity Scores (FSS) over 12 months in RRMS patients receiving interferon. The Expanded Disability Status Scale (EDSS) score, inflammatory parameters and radiological findings were also investigated. Twenty-five patients were enrolled, and twenty-two patients were ultimately analysed and randomised to the active or placebo group. RESULTS: Patients treated with A. paniculata showed a significant reduction in their FSS score as compared to the placebo, equivalent to a 44 % reduction at 12 months. No statistically significant differences were observed for relapse rate, EDSS or inflammatory parameters, with a trend in reducing new lesions among the A. paniculata group. One patient in the A. paniculata group presented with a mild and transient skin rash, which was alleviated with anti-histamine treatment for three weeks. CONCLUSION: A. paniculata was well tolerated in patients and no changes in clinical parameters were observed. A. paniculata significantly reduces fatigue in patients with RRMS receiving interferon beta in comparison to placebo and only interferon beta treatment. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02280876 ; Trial registration date: 20.10.2014.


Subject(s)
Andrographis , Fatigue/drug therapy , Multiple Sclerosis, Relapsing-Remitting/complications , Multiple Sclerosis, Relapsing-Remitting/drug therapy , Phytotherapy , Plant Extracts/therapeutic use , Adolescent , Adult , Animals , Double-Blind Method , Fatigue/etiology , Female , Humans , Interferon-beta/therapeutic use , Male , Middle Aged , Pilot Projects , Young Adult
2.
Transl Psychiatry ; 1: e20, 2011 Jul 12.
Article in English | MEDLINE | ID: mdl-22832522

ABSTRACT

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by a progressive deterioration of cognitive abilities, amyloid-ß peptide (Aß) accumulation and synaptic alterations. Previous studies indicated that hyperforin, a component of the St John's Wort, prevents Aß neurotoxicity and some behavioral impairments in a rat model of AD. In this study we examined the ability of tetrahydrohyperforin (IDN5607), a stable hyperforin derivative, to prevent the cognitive deficit and synaptic impairment in an in vivo model of AD. In double transgenic APPswe/PSEN1ΔE9 mice, IDN5706 improves memory and prevents the impairment of synaptic plasticity in a dose-dependent manner, inducing a recovery of long-term potentiation. In agreement with these findings, IDN5706 prevented the decrease in synaptic proteins in hippocampus and cortex. In addition, decreased levels of tau hyperphosphorylation, astrogliosis, and total fibrillar and oligomeric forms of Aß were determined in double transgenic mice treated with IDN5706. In cultured cells, IDN5706 decreased the proteolytic processing of the amyloid precursor protein that leads to Aß peptide generation. These findings indicate that IDN5706 ameliorates AD neuropathology and could be considered of therapeutic relevance in AD treatment.


Subject(s)
Alzheimer Disease/drug therapy , Amyloid beta-Peptides/metabolism , Amyloid beta-Protein Precursor/metabolism , Phloroglucinol/analogs & derivatives , Presenilin-1/genetics , Protein Processing, Post-Translational , Synaptic Transmission/genetics , Terpenes/pharmacology , tau Proteins/metabolism , Alzheimer Disease/genetics , Alzheimer Disease/prevention & control , Amyloid beta-Peptides/antagonists & inhibitors , Amyloid beta-Peptides/genetics , Amyloid beta-Protein Precursor/antagonists & inhibitors , Amyloid beta-Protein Precursor/genetics , Animals , Disease Models, Animal , Mice , Mice, Transgenic , Phloroglucinol/administration & dosage , Phloroglucinol/pharmacology , Protein Processing, Post-Translational/genetics , Synaptic Transmission/drug effects , Terpenes/administration & dosage
3.
Curr Alzheimer Res ; 7(2): 126-33, 2010 Mar.
Article in English | MEDLINE | ID: mdl-19939230

ABSTRACT

The use of natural compounds is an interesting stratagem in the search of drugs with therapeutic potential for the treatment of Alzheimer's disease (AD). We report here the effect of the hyperforin derivative (IDN5706, tetrahydrohyperforin), a semi-synthetic derivative of the St. John's Wort, on the brain neuropathology, learning and memory in a double transgenic (APPswe, PS-1dE9) mouse model of AD. Results indicate that, IDN5706 alleviates memory decline induced by amyloid-beta (Abeta) deposits as indicated by the Morris water maze paradigm. Moreover, the analysis of Abeta deposits by immunodetection and thioflavin-S staining of brain sections, only reveals a decrease in the frequency of the larger-size Abeta deposits, suggesting that IDN5706 affected the turnover of amyloid plaques. Immunohistochemical analysis, using GFAP and n-Tyrosine indicated that the hyperforin derivative prevents the inflammatory astrocytic reaction and the oxidative damage triggered by high Abeta deposit levels. We conclude that the hyperforin derivative, IDN5706, has therapeutic potential for prevention and treatment of AD.


Subject(s)
Alzheimer Disease/drug therapy , Brain/drug effects , Memory Disorders/drug therapy , Phloroglucinol/analogs & derivatives , Terpenes/pharmacology , Alzheimer Disease/metabolism , Alzheimer Disease/physiopathology , Amyloid beta-Peptides/drug effects , Amyloid beta-Peptides/metabolism , Animals , Astrocytes/drug effects , Astrocytes/pathology , Brain/metabolism , Brain/physiopathology , Bridged Bicyclo Compounds/pharmacology , Bridged Bicyclo Compounds/therapeutic use , Disease Models, Animal , Encephalitis/drug therapy , Encephalitis/physiopathology , Encephalitis/prevention & control , Glial Fibrillary Acidic Protein/analysis , Glial Fibrillary Acidic Protein/metabolism , Gliosis/drug therapy , Gliosis/physiopathology , Gliosis/prevention & control , Humans , Maze Learning/drug effects , Maze Learning/physiology , Memory Disorders/metabolism , Memory Disorders/physiopathology , Mice , Mice, Transgenic , Oxidative Stress/drug effects , Oxidative Stress/physiology , Phloroglucinol/pharmacology , Phloroglucinol/therapeutic use , Terpenes/therapeutic use , Tyrosine/analysis , Tyrosine/metabolism
4.
Clin Rheumatol ; 28(8): 931-46, 2009 Aug.
Article in English | MEDLINE | ID: mdl-19408036

ABSTRACT

Andrographis paniculata (Burm. f.) Wall ex Nees (Acanthaceae) possesses anti-inflammatory effects, attributed to the main constituent andrographolide proposed as alternative in the treatment of autoimmune disease. A prospective, randomized, double blind, and placebo-controlled study in patients with rheumatoid arthritis (RA) was performed. Tablets (Paractin) made of an extract of A. paniculata (30% total andrographolides) were administered three times a day for 14 weeks, after a 2-week washout period to 60 patients with active RA. The primary outcomes were pain intensity measured using a horizontal visual analog pain scale (VAPS). In addition, ACR, EULAR, and SF36 clinical parameters were recorded. The intensity of joint pain decreased in the active vs placebo group at the end of treatment, although these differences were not statistically significant. A significant diminishing for week in tender joint -0.13 95% confidence interval (CI; -0.22 to 0.06; p = 0.001), number of swollen joints -0.15 95%CI (-0.29 to -0.02; p = 0.02), total grade of swollen joint -0.27 95%CI (-0.48 to -0.07; p = 0.010), number of tender joints -0.25 95%CI (-0.48 to -0.02; p = 0.033), total grade of swollen joints -0.27 95%CI (-0.48 to -0.07; p = 0.01), total grade of tender joints -0.47 95%CI (-0.77 to -0.17; p = 0.002) and HAQ -0.52 95%CI (-0.82 to -0.21; p < 0.001) and SF36 0.02 95%CI (0.01 to 0.02; p < 0.001) health questionnaires was observed within the group with the active drug. Moreover, it was associated to a reduction of rheumatoid factor, IgA, and C4. These findings suggest that A. paniculata could be a useful "natural complement" in the treatment of AR; however, a larger trial and a more extended period of treatment is necessary in order to corroborate these results.


Subject(s)
Andrographis , Arthralgia/drug therapy , Arthritis, Rheumatoid/drug therapy , Phytotherapy , Plant Extracts/therapeutic use , Adolescent , Adult , Aged , Arsenicals , Arthritis, Rheumatoid/blood , Arthritis, Rheumatoid/diagnostic imaging , Chloroquine/therapeutic use , Double-Blind Method , Drug Therapy, Combination , Female , Glutathione/analogs & derivatives , Humans , Methotrexate/therapeutic use , Middle Aged , Placebos , Plant Leaves , Prednisone/therapeutic use , Prospective Studies , Radiography , Severity of Illness Index , Young Adult
5.
Mini Rev Med Chem ; 9(2): 153-68, 2009 Feb.
Article in English | MEDLINE | ID: mdl-19200021

ABSTRACT

The importance of neutrophils in human disease such as rheumatoid arthritis, asthma, adult respiratory distress syndrome, and COPD has prompted the search for drugs capable to slow down neutrophil-dependent inflammation, without interference with innate immune responses. In this review, we summarize new potential drugs targets against neutrophils mediated inflammatory responses.


Subject(s)
Anti-Inflammatory Agents/pharmacology , Inflammation/drug therapy , Inflammation/pathology , Neutrophils/drug effects , Neutrophils/pathology , Animals , Humans , Immunity, Innate/drug effects
6.
Vet Immunol Immunopathol ; 115(3-4): 286-98, 2007 Feb 15.
Article in English | MEDLINE | ID: mdl-17157922

ABSTRACT

Propionate is a short-chain fatty acid produced under normal physiological conditions in the rumen of cattle. It is also involved in the inflammatory process and neutrophil function via calcium release, reactive oxygen species and intracellular pH (pH(i)) changes. This study examined the effect of propionate on the pH(i) of bovine neutrophils; specifically if pH(i) changes are controlled by calcium flux, and the mitogen-activated protein kinase (MAPK) pathway. Propionate caused rapid intracellular acidification and sustained alkalinization in bovine neutrophils loaded with 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein acetoxymethyl ester (BCECF-AM), a fluorescent indicator of pH(i). The acidification phase seems to be controlled by intracellular calcium release and p38 MAPK pathway. The pH recovery phenomenon was mediated by an amiloride-sensitive Na+/H+ exchanger and H+ channel, and was inhibited by UO126 (an ERK1/2 MAPK phosphorylation inhibitor), Gö6850 (a PKC inhibitor) and calcium chelating. Ionomycin, a calcium ionophore, induced intracellular acidification and sustained alkalinization. The intracellular acidification was strongly inhibited by BAPTA-AM (an intracellular calcium chelator) and SB203580 (a p38 MAPK inhibitor). In addition, the intracellular alkalinization was reduced by EGTA (a calcium chelator), UO126, LY294002 (a PI3K inhibitor) and Gö6850. Propionate did not increase superoxide production, however it reduced the superoxide production induced by platelet-activating factor (PAF), and increased the release of superoxide induced by ionomycin. Our results suggest that propionate-induced intracellular acidification is mediated by intracellular calcium release and p38 MAPK activation, and that pH recovery is controlled via ERK1/2 MAPK, PKC and calcium entry in bovine neutrophils.


Subject(s)
Calcium/blood , Cattle/blood , Extracellular Signal-Regulated MAP Kinases/blood , Neutrophils/drug effects , Neutrophils/metabolism , Propionates/pharmacology , Protein Kinase C/blood , Animals , Butadienes/pharmacology , Chelating Agents/pharmacology , Chromones/pharmacology , Egtazic Acid/analogs & derivatives , Egtazic Acid/pharmacology , Extracellular Signal-Regulated MAP Kinases/antagonists & inhibitors , Female , Hydrogen-Ion Concentration , Imidazoles/pharmacology , Indoles/pharmacology , Ionomycin/pharmacology , Maleimides/pharmacology , Morpholines/pharmacology , Neutrophils/enzymology , Nitriles/pharmacology , Protein Kinase C/antagonists & inhibitors , Protein Kinase Inhibitors/pharmacology , Pyridines/pharmacology , Sodium-Hydrogen Exchangers/metabolism , Spectrometry, Fluorescence/veterinary , p38 Mitogen-Activated Protein Kinases/antagonists & inhibitors , p38 Mitogen-Activated Protein Kinases/blood
7.
Mol Psychiatry ; 11(11): 1032-48, 2006 Nov.
Article in English | MEDLINE | ID: mdl-16880827

ABSTRACT

The major protein constituent of amyloid deposits in Alzheimer's disease (AD) is the amyloid beta-peptide (Abeta). In the present work, we have determined the effect of hyperforin an acylphloroglucinol compound isolated from Hypericum perforatum (St John's Wort), on Abeta-induced spatial memory impairments and on Abeta neurotoxicity. We report here that hyperforin: (1) decreases amyloid deposit formation in rats injected with amyloid fibrils in the hippocampus; (2) decreases the neuropathological changes and behavioral impairments in a rat model of amyloidosis; (3) prevents Abeta-induced neurotoxicity in hippocampal neurons both from amyloid fibrils and Abeta oligomers, avoiding the increase in reactive oxidative species associated with amyloid toxicity. Both effects could be explained by the capacity of hyperforin to disaggregate amyloid deposits in a dose and time-dependent manner and to decrease Abeta aggregation and amyloid formation. Altogether these evidences suggest that hyperforin may be useful to decrease amyloid burden and toxicity in AD patients, and may be a putative therapeutic agent to fight the disease.


Subject(s)
Alzheimer Disease/drug therapy , Amyloid beta-Peptides/drug effects , Hypericum , Phloroglucinol/analogs & derivatives , Plant Extracts/pharmacology , Terpenes/pharmacology , Alzheimer Disease/metabolism , Amyloid beta-Peptides/metabolism , Amyloidosis/drug therapy , Amyloidosis/metabolism , Analysis of Variance , Animals , Bridged Bicyclo Compounds/pharmacology , Bridged Bicyclo Compounds/therapeutic use , Disease Models, Animal , Dose-Response Relationship, Drug , Drug Administration Schedule , Escape Reaction/drug effects , Hippocampus/drug effects , Hippocampus/metabolism , Male , Maze Learning/drug effects , Microinjections , Neuroprotective Agents/administration & dosage , Neuroprotective Agents/therapeutic use , Phloroglucinol/pharmacology , Phloroglucinol/therapeutic use , Phytotherapy , Plant Extracts/therapeutic use , Rats , Rats, Sprague-Dawley , Reactive Oxygen Species/metabolism , Terpenes/therapeutic use , Time Factors
8.
Phytother Res ; 15(3): 235-9, 2001 May.
Article in English | MEDLINE | ID: mdl-11351359

ABSTRACT

The possible relaxation of uterine smooth muscle by Andrographis paniculata dried extract via a blockade of voltage operated calcium channels was investigated in rats. Uterine horns pretreated with oestradiol were incubated in Ca(+2) -free Jalon's solution and stimulated with KCl (20-60 mM) in order to produce depolarization of the membrane. The isometric contractile response to 1 mM or cumulative concentrations of CaCl2 were blockaded by 0.2, 0.4 and 0.8 mg/mL of A. paniculata. The maximum contractile response induced by acetylcholine was moderately antagonized by A. paniculata. The possible blockade of Ca(+2) entry by A. paniculata was evaluated with (45)Ca(+2) uptake in uterine rings incubated with free-Ca(+2)-Ringer's solution high in K+ (KCl 40 mM). The influx was completely blockaded with 0.4 mg/mL of A. paniculata. These results strongly suggest that A. paniculata blockades voltage operated calcium channels inhibiting the entry of Ca(+2) from the external medium.


Subject(s)
Calcium Channel Blockers/pharmacology , Drugs, Chinese Herbal/pharmacology , Muscle Relaxation/drug effects , Plants, Medicinal , Uterine Contraction/drug effects , Animals , Female , Rats , Rats, Sprague-Dawley
9.
J Ethnopharmacol ; 71(1-2): 115-21, 2000 Jul.
Article in English | MEDLINE | ID: mdl-10904154

ABSTRACT

The possible blockade of voltage-operated calcium channels (VOCs) by Andrographis paniculata dried extract in vas deferens smooth muscle was investigated in rats. The tissues were incubated in Ca(2+)-free Kreb's solution and stimulated with KCl (40 mM) to produce depolarisation of the membrane. The isometric contractile response to cumulative concentrations of CaCl(2) was effectively blockaded by 0.2 and 0.4 mg/ml A. paniculata. In other experiments, the maximum contractile response induced by norepinephrine was not antagonised by 0.2, 0.4 or 0.8 mg/ml A. paniculata. The possible blockade of Ca(2+) entry by A. paniculata was evaluated with 45Ca(2+) uptake in vas deferens treated with reserpine (5 and 2.5 mg/kg) 48 and 24 h before the experiments. Epididymal segments were incubated with Ca(2+)-free Kreb's solution with KCl, 25 and 50 mM. The influx was completely blockaded with 0.4 mg/ml A. paniculata. These results suggest that A. paniculata selectively blockades VOCs, hence inhibiting the 45Ca(2+) influx.


Subject(s)
Calcium Channel Blockers/pharmacology , Calcium Channels, P-Type/drug effects , Muscle, Smooth/drug effects , Plants, Medicinal/chemistry , Vas Deferens/drug effects , Animals , Asia , Calcium Channel Blockers/isolation & purification , Calcium Chloride/pharmacology , Calcium Radioisotopes , Chile , In Vitro Techniques , Male , Norepinephrine/pharmacology , Plant Extracts/pharmacology , Rats , Rats, Sprague-Dawley , Vasoconstrictor Agents/pharmacology
10.
Phytomedicine ; 6(4): 217-23, 1999 Oct.
Article in English | MEDLINE | ID: mdl-10589439

ABSTRACT

The objective of our study was to measure the effectiveness of Andrographis paniculata SHA-10 extract in reducing the prevalence and intensity of symptoms and signs of common cold as compared with a placebo. A group of 158 adult patients of both sexes completed the randomized double blind study in Valdivia, Chile. The patients were divided in two equal size groups, one of which received Andrographis paniculata dried extract (1200 mg/day) and the other a placebo during a period of 5 days. Evaluations for efficacy were performed by the patient at day 0, 2, and 4 of the treatment; each completed a self-evaluation (VAS) sheet with the following parameters: headache, tiredness, earache, sleeplessness, sore throat, nasal secretion, phlegm, frequency and intensity of cough. In order to quantify the magnitude of the reduction in the prevalence and intensity of the signs and symptoms of common cold, the risk (Odds Ratio = OR) was calculated using a logistic regression model. At day 2 of treatment a significant decrease in the intensity of the symptoms of tiredness (OR = 1.28; 95% CI 1.07-1.53), sleeplessness (OR = 1.71; 95% CI 1.38-2.11), sore throat (OR = 2.3; 95% CI 1.69-3.14) and nasal secretion (OR = 2.51; 95% CI 1.82-3.46) was observed in the Andrographis SHA-10 group as compared with the placebo group. At day 4, a significant decrease in the intensity of all symptoms was observed for the Andrographis paniculata group. The higher OR values were for the following parameters: sore throat (OR = 3.59; 95% CI 2.04-5.35), nasal secretion (OR = 3.27; 95% CI 2.31-4.62) and earache (OR = 3.11; 95% CI 2.01-4.80) for Andrographis paniculata treatment over placebo, respectively. It is concluded that Andrographis paniculata had a high degree of effectiveness in reducing the prevalence and intensity of the symptoms in uncomplicated common cold beginning at day two of treatment. No adverse effects were observed or reported.


Subject(s)
Antiviral Agents/therapeutic use , Common Cold/drug therapy , Drugs, Chinese Herbal/therapeutic use , Plant Extracts/therapeutic use , Plants, Medicinal , Adult , Antiviral Agents/chemistry , Diterpenes/analysis , Double-Blind Method , Drugs, Chinese Herbal/chemistry , Female , Humans , Logistic Models , Male , Middle Aged , Odds Ratio , Pain Measurement/methods , Plant Extracts/chemistry , Treatment Outcome
11.
J Ethnopharmacol ; 58(3): 219-24, 1997 Nov.
Article in English | MEDLINE | ID: mdl-9421258

ABSTRACT

The possible testicular toxicity of Andrographis paniculata, Nees (Acanthaceae) standardized dried extract was evaluated in male Sprague Dawley rats for 60 days. No testicular toxicity was found with the treatment of 20, 200 and 1000 mg/kg during 60 days as evaluated by reproductive organ weight, testicular histology, ultrastructural analysis of Leydig cells and testosterone levels after 60 days of treatment. It is concluded that Andrographis paniculata dried extract did not produce subchronic testicular toxicity effect in male rats.


Subject(s)
Plants, Medicinal/chemistry , Testicular Diseases/chemically induced , Animals , Leydig Cells/drug effects , Leydig Cells/ultrastructure , Male , Microscopy, Electron , Organ Size/drug effects , Plant Extracts/toxicity , Rats , Rats, Sprague-Dawley , Testicular Diseases/pathology , Testis/pathology , Testis/ultrastructure , Testosterone/blood
12.
Phytomedicine ; 4(2): 101-4, 1997 Jun.
Article in English | MEDLINE | ID: mdl-23195395

ABSTRACT

In a randomized placebo-controlled double blind study, the possible preventive effect against common colds of Kan Jang tablets made from Andrographis paniculata (Barm. F.) (Nees) dried extract was tudied during the winter season. The study was carried in a rural school. The students were divided in two groups, of which Group 1 (n=54), received 2 tablets of Kan Jang per day and Group 2 (n=53), 2 tablets of a placebo (P) per day during three months. The individuals were evaluated weekly by a clinician who diagnosed the presence or absence of common colds during the three months. The analysis of the occurrence of colds revealed that the administration of Kan Jang after the first month did not produced any significant difference. However, after the third month of intake of Kan Jang there was a significant decrease in the incidence of colds as compared to the placebo group. The rate of incidence of colds among the students treated with Kan Jang was 30% (16/54) compared to 62% (33/53). The relative risk of catching a cold was therefore 2.1 (1.32-3.33, 95% confidence interval) times lower for the Kan Jang group. The attributable protective effect of Kan Jang was 33%. The results suggest that Kan Jang tablets have a preventive effect against common colds during the winter period.

13.
Phytomedicine ; 4(2): 145-9, 1997 Jun.
Article in English | MEDLINE | ID: mdl-23195403

ABSTRACT

The possible abortive effect of an extract of Adhatoda vasica leaf spissum, was studied in rats. The principal alkaloid detected in the extract was vasicine (0.85 ± 0.03%). The extract (325 mg/kg/day) was administered with a gastric cannula to a group of 5 pregnant females between day 1 and 9 of pregnancy. In another experiment 9 pregnant females received in the water 0.25 and 2.5% of Adhatoda vasica between day 1 and 9 of pregnancy. It was concluded that the administration of Adhatoda vasica did not produce abortion in any of the treated groups.

14.
Phytomedicine ; 3(3): 237-40, 1996 Nov.
Article in English | MEDLINE | ID: mdl-23195076

ABSTRACT

Sport horses with long lasting high levels of gamma Glutamiltransferase (gGT) and Glutamic Oxalacetic Transaminase (GOT) and Creatinine Phosphokinase (CPK) and poor performance were administered during 14 days 3 g of Caval D'Or®, a standardized dried extract of Schizandra chinensis (fructus) orally. At day "0" the horses were divided into two groups: group 1 received a placebo and group 2 received Caval D'Or®. The results showed that Caval D'Or® is able to reduce significantly the levels of gGT and GOT in the serum at day 7 and 14 after administration. The CPK levels were also reduced by day 7 and 14 after administration of Caval D'Or®. It is concluded that Caval D'Or® facilates the recovery of sport horses in training with poor performance that show high levels of transaminases and CPK.

15.
Mutagenesis ; 9(6): 527-35, 1994 Nov.
Article in English | MEDLINE | ID: mdl-7854144

ABSTRACT

DNA end joining is a major pathway for the elimination of double-strand breaks from chromosomal DNA of higher eucaryotic cells. Extracts of Xenopus laevis eggs rejoin such breaks even when their short single-stranded termini are expected to form imperfectly matched overlaps. However, end-joined products cloned in Escherichia coli, necessarily give rise to perfectly matched products. Therefore it has not been possible to determine whether the end joining process creates mismatched products, perfectly matched (resolved) products or both. To investigate whether mismatch resolution was the result of the X. laevis end joining process or of activities of the bacterial host we used denaturing gradient gel electrophoresis to analyse joined products. We found that the end joining process does include mismatch resolution, the degree of which varies with regard to the nature of the original overlap structure. Mismatches 3' to a gap are completely resolved, mismatches 3' to a nick and 5' to a nick or gap are resolved to some extent but are generally conserved. Mismatches between base matches are always conserved. These findings suggest competing processes of ligation, DNA fill-in synthesis or exonucleolytic excision of mismatched bases next to a gap or nick. At mismatches 3' to a nick the probability of ligation is greater than that of excision while at mismatches 3' to a gap the probability of excision is greater than elongation of a given mismatch. At mismatches 5' to nicks or gaps it appears that ligation or elongation and ligation, respectively, are the most probable pathways but products resulting from mismatch excision, elongation and ligation are also detected.


Subject(s)
DNA, Complementary/chemistry , DNA , Animals , Base Sequence , DNA Probes , Genes, Overlapping , Molecular Sequence Data , Nucleic Acid Heteroduplexes , Plasmids , Sequence Homology, Nucleic Acid , Xenopus laevis/genetics
16.
Mol Cell Biol ; 14(2): 888-95, 1994 Feb.
Article in English | MEDLINE | ID: mdl-8289828

ABSTRACT

Rejoining of nonhomologous DNA termini plays a central role in processes of illegitimate recombination. In Xenopus egg extracts, DNA ends with noncomplementary 4-nucleotide antiparallel single-strand protrusions are assumed to be joined by formation of short mismatched overlap intermediates. The extents of these overlaps may be set by single fortuitously matching base pairs and determine the patterns of subsequent gap filling and nick ligation. Under conditions of alternative overlap settings, rules for the most probable joining pathway and the effects of mismatches on junction formation were analyzed. We show that in certain cases, fill-in and ligation converting overlap intermediates into covalently closed junctions may proceed in the presence of unrepaired mismatches, whereas in other cases, completion of junction formation is preceded by removal of mismatches. Results are discussed in relation with "alignment" proteins postulated to structurally support overlap heteroduplexes during junction formation.


Subject(s)
DNA/metabolism , Animals , Base Sequence , Cloning, Molecular , DNA/chemistry , DNA Restriction Enzymes/metabolism , Escherichia coli , Female , Molecular Sequence Data , Oocytes/metabolism , Restriction Mapping , Substrate Specificity , Xenopus laevis
18.
Planta Med ; (6): 542-3, 1986 Dec.
Article in English | MEDLINE | ID: mdl-17345497
SELECTION OF CITATIONS
SEARCH DETAIL
...