Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “DNA Fragmentation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 757 records · Page 42Linked to original sources
PubMedDate not supplied

Immunohistochemistry of DNA fragmentation factor in human stomach and colon: its correlation to apoptosis.

DNA fragmentation factor (DFF) is an important factor in the pathway leading to apoptosis, which is activated by caspase-3 and is involved in the formation of nuclear DNA fragments. DFF is a heterodimic protein of 40kDa and 45kDa that becomes activated when DFF is cleaved by caspase-3. Of the two enzymatically cleaved fragments of DFF, it is the 40kDa fragment (DFF40) that is the active component of DFF and is responsible for triggering chromatin condensation when incubated with nuclei. However, the topological correlation between apoptosis and DFF expression in human tissues has not been examined. Therefore, in this study, we first immunolocalized DFF in non-neoplastic mucosa, hyperplastic polyp, adenoma and carcinoma of human stomach and colon. We then examined apoptosis in serial tissue sections. Labeling index (LI) of DFF and TUNEL positive cells in the same areas of serial tissue sections were obtained using computer-assisted image analysis. In the stomach, the DFF LI in non-neoplastic mucosa (9.8 +/- 5.0%, n = 3) and carcinoma (18.2 +/- 3.6, n = 3) were significantly lower than that of hyperplastic polyp (73.3 +/- 9.2%, n = 3) and adenoma (66.5 +/- 18.3%, n = 3) [p < 0.0001]. In colon, the DFF LI in non-neoplastic mucosa (10.2 +/- 6.4%, n = 3) was significantly lower than that of hyperplastic polyp (56.0 + 34.7%, n = 3) [p = 0.0013] and adenoma (30.1 +/- 16.3%, n = 3) [p = 0.0037]. Cells positive for DFF were much more widely distributed than TUNEL positive cells in both non-pathologic and pathologic mucosa of human stomach and colon. Notably, DFF positive cells were present beneath the TUNEL positive cells in non-pathological gastric and colonic epithelium. In addition, there was a significant positive correlation between DFF and TUNEL LIs in human stomach and colon [p < 0.0001]. These results suggest that DFF may be involved in the process of apoptosis in human gastric and colonic mucosa.

Apoptosis↗
PubMed1993

Internucleosomal DNA fragmentation and programmed cell death (apoptosis) in the interdigital tissue of the embryonic chick leg bud.

In this work we have attempted to characterize the programmed cell death process in the chick embryonic interdigital tissue. Interdigital cell death is a prominent phenomenon during limb development and has the role of sculpturing the digits. Morphological changes in the regressing interdigital tissue studied by light, transmission and scanning electron microscopy were correlated with the occurrence of internucleosomal DNA fragmentation, evaluated using agarose gels. Programming of the cell death process was also analyzed by testing the chondrogenic potential of the interdigital mesenchyme, in high density cultures. Our results reveal a progressive loss of the chondrogenic potential of the interdigital mesenchyme, detectable 36 hours before the onset of the degenerative process. Internucleosomal DNA fragmentation was only detected concomitant with the appearance of cells dying with the morphology of apoptosis, but unspecific DNA fragmentation was also present at the same time. This unspecific DNA fragmentation was explained by a precocious activation of the phagocytic removal of the dying cells, confirmed in the tissue sections. From our observations it is suggested that programming of cell death involves changes before endonuclease activation. Further, cell surface changes involved in the phagocytic uptake of the dying cells appear to be as precocious as endonuclease activation.

Animals↗
PubMed1996

Apoptosis and DNA fragmentation in the bulbus cordis of the developing rat heart.

Histologic, ultrastructural and nick end labeling studies were made of the process of apoptosis in the bulbus cordis of rat embryos. Apoptosis was observed between the 14th and 16th days of gestational age, at which time the bulbus cordis undergoes extensive remodeling. Three types of mesenchymal cells were identified in this region: cells undergoing apoptosis, cells engaging in the phagocytic removal of apoptotic cells, and cells not involved in either of these two processes. Fragmentation of DNA, demonstrated by nick end labeling, was found only in the apoptotic cells. The combined use of morphologic and labeling techniques is extremely useful in the evaluation of the contribution of apoptosis to cardiac morphogenesis.

Animals↗
PubMed1997

Involvement of apoptosis and lysosomal hydrolase activity in the oviducal regression during induced molting in chickens: a cytochemical study for end labeling of fragmented DNA and acid phosphatase.

Induced molting improves egg producing functions in hens. We investigated the mechanism of oviducal regression during induced molting. Involvement of apoptosis and autolysis in the oviducal regression process was analyzed by terminal deoxynucleotidyl transferase (T'dt)-mediated biotinylated deoxyuridine triphosphates (dUTP) nick end-labeling TUNEL) and an enzyme histochemistry for acid phosphatase. Nuclei positive for TUNEL were negligible and acid phosphatase staining was weak in the oviduct of laying hens. The frequency of TUNEL-positive nuclei was significantly increased in tubular gland cells of magnum, isthmus, and shell gland 2 d after cessation of egg laying and significantly decreased thereafter. The intensity of acid phosphatase staining was gradually increased during oviducal regression and extremely high on Day 7 after cessation of egg laying. These results suggest that during oviducal regression in induced molting hens, apoptosis is induced in the earlier stage of oviducal regression and autolysis occurs thereafter eventually, the glandular cells disappear.

Acid Phosphatase↗
PubMedDate not supplied

Elevated levels of fragmented DNA nucleosomes in native and activated lymphocytes indicate an enhanced sensitivity to apoptosis in sporadic Alzheimer's disease. Specific differences to vascular dementia.

Apoptotic cell death is thought to be the most likely mechanism of cell death contributing to neurodegeneration in Alzheimer's disease (AD). Here, we provide evidence that in sporadic AD cases the vulnerability of peripheral cells to undergo apoptosis is increased compared to non-demented elderly controls and, very importantly, to patients with subcortical vascular encephalopathy (SVE) as another, but demented control group. Quiescent 'native' and 'activated' lymphocytes from AD patients that were predisposed to commit apoptotic cell death by priming the cells with interleukin-2, are shown to accumulate apoptosing cells to a significantly higher extent in spontaneous and in oxidative stress-induced in vitro apoptosis. Our results demonstrate robust differences in cell death sensitivity between AD and vascular dementia. In none of the conditions investigated, lymphocytes from SVE patients were significantly different from non-demented controls. The comparable findings of a higher extent of apoptotic features in neurons and in peripheral blood cells of AD patients are remarkable and may suggest a rather general modulation of apoptotic mechanisms by the disease, which even can be picked up at the level of peripheral lymphocytes under specific in vitro conditions.

Aged↗
PubMed1988

[Complementary addressed modification of single- and double-stranded DNA by alkylating derivatives of oligonucleotides isolated by partial DNA fragmentation].

Reagents for complementary addressed modification of nucleic acids are proposed to be synthesized on the base of oligonucleotides obtained by partial chemical fragmentation of DNA. The alkylating 4-(N-2 chlorethyl-N-methylamino) benzyl-5'-phosphamide derivatives of 5'-[32P]-labelled oligonucleotides obtained from single and double-stranded DNA cloned in bacteriophage M13 mp9 have been synthesized. The alkylated derivatives of oligonucleotides selectively modify the complementary tracts of single-stranded DNA-target. They are also able to modify the complementary regions in double-stranded supercoiled plasmid DNA.

Alkylating Agents↗
PubMedDate not supplied

[The electrophoretic properties of gels of high-resolution MS-4 agarose for separating DNA fragments in molecular genetic analysis].

The Hispanlab firm (Spain) offers a new series of Molecular Screen analytical agarose, including MS-4 agarose intended for separation of small fragments of DNA. This low-endosmotic agarose attracts attention as a probable alternative to well-known FMC Bio Products special agarose (USA) due to its useful properties. We characterized a gel-electrophoretic system based on MS-4 agarose (and its correspondence to its passport) and tested its fitness for standard molecular genetic expert investigations. The following parameters were assessed: mechanical properties of gel, its transparency, degree of background fluorescence upon ethidium bromide staining, resolving power, and position distortions in the electrophoregram. Important features of MS-4 agarose gels were detected, not typical of other agarose systems, which should be borne in mind during investigations with this agarose.

DNA↗
PubMed1998

Effects of prefixation and fixation times on apoptosis detection by in situ end-labeling of fragmented DNA.

OBJECTIVE: Apoptosis is considered to play an important role in the pathogenesis and progression of neoplasia. An in situ 3'-end DNA labeling (TUNEL) method was recently developed and has been widely used to identify apoptotic cells in tissue sections. However, sometimes the TUNEL method labels many more cells than expected. We investigated the effects of prefixation time and fixation time on the apoptotic index detected by this method. MATERIALS AND METHODS: Using the spleen and thymus of rats, the effects of prefixation time (0, 1, 2, 4, 6, 12, 24, 48, and 72 hours) at 4 degrees C and fixation time (6, 12, 24, 48, 72, and 96 hours; 1, 2, and 3 weeks) on the apoptotic index were examined by the TUNEL method. Agarose gel electrophoresis of extracted DNA from the specimens of each prefixation time was also performed. RESULTS: In comparison with control tissue (no prefixation time), which showed scattered positive cells with distinct staining restricted to the nucleus, the splenic tissue unfixed for 2 hours or more and the thymic tissue unfixed for 4 hours or more showed cytoplasmic staining in the positive cells. Moreover, as the prefixation time was prolonged, the number of positive cells gradually increased. Agarose gel analysis of DNA extracted from tissue sections left unfixed longer than 24 hours showed a ladder pattern consisting of multiples of about 200 base pairs. CONCLUSIONS: Two hours was the limit of prefixation time for the precise identification of apoptosis by the TUNEL method. The false-positive cells in tissue sections left unfixed for longer time intervals may have been due to internucleosomal DNA cleavage following necrosis. In contrast, the length of fixation time in buffered formalin seemed to have no effect on the results obtained by this method.

Animals↗
PubMed1999

Suppression of ethanol-induced apoptotic DNA fragmentation by geranylgeranylacetone in cultured guinea pig gastric mucosal cells.

The purpose of this study was to elucidate the molecular mechanism of action of geranylgeranylacetone, an antiulcer drug. Treatment with ethanol for 8 hr at the optimum concentration (7.5%) caused apoptotic DNA fragmentation in cultured guinea pig gastric mucosal cells. Pretreatment of cells with geranylgeranylacetone suppressed the DNA fragmentation in a dose-dependent manner. The maximum effect was achieved at 10(-6) M, at which concentration the drug was previously shown to induce heat-shock proteins. The suppression required an incubation period longer than 1 hr. Pretreatment of cells with low concentrations of ethanol also prevented DNA fragmentation.

Animals↗
PubMed2000

Formation of the base modification 8-hydroxyl-2'-deoxyguanosine and DNA fragmentation following seizures induced by systemic kainic acid in the rat.

The formation of oxidative DNA damage as a consequence of seizures remains little explored. We therefore investigated the regional and temporal profile of 8-hydroxyl-2'-deoxyguanosine (8-OHdG) formation, a hallmark of oxidative DNA damage and DNA fragmentation in rat brain following seizures induced by systemic kainic acid (KA). Formation of 8-OHdG was determined via HPLC with electrochemical detection, and single- and double-stranded DNA breaks were detected using in situ DNA polymerase I-mediated biotin-dATP nick-translation (PANT) and terminal deoxynucleotidyl-transferase-mediated nick end-labeling (TUNEL), respectively. Systemic KA (11 mg/kg) significantly increased levels of 8-OHdG within the thalamus after 2 h, within the amygdala/piriform cortex after 4 h, and within the hippocampus after 8 h. Levels remained elevated up to sevenfold within these areas for 72 h. Smaller increases in 8-OHdG levels were also detected within the parietal cortex and striatum. PANT-positive cells were detected within the thalamus, amygdala/piriform cortex, and hippocampus 24-72 h following KA injection. TUNEL-positive cells appeared within the same brain regions and over a similar time course (24-72 h) but were generally lower in number. The present data suggest oxidative damage to DNA may be an early consequence of epileptic seizures and a possible initiation event in the progression of seizure-induced injury to DNA fragmentation and cell death.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1989

Nucleotide sequence and transcriptional studies of the vaccinia virus KpnI I DNA fragment.

The nucleotide sequence of the vaccinia virus (VV) KpnI I DNA fragment has been determined. This central, highly conserved portion of the VV genome corresponds to the right portion of the HindIII E, all of the HindIII O and P, and the left portion of the HindIII I DNA fragments. Computer-assisted analysis of this data indicated the presence of five tandemly oriented, leftward-reading open reading frames (ORFs) I-4, I-3, I-2, I-1, and O-1, with the I-4 ORF being an immediate early gene encoding the large M1 subunit of VV ribonucleotide reductase. Transcriptional analyses suggested that the I-3 and O-1 genes were constitutive genes, being expressed both before and after viral DNA synthesis. The I-1 and I-2 genes were late genes, expressed only after the initiation of viral DNA synthesis. Cell-free translation was used to confirm that the I-3, I-1, and O-1 ORFs were bonafide messages encoding proteins with molecular weights of 30, 35, and 71 kD, respectively. When the predicted amino acid sequences of the proteins encoded by the I-3, I-2, I-1, and O-1 genes were compared to the Genbank data base, no significant alignments were detected. Therefore, the biological functions of these proteins in the VV life cycle remain to be established.

Amino Acid Sequence↗