Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “DECELERATION”

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 415 records · Page 23Linked to original sources
PubMed2000

The rates of deceleration of nuclear and organellar DNA syntheses differ in the progenitor cells of the apical meristems during carrot somatic embryogenesis.

The synthesis of DNA in nuclei and organellar nucleoids at the various stages of somatic embryogenesis in carrot (Daucus carota L. cv. Kurodagosun) was analyzed using anti-5-bromo-2'-deoxyuridine (BrdU) immunofluorescence microscopy. The active syntheses of both nuclear and organellar DNA started in the cells forming the embryo proper 3 d after the initiation of embryogenesis, but not in cells forming suspensor-like cell aggregates. In the early globular embryo, active DNA syntheses were continuously observed in the whole embryo proper, except for the progenitor cells of the root apical meristem (RAM) and shoot apical meristem (SAM). These were recognized as slowly cycling cells with a non-BrdU-labelled nucleus and strongly BrdU-labelled organellar nucleoids. At the heart- and torpedo-shaped embryo stages, both nuclear and organellar DNA syntheses were inactive in the presumptive RAM and SAM. Thus, slowing down of organellar DNA synthesis is not coupled with, but is later than, that of nuclear DNA synthesis in the progenitor cells of the embryonic RAM and SAM. These findings clearly indicate that the timing of DNA synthesis is similar in the progenitor cells of both the RAM and SAM in the early stages of somatic embryogenesis.

Cell Nucleus↗
PubMed2003

Decelerating and sex-dependent tooth wear in Norwegian red deer.

In ungulates, tooth wear is often suggested as a proximate cause of senescence. Tooth wear is expected to be sex-dependent since energetic requirements and food selection varies largely between sexes in sexually dimorphic ungulates. Furthermore, tooth wear may lower mastication efficiency, and we predict a negative correlation between tooth wear and body weight or condition. We tested these predictions on data on tooth wear (estimated as height of first molar) of 1,311 male and 1,348 female red deer ( Cervus elaphus) aged 3-25 years and harvested along the west coast of Norway. The rate of tooth wear decreased with age. Males wear teeth at a higher rate (from 0.61 mm/year in 4-year olds to 0.45 mm/year in 11-year olds) than females (from 0.52 mm/year in 4-year olds to 0.39 mm/year in 11-year olds). Molar height correlated positively with body weight in both sexes, but not after adjusting for body size. Molar height was strongly dependent on body size in 3-year-old individuals (when tooth wear is minimal). Earlier reports in the literature of a positive correlation between tooth height and body weight may therefore be due to initial size differences rather than differences in condition due to tooth wear.

Aging↗
PubMed2005

Metformin decelerates aging and development of mammary tumors in HER-2/neu transgenic mice.

Transgenic FVB/N female mice carrying HER-2/neu mammary cancer gene received metformin (1200 mg/liter) with drinking water 5 days a week starting from the age of 2 months until natural death. Metformin slightly reduced food consumption, but did not change water consumption and dynamics of weight gain. Mean life span of mice increased by 8% (p<0.05), in 10% long-living mice it was prolonged by 13.1%, and the maximum life span was prolonged by 1 month under the effect of metformin in comparison with the control. The rate of populational aging decreased by 2.26 times. The total incidence of mammary adenocarcinoma and their multiplicity did not change under the effect of metformin, while the latency of tumor development increased and the mean diameter of tumors decreased. Hence, we first demonstrated a geroprotective effect of metformin and its suppressive effect towards the development of mammary tumors.

Adenocarcinoma↗
PubMed1982

Variable heart rate decelerations and transcutaneous PO2 during umbilical cord occlusion in fetal monkeys.

In five near-term monkeys under ketamine anesthesia, fetal heart rate, blood pressure, intrauterine pressure, and transcutaneous oxygen tension (tcPO2) were recorded continuously while the umbilical cord was occluded for 15 or 30 seconds. Fetal heart rate decreased 55 +/- 19 bpm, (mean +/- SD) and 78 +/- 20 bpm, respectively, with 15 and 30 second occlusions, while tcPO2 declined 6.0 +/- 1.6 and 11.5 +/- 3.3 torr, respectively. Fetal hypertension started promptly with cord occlusion and reached a maximum within 5 to 16 seconds; fetal blood pressure decreased thereafter and, in most instances, fell below the baseline until fetal heart rate began to recover. Fetal heart rate decreased within 1 to 2 seconds of cord occlusion, tcPO2 changes were the same, while heart rate changes were attenuated when the fetus was pretreated with 0.2 mg of atropine. These findings support a rapid and marked initial baroreceptor response, followed by a less marked chemoreceptor response. Thirty seconds following cord occlusion, PaO2 had returned to baseline, while tcPO2 was still 3 to 7 torr below baseline, indicating cutaneous vasoconstriction even though systemic blood pressure was normal. Relative heat output required to maintain the tcPO2 electrode temperature at 44 degrees C did not reflect alterations in skin perfusion during periods of cardiovascular change.

Animals↗