HISTOPHYSIOLOGICAL STUDIES ON THE CORPUS ALLATUM OF LEUCOPHAEA MADERAE. IV. ULTRASTRUCTURE DURING NORMAL ACTIVITY CYCLE.
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Activity Cycles↗
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Cell cycle activation of peripheral blood stem and progenitor cells expanded ex vivo with SCF, FLT-3 ligand, TPO, and IL-3 results in accelerated granulocyte recovery in a baboon model of autologous transplantation but G0/G1 and S/G2/M graft cell content does not correlate with transplantability.
Ex vivo expansion is a new strategy for hematopoietic stem and progenitor cell transplantation based on cytokine-induced amplification to produce grafts of controlled maturity. If the cell cycle position of CD34(+) cells has been reported to govern their engraftment potential, the respective role of stem and progenitor cells in short- and long-term hematopoietic recovery remains debated. Studies focused on long-term engraftment potential suggest impairment when using cultured grafts, but the capacity to sustain short-term recovery is still controverted. The aim of this study was: A) to evaluate the consequences of cell cycle activation on short and long-term engraftment capacity, and B) to determine if cell cycle status of grafts could predict hematopoietic recovery. We showed in a nonhuman primate model of autologous peripheral blood stem and progenitor cell transplantation that cell cycle activation of CD34(+) cells in the presence of stem cell factor + FLT3-ligand + thrombopoietin + interleukin 3 (six days of culture) which induced G1 and S/G2/M cell amplification (G0: 6.1% +/- 2.8%; G0/G1: 64.2% +/- 7.2%; S/G2/M: 30.4% +/- 7.3% respectively of expanded CD34(+) cells on average) resulted in the acceleration of short-term granulocyte recovery. By contrast, G0/G1 and S/G2/M cell content of expanded grafts did not correlate with short- or long-term engraftment.
Animals↗
Histone H3 transcription in Saccharomyces cerevisiae is controlled by multiple cell cycle activation sites and a constitutive negative regulatory element.
The promoters of the Saccharomyces cerevisiae histone H3 and H4 genes were examined for cis-acting DNA sequence elements regulating transcription and cell division cycle control. Deletion and linker disruption mutations identified two classes of regulatory elements: multiple cell cycle activation (CCA) sites and a negative regulatory site (NRS). Duplicate 19-bp CCA sites are present in both the copy I and copy II histone H3-H4 promoters arranged as inverted repeats separated by 45 and 68 bp. The CCA sites are both necessary and sufficient to activate transcription under cell division cycle control. A single CCA site provides cell cycle control but is a weak transcriptional activator, while an inverted repeat comprising two CCA sites provides both strong transcriptional activation and cell division cycle control. The NRS was identified in the copy I histone H3-H4 promoter. Deletion or disruption of the NRS increased the level of the histone H3 promoter activity but did not alter the cell division cycle periodicity of transcription. When the CCA sites were deleted from the histone promoter, the NRS element was unable to confer cell division cycle control on the remaining basal level of transcription. When the NRS element was inserted into the promoter of a foreign reporter gene, transcription was constitutively repressed and did not acquire cell cycle regulation.
Base Sequence↗
Phenotypic changes and cell cycle activation in early tubulointerstitial injury of rat adriamycin nephrosis.
Tubular response, including phenotypic changes against a variety of injuries, is an initial event that promotes tubulointerstitial injuries. Using the progressive kidney disease model of rat adriamycin (ADR) nephrosis, the present study focused on the cell cycle activation and phenotypic changes that occur in the tubuli in early tubulointerstitial injury in ADR nephrosis. At 12 weeks, experimental animals developed overt nephrosis with tubulointerstitial injury, which correlated well with the degree of proteinuria and incidence of glomerulosclerosis. Initial pathology of the tubuli showed a slight dilatation of tubuli, which tended to occur in individual nephrons. Immunohistochemistry demonstrated that vimentin-positive tubuli and osteopontin (OPN)-positive tubuli were associated mostly with proliferating cell nuclear antigen expression. Protein levels of OPN in the renal cortex were correlated with the level of proteinuria by western blotting. Vimentin- and OPN-expressing tubuli were tightly associated with a peritubular influx of alpha-smooth muscle actin (SMA)-positive cells or ED-1-positive cells. In addition, we found thrombomodulin+/ TUNEL+ (dUTP-biotin nick-end labeling) peritubular endothelial cells and ED-1+/alpha-SMA+ cells at an early stage among interstitial inflammatory cells. These results suggest that cell cycle activation in tubular cells forms the background for the phenotypic tubular changes that are involved in chronic tubulointerstitial injury in ADR nephrosis.
Actins↗
No basic rest-activity cycle in head, wrist or ankle.
Kleitman's theory of a Basic Rest-Activity Cycle (BRAC) was tested by recording activity of the head, wrists, and left ankle from 10 healthy subjects. No 90-100 min rhythms in activity were found.
Adult↗
[Rest-activity-cycle and stereotyped hand waving of a mentally defective child (author's transl)].
Stereotyped acts of a mentally defective girl. 6;6 years old, were observed from 6 a.m. till 8 p.m. during 16 days. Alternating phases of more or less frequent stereotyped hand waving showed a prominent periodicity of about 90 minutes. Sleep stages were also determined polygraphically during 10 nights. As statistically proved the mean peak-to-peak interval of the stereotyped activity at days corresponded to the mean REM- to REM period of nights. This suggests, that the stereotyped behavior of this child was driven by the basic rest activity cycle already described by Kleitman. The mean periodicity of sleep stages was represented by modeled rhythms adapted to the scored sleep stages. If the model rhythms of all 10 nights were extended backward to the preceding days, they paralleled the stereotyped activity. Half periods found in phase with REM stages corresponded to the maxima of the stereotyped activity. It will be discussed that the basic rest activity cycle triggers sensory as well as motor mechanisms characterizing both the phases of enhanced stereotyped activity and REM stages.
Behavior↗
GASTRIC ERODIONS IN THE RAT: EFFECTS OF IMMOBILIZATION AT DIFFERENT POINTS IN THE ACTIVITY CYCLE.
Predictable, cyclic patterns of activity were obtained from 30 male rats. Seventeen of these were subjected to physical immobilization just as they were approaching their period of peak activity and thirteen animals were restrained during the inactive phase of their cycle. Eight animals were found to have gastric erosions following the immobilization. All of these came from the group immobilized during the time they would have been in the active phase of their particular cycle.
Activity Cycles↗
Biochemistry of Fern Spore Germination: GLYOXYLATE AND GLYCOLATE CYCLE ACTIVITY IN ONOCLEA SENSIBILIS L.
In chlorophyll-containing spores of Onoclea sensibilis, depletion of lipid reserves during germination is correlated with increases in the activity of the glyoxylate cycle enzymes isocitrate lyase and malate synthase. In Onoclea, the heterotrophic activity associated with lipid catabolism occurs at the same time that autotrophic activity is taking place. Increases in chlorophyll content and in the activity of glycolate oxidase were recorded during the earliest stages of spore germination. In this species, there is no temporal separation of heterotrophic and autotrophic reactions. Concurrent increases in glyoxylate and glycolate cycle activities appear to occur naturally.
Journal Article↗
Diurnal variations in resting-active cycles in full-term fetal heart rate changes.
To elucidate the mechanism of the resting-active cycles (RAC) of fetal heart rates (FHR), in the resting and non-resting phases (RP and NRP), 24-h FHR recordings were made on 16 normal full-term pregnant women. RP, NRP, RAC-1 (NRP-NRP cycle), and RAC-2 (RP-RP cycle) were defined based on the criteria of Nijhuis et al. Frequency distributions were plotted separately for the entire 24-h period as well as for the day-time (07:00-21:00 h) and night-time (21:00-07:00 h), and were compared using Kolmogorov-Smirnov two-sample tests. The mean durations (+/- S.D.) (min) of RP, NRP, RAC-1, and RAC-2 were 22.7 +/- 11.2, 67.3 +/- 47.2, 90.0 +/- 47.6, and 89.9 +/- 48.6 during 24-h periods, 20.1 +/- 7.7, 68.3 +/- 52.3, 88.6 +/- 53.1, and 88.4 +/- 53.0 during the day-time, and 25.4 +/- 13.2, 66.2 +/- 41.2, 91.4 +/- 41.0, and 91.5 +/- 43.4 during the night-time. Length of RP was the only factor significantly different during the day and night (P < 0.05). We propose that there are different mechanisms controlling RP and NRP.
Activity Cycles↗
Efficient Salmonella entry requires activity cycles of host ADF and cofilin.
Entry of Salmonella into mammalian cells is strictly dependent on the reorganization of actin cytoskeleton induced by a panel of Salmonella type III secreted proteins. Although several factors have been identified to be responsible for inducing the actin polymerization and stability, little is known about how the actin depolymerization contributes to Salmonella-induced actin rearrangements. We report here that activity cycles of host actin depolymerizing factor (ADF and cofilin) are modulated by Salmonella during bacterial entry. Efficient Salmonella internalization involves an initial dephosphorylation of ADF and cofilin followed by phosphorylation, suggesting that ADF and cofilin activities are increased briefly. Expression of a kinase dead form of an ADF/cofilin kinase (LIM kinase 1) or a catalytically inactive ADF/cofilin phosphatase (Slingshot), but not constitutively active LIM kinase 1 or wild-type Slingshot, resulted in decreased invasion. These data suggest that ADF/cofilin activities play a key role in the actin polymerization/depolymerization process induced by Salmonella. The activation of ADF/cofilin is brief and has to be reversed to facilitate efficient bacterial entry. Surprisingly, co-expression of constitutive active ADF and cofilin prevented efficient Salmonella entry, whereas expression of either one alone had no effect. We propose that ADF and cofilin actin-dynamizing activities and their activity cycling via phosphorylation are required for efficient Salmonella internalization.
Actin Depolymerizing Factors↗
Intrauterine growth retardation is associated with reduced cell cycle activity, but not myofibre number, in ovine fetal muscle.
Cellular development of muscle was studied in sheep fetuses at 85 days of gestation. Large and small fetuses were compared at 100, 115 and 130 days, and an additional group of large 130-day fetuses were studied following 7 days of maternal undernutrition. Myogenesis in the peroneus longus muscle was completed between 100 and 115 days of gestation, and myofibre number did not differ between small and large fetuses. The proportion of myofibre-related nuclei identified as entering S-phase of the cell cycle was 1.7% per hour in 85-day fetuses. In large fetuses, subsequent rates were relatively constant (approximately 1.5% h(-1)), whereas in small fetuses cell cycle activity declined with age from 1.3 to 0.9% h(-1), and was 0.5% h(-1) in 130-day fetuses of restricted ewes. The constant rate of cell cycle activity in large fetuses was associated with an increasing estimated rate of muscle growth (peroneus longus (mg) = 0.831 x 10(0.024 x age [d]), r2 = 0.98), which contrasted with slow and relatively constant muscle accretion in small fetuses (8.4 mg day(-1)), and slower muscle accretion at 130 days in large fetuses from restricted ewes. Differences in DNA and RNA content in the semimembranosus muscle increased with age, large fetuses having 70% more muscle DNA, 108% more muscle RNA and 104% larger muscles than small fetuses at 130 days (all P<0.001). The results demonstrate that myonuclei accumulation, but not myofibre number, is associated with fetal growth in sheep and, therefore, with fetal nutrition during mid to late gestation.
Animals↗
The active cycle of breathing techniques--to tip or not to tip?
The active cycle of breathing techniques (ACBT) in gravity-assisted drainage positions is an effective airway clearance regimen for individuals who produce excess bronchial secretions. This study compared the ACBT in positions with and without a head-down tilt. Nineteen subjects (11 men), mean age 37.1 years (range 18-76 years), with bronchiectasis who produced more than 20 g of sputum per day and had a mean forced expiratory volume in 1 s (FEV1) of 56.9% predicted (range 23-90% pred.) were studied. There was no significant difference in the wet weight of sputum expectorated when using the ACBT in gravity-assisted drainage positions with or without a head-down tilt. Mean (SD) score for perception of breathlessness, measured on a visual analogue scale, increased significantly following treatment with a head-down tilt [2.3 (1.6) to 3.3 (2.0) cm, P = 0.02]. There was no significant difference in oxygenation or lung function (FEV1). Eighteen subjects preferred the ACBT without a head-down tilt. The ACBT in the horizontal position is a simple airway clearance regimen suitable for individuals who produce greater than 20 g of sputum per day. Subjects were less breathless and preferred the ACBT in the horizontal position, thus providing a treatment alternative that may improve adherence in individuals who are required to carry out daily airway clearance treatments.
Adolescent↗
A note on the activity cycle of captive white-fronted lemurs (Eulemur fulvus albifrons).
We studied the activity cycle of captive-born white-fronted lemurs (Eulemur fulvus albifrons) at Zurich Zoo with the aim to discuss current hypotheses on the evolution of cathemerality in lemurs. In contrast to their relatives in the wild, these lemurs were active exclusively during the day. If cathemerality is a strategy to increase food intake or to avoid predators, then nocturnal activity is not essential for captive animals and may be suppressed simply due to the absence of stimuli. This suggests that cathemerality includes a distinct element of flexibility regarding the distribution of diurnal and nocturnal activity, with the option to omit nightly activities.
Animals↗
Physiological interactions of the basic rest--activity cycle of the brain: pulsatile luteinizing hormone secretion as a model.
The hypothesis of the "basic rest--activity cycle" (BRAC) as an ultradian rhythm of CNS activity which integrates many somatic, visceral, and behavioral functions is supported by a variety of studies which demonstrate similar periodicities in the expression of a remarkable number of critical physiological systems. However, the existence of this BRAC has been supported primarily only by this similarity in cyclicity, and the argument in support of this potentially meaningful CNS oscillator is thus largely inferential. Since resolving consistent temporal relationships between a variety of these apparently otherwise unrelated rhythmic functions would strongly support the hypothesized existence of the BRAC, this article first presents methodology for reliable evaluation of these difficult to analyze interactions. Then, a relationship between rhythmic physical activity and pulsatile luteinizing hormone (LH) secretion is employed as a model interaction which allows analysis of the rhythmicity of the BRAC itself. This BRAC entrainment of pulsatile LH secretion is also utilized as a model to demonstrate how the BRAC may modulate the activity of various physiological functions via relatively direct mechanisms, secondary interactions, or entrainment of tissue with its own intrinsic pacemaker activity. The physiological function of the BRAC is discussed relative to this entrainment of pulsatile LH release.
Animals↗
Synthesis and deformylation of Staphylococcus aureus delta-toxin are linked to tricarboxylic acid cycle activity.
In bacteria, translation initiates with formyl-methionine; however, the N-terminal formyl group is usually removed by peptide deformylase, an enzymatic activity requiring iron. Staphylococcus aureus delta-toxin is a 26-amino-acid polypeptide secreted predominantly with a formylated N-terminal methionine, which led us to investigate regulation of delta-toxin deformylation. We observed that during exponential and early postexponential growth, delta-toxin accumulated in the culture medium in formylated and deformylated forms. In contrast, only formylated delta-toxin accumulated after the early postexponential phase. The transition from producing both species of delta-toxin to producing only formyl-methionine-containing delta-toxin coincided with increased tricarboxylic acid (TCA) cycle activity. The TCA cycle contains several iron-requiring enzymes, which led us to hypothesize that TCA cycle induction depletes the iron in the culture medium, thereby inhibiting peptide deformylase activity. As expected, S. aureus depletes the iron in the culture medium between the postexponential and stationary phases of growth. Inhibition of delta-toxin deformylation was relieved by TCA cycle inactivation or by addition of supplemental iron to the culture medium. Of interest, peptides containing formyl-methionine are potent chemoattractants for neutrophils, suggesting that delta-toxin deformylation may have functional consequences. We found neutrophil chemotactic activity only with formylated delta-toxin. The S. aureus TCA cycle is derepressed upon depletion of rapidly catabolizable carbon sources; this coincides with the transition to producing only formylated delta-toxin and results in an increased inflammatory response. The proinflammatory response should increase host cell damage and result in the release of nutrients. Taken together, these results establish that there is an important linkage between bacterial metabolism and pathogenesis.
Amidohydrolases↗
Agreement between polar and SRM mobile ergometer systems during laboratory-based high-intensity, intermittent cycling activity.
The purpose of this study was to assess the agreement between two mobile cycle ergometer systems for recording high-intensity, intermittent power output. Twelve trained male cyclists (age 31.4 +/- 9.8 years) performed a single 3 min intermittent cycle test consisting of 12 all-out efforts, separated by periods of passive recovery ranging from 5 to 15 s. Power output was recorded using a Polar S710 heart rate monitor and power sensor kit and an SRM Powercrank system for each test. The SRM used torque and angular velocity to calculate power, while the S710 used chain speed and vibration to calculate power. Significant differences (P < 0.05) in power were found at 8 of the 12 efforts. A significant difference (P = 0.001) was also found when power was averaged over all 12 intervals. Mean power was 556 +/- 102 W and 446 +/- 61 W for the SRM and S710 respectively. The S710 underestimated power by an average of 23% with random errors of */[division sign] 24% when compared with the SRM. Random errors ranged from 36% to 141% with a median of 51%. The results indicate there was little agreement between the two systems and that the Polar S710 did not provide a valid measure of power during intermittent cycling activity when compared with the SRM. Power recorded by the S710 system was influenced greatly by chain vibration and sampling rates.
Adult↗
Soybean (Glycine max. L.) and bacteroid glyoxylate cycle activities during nodular senescence.
Soybean (Glycine max. L.) nodular senescence results in the dismantling of the peribacteroid membrane (PBM) and in an increase of soybean isocitrate lyase (ICL; EC 4.1.3.1) and malate synthase (MS; EC 4.1.3.2) mRNA and protein levels. This suggests that in senescing soybean nodular cells, the specific glyoxylate cycle enzyme activities might be induced to reallocate carbon obtained from the PBM degradation. In order to evaluate as well the carbon metabolism of the nitrogen-fixing Bradyrhizobium japonicum endosymbiotic bacteroids during nodular senescence, their glyoxylate cycle activities were also investigated. To this end, partial DNA sequences were isolated from their icl and ms genes, but the corresponding mRNAs were not detected in the microorganisms. It was also observed that the bacteroid ICL and MS activities were negligible during nodular senescence. This suggests that glyoxylate cycle activities are not reinitiated in the bacteroids under these physiological conditions. In case the microorganisms nevertheless feed on the PBM degradation products, this might occur via the citric acid cycle exclusively.
Bradyrhizobium↗
Plasma melatonin exhibits a diurnal secretion in the common marmoset (Callithrix jacchus): relationship to the rest-activity cycle.
The secretion of plasma melatonin exhibits a diurnal variation in the common marmoset (Callithrix jacchus jacchus) (n = 12) with mean values of 125.8 fmol/ml during darkness and below assay sensitivity (mean 70.5 fmol/ml) during the light period. Both melatonin secretion and the rest activity cycle appeared to be phase advanced with relation to the light dark cycle which is consistent with an endogenous circadian period (tau) of less than 24 h in this species.
Activity Cycles↗