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PubMed1990

Use of ultrasonic Doppler waveforms to estimate changes in uterine artery blood flow and vessel compliance.

Previous data from our laboratory have demonstrated that uterine blood flow (UBF) and uterine arterial smooth muscle tone vary regularly during the estrous cycle of the cow. Uterine blood flow is highest and uterine arterial tone is lowest at estrus, whereas UBF is lowest and uterine arterial tone is highest during the luteal phase of the cycle. Blood flow through arteries is highly pulsatile; changes in arterial wall properties affect shape of the velocity waveform. This study was conducted to evaluate changes in uterine arterial velocity waveforms throughout the estrous cycle of the cow and to relate these changes to fluctuations in UBF and concentrations of estrogen and(or) progesterone in systemic blood. Pulsatile velocity waveforms were obtained daily from pulsed-wave ultrasonic probes placed surgically on the middle uterine artery of five beef cows exhibiting estrous cycles of normal duration (d 0 = day of estrus). Velocity waveforms varied regularly during the estrous cycle of each cow in association with changes in UBF and steroid concentrations. Further, two distinct velocity waveform shapes were observed during the estrous cycle. The first waveform shape, which was observed during periods of high UBF (d -4 to +4 of the estrous cycle), was characteristic of a highly compliant vessel and was associated with a high estrogen:progesterone ratio. The second waveform shape, which was observed from d 7 to 14 of the estrous cycle, was characteristic of a less compliant vessel and was associated with a depressed estrogen:progesterone ratio. These data suggest that compliance of the uterine artery changes during the estrous cycle in association with the changing estrogen:progesterone ratio in blood.

Animals↗
PubMed1986

Estrogen modulation of uterine adrenergic-cholinergic interaction: effects on vasoactivity and adrenergic receptors in the guinea pig.

The regulation of uterine blood flow (UBF) in the guinea pig was investigated by determining the effects of steroid-catecholamine interaction on guinea pig UBF in cyclic (Day 0 = estrus) and ovariectomized (OVX)-steroid treated females. In cyclic guinea pigs, parallel elevations in uterine weight, UBF, beta and alpha receptor levels were observed during the estrus period, whereas uterine norepinephrine (NE) levels were low. In contrast, all parameters remained at low levels except NE levels during the luteal phase of the cycle which remained elevated in both normal and OVX-oil treated animals. Estrogen (E1)-treated females showed elevated uterine weights, UBF, beta, and alpha receptor levels but low uterine NE concentrations. Combined progesterone-estrogen (P2E1) treatment caused similar changes but maintained tissue NE at control levels. In the exposed uterine artery preparation, the sequential administration of acetylcholine followed by NE application induced a marked elevation in UBF in OVX, E-1-treated animals which was blocked by phentolamine (10(-6) M). This phenomena could not be demonstrated in either oil- or progesterone-treated OVX guinea pigs. In uterine membrane preparations from ovariectomized guinea pigs pretreated with either oil or progesterone, methacholine (cholinergic agonist; 10(-6) M) failed to alter the affinity of the alpha receptor for NE. However, in uterine preparations from OVX, estradiol-treated guinea pigs, methacholine significantly (P less than .05) increased the affinity of the alpha receptor for NE.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1994

[Effects of vibration on uterine circulation in pregnant rats].

With the recent remarkable development of transportation facilities, pregnant women are frequently exposed to mechanical vibration. To experimentally demonstrate that vibration disorders normal pregnancy, uterine blood flow (UBF) and the several kinds of endocrine indicators were examined in pregnant rats exposed to vibration (10m/s2, 8Hz, 90 min). The exposure to vibration decreased UBF in the rats significantly. The UBF of the rats pretreated with peritoneal administration of angiotensin II (AII) was increased when they were not exposed to vibration. In contrast to this, in AII pretreated rats simultaneously exposed to vibration, a significant decrease in the UBF was recognized. Vibration decreased the plasma level of progesterone (PRO), but pretreatment with AII induced no difference in PRO in vibration-exposed and unexposed rats. The level of prostaglandin E2 (PGE2) was decreased in rats exposed to vibration, but not in control rats. Pretreatment with AII still decreased PGE2 in rats exposed to vibration. These results indicate that vibration may play an important role in the development of abnormal pregnancy through uterine circulatory and ovarian dysfunctions. It seems that a decrease in UBF is induced primarily via an inhibitory effect of vibration on PGE2, and secondarily via a direct action on the uterus.

Animals↗
PubMed1998

Nucleolar function and size in cancer cells.

We have have studied the relationship between nucleolar function and size and cell doubling time in cancer cells. Seven human cancer cell lines characterized by different proliferation rates were used. Nucleolar functional activity was evaluated by measuring RNA polymerase I activity and expression of RNA polymerase I upstream binding factor (UBF), DNA topoisomerase I, and fibrillarin, three proteins involved in synthesis and processing of rRNA. Transcriptional activity of RNA polymerase I was strictly related to cell doubling time (r = -0.97; P < 0.001). The quantitative distribution of UBF, DNA topoisomerase I, and fibrillarin was evaluated on Western blots using specific monoclonal antibodies by densitometric analysis of autoradiographic signals. It was found to be directly related to RNA polymerase I transcriptional activity (r = 0.89, P = 0.008 for UBF; r = 0.95, P = 0.001 for DNA topoisomerase I; and r = 0.91, P = 0.004 for fibrillarin) and inversely related to cell doubling time (r = -0.87, P = 0.011 for UBF; r = -0.97, P < 0.001 for DNA topoisomerase I; and r = -0.91, P = 0.005 for fibrillarin). The nucleolar areas were measured by automated image analysis on toluidine blue-stained cells. The values of the stained nucleolar structures per cell were directly related to RNA polymerase I transcriptional activity (r = 0.94, P = 0.001) and inversely related to cell doubling time (r = -0.98, P < 0.001). The same area values of the nucleolar structures stained by toluidine blue were also closely related to the amount of UBF (r = 0.92, P = 0.003), DNA topoisomerase I (r = 0.98, P < 0.001), and fibrillarin (r = 0.95, P = 0.001), and to the in situ quantitative distribution of AgNOR proteins (r = 0.98, P < 0.001). Our results demonstrated that in cancer cells rRNA transcriptional activity and nucleolar size are inversely related to cell doubling time. Quantitative distribution of nucleolar structures within the cell represents a cytohistological parameter of the rapidity of cell proliferation.

Blotting, Western↗
PubMed1992

Mouse rRNA gene transcription factor mUBF requires both HMG-box1 and an acidic tail for nucleolar accumulation: molecular analysis of the nucleolar targeting mechanism.

RNA polymerase I requires at least two nucleolar transcription factors, UBF and SL-1, for ribosomal RNA gene (rDNA) transcription. UBF requires SL-1 for the formation of a stable initiation complex on the rDNA promoter region. We have determined the region of mouse UBF (mUBF) required for nucleolar targeting. Although mUBF has a nuclear localization sequence, this sequence alone is not sufficient for mUBF to accumulate in the nucleolus. Deletion analyses show that mUBF requires a wide region except for the N-terminal 101 amino acids for nucleolar targeting. Deletion of either the HMG-box1, a region crucial for rDNA binding, or the acidic tail, a region that may interact with SL-1, results in the loss of nucleolar targeting. We show by DNA affinity analysis that the HMG-box1 is absolutely necessary for mUBF to bind to the upstream control element of the rDNA. We also show that mUBFs with various internal deletions retain both nucleolar targeting and DNA binding ability. A clear correlation was demonstrated between the DNA binding and nucleolar targeting ability. These results suggest that UBF is transferred to the nucleus by its NLS and is sequestered in the nucleolus by its specific and stable binding to the rDNA promoter via HMG-boxes and the acidic tail.

Animals↗
PubMed2005

How do recovery advice and behavioural characteristics influence upper-body function and quality of life among women 6 months after breast cancer diagnosis?

GOALS OF WORK: After breast cancer treatment, women may experience significant and enduring problems relating to upper-body function (UBF) and quality of life (QoL). Women are often given advice to avoid problems, despite little scientific evidence to support or refute the advice given. PATIENTS AND METHODS: This study addressed the relationships between recovery advice and subsequent behaviours on QoL (Functional Assessment of Cancer Therapy, Breast questionnaire) and UBF (Disability of Arm, Shoulder and Hand questionnaire) 6 months after treatment for unilateral breast cancer among a population-based sample of women residing in southeast Queensland (n=287). MAIN RESULTS: Eighty-seven percent (n=249) of women reported that they received advice on facilitating arm function during their hospital stay, whereas 72% received subsequent recovery advice from medical and/or allied health professionals. Reported QoL and UBF were similar between groups, irrespective of advice received. Behaviours of interest included adherence to advice given, participation in breast cancer programmes and whether women had flight travel, used the treated side as much as the untreated side or had trauma, sunburn, injections and/or blood pressure readings on the treated side in the previous 6 months. QoL and UBF were highest among those who followed minimal advice, who used their treated side as much as their untreated side and who did not participate in any breast cancer programme (p<0.05). CONCLUSIONS: The findings neither support nor refute current recommendations made to women with breast cancer, but rather raise questions about the value of this recovery advice. The study also provides novel findings regarding relationships between certain behaviours and QoL among breast cancer survivors.

Activities of Daily Living↗
PubMed1978

The effect of prostaglandins and other vasoactive substances on uterine blood flow and myometrial activity.

The effects of prostaglandins (PG's), bradykinin, and adenosine on uterine blood flow (UBF) and intrauterine pressure (IUP) were investigated in conscious oophorectomized ewes. PGE1 and adenosine increased UBF to levels comparable to those induced by estradiol-17beta, whereas PGE2 and PGA1 achieved only 20 and 36 per cent of peak estradiol-induced levels, respectively. PGE1, PGE2, and adenosine all caused transient increases in IUP while PGA1 had no effect on myometrial activity. Bradykinin increased UBF to 60 per cent of peak estradiol-induced levels, with concomitant increases in IUP tonus. PGE2 and PGF2alpha decreased peak estrogen-induced UBF by 50 and 70 per cent, respectively, while inducing related increases in IUP. When compared with oxytocin, the effects of PGE2 at high flow appeared to be mediated only my myometrial activity, whereas PGF2alpha apparently caused vasoconstriction as well. These findings support the concept that PGE1 could play a role in mediating estrogen-induced uterine vasodilatation.

Adenosine↗
PubMed1979

Responses of the gravid uterine vasculature to arterial levels of local anesthetic agents.

Responses of the uterine vasculature and myometrium to uterine arterial infusions of local anesthetic agents were evaluated in chronically prepared conscious ewes between 86 and 141 days of gestation. Decreases in uterine blood flow (UBF) with increasing levels of anesthetic drugs were similar to those previously observed in nonpregnant ewes. A 25% decrease in UBF occurred at 7 micrograms of bupivacaine, 11.5 micrograms of 2-chloroprocaine, and 19.5 micrograms of lidocaine per milliliter of control UBF. Myometrial tonus did not change significantly except with bupivacaine where an increase occurred (P less than 0.001). These data indicate that local anesthetic agents may lower gravid UBF by a direct vascular effect and by stimulation of myometrial contractility. The possible clinical implications of these observations are discussed.

Anesthetics, Local↗
PubMed1986

Effect of selective occlusion of the umbilical arteries and/or veins on uterine blood flow in sheep.

Maternal uterine blood flow was depressed during total umbilical cord occlusion, probably based on an increased fetal cotyledonary tissue pressure (Hasaart and de Haan (1985) Eur. J. Obstet. Gynec. Reprod. Biol., 19, 125-131). This supposed mechanism was further analysed by performing selective occlusions of the umbilical arteries and/or veins (mean occlusion time 35 s). An occluding device which allowed separate occlusion of umbilical veins and arteries was applied to the umbilical cord in 7 chronically prepared fetal lambs between 106 and 135 days gestation. Median uterine artery blood flow (UBF) was measured with an electromagnetic flow meter. During occlusion of both umbilical veins (VV, n = 22) in 6 animals a maximal decrease in UBF to 87.5% of control value (P less than 0.001) was found at the end occlusion, followed by a gradual return to control value in the post occlusion period. Occlusion of both umbilical arteries (AA, n = 29) in 5 animals was accompanied by a slight increase in UBF to 103% of control value (P less than 0.01). Total occlusion of the umbilical arteries and veins simultaneously (n = 17) in 4 animals did not result in any change in UBF. The changes in volume and turgor in the fetal cotyledonary tissue associated with the arterial and venous occlusions should lead to respectively a decrease (AA) and increase (VV) in resistance to maternal flow, causing the changes in uterine blood flow. It is concluded that volume changes in the fetal compartment of the sheep placenta affect maternal uterine blood flow.

Animals↗
PubMed1980

Vascular and uterine responses to dobutamine and dopamine in the gravid ewe.

Dopamine, a naturally occurring catecholamine precursor of norepinephrine, has been used in the treatment of cardiogenic shock. Following intravenous administation it increases cardiac output, blood pressure, and renal blood flow. Dobutamine is a directly acting inotropic agent which increases myocardial contractility without significantly changing blood pressure. This study was devised to compare the effects of these two drugs on uterine blood flow (UBF), uterine tonus (UT), mean arterial blood pressure (MAP), and heart rate (HR). Chronically instrumented pregnant ewes near term were infused with differet concentrations of dopamine and dobutamine while HR, MAP, UT and UBF were recorded continuously. Dopamine produced a decrease in UBF and an increase in MAP and UT while the HR response was variable. Dobutamine administration resulted in a marked increase in HR and a decrease in UBF, while MAP and UT remained essentially unchanged. Uterine vascular resistance increased with both drugs during high-dosage administration, but the rise was more pronounced following dopamine infusion. Since dobutamine exhibits less alpha-adrenergic activity than dopamine this drug would seem to be preferred when an inotropic agent is required for treatment of the pregnant patient.

Animals↗
PubMed1977

Uterine blood flow and its distribution after chronic estrogen and progesterone administration.

The rates and distributions of uterine blood flow (UBF) were measured in conscious castrated ewes during estradiol, progesterone, and combined-hormone regimens. Supplemental progesterone decreased the magnitude of UBF observed on estradiol alone. Progesterone favored distribution of UBF to the uterine caruncles and estradiol favored distribution to the myometrium and uterine cervix. Proportionate endometrial blood flows were similar on all hormone regimens. These observations suggest that estradiol secretion may not be responsible for the definitive increase in UBF observed during ovine pregnancy.

Animals↗
PubMed1983

Relation between umbilical prostacyclin production and blood-flow in the fetus.

Umbilical blood-flow (UBF) was measured by ultrasonography in 28 pregnant women. A superfusion preparation was used to investigate the production of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), a breakdown product of prostacyclin (PGI2) and thromboxane B2 (TxB2), a breakdown product of TxA2, by specimens from the umbilical arteries of the infants born to these 28 mothers and those born to 36 other women in whom UBF had not been measured. UBF was significantly related to 6-keto-PGF1 alpha production. 6-keto-PGF1 alpha production was lower in infants of the 8 pre-eclamptic mothers (14.5 ng min-1 g-1) than in those of 45 healthy mothers (26.9 ng min-1 g-1). Generation of TxA2 by the umbilical artery was 15-25 times less than that of 6-keto-PGF1 alpha, and TxA2 concentrations were unrelated to UBF or the type of pregnancy. These data provide the first evidence for a direct association between blood-flow and PGI2 generation in human vasculature.

6-Ketoprostaglandin F1 alpha↗
PubMed2000

RNA polymerase I transcription in confluent cells: Rb downregulates rDNA transcription during confluence-induced cell cycle arrest.

When 3T6 cells are confluent, they withdraw from the cell cycle. Concomitant with cell cycle arrest a significant reduction in RNA polymerase I transcription (80% decrease at 100% confluence) is observed. In the present study, we examined mechanism(s) through which transcription of the ribosomal genes is coupled to cell cycle arrest induced by cell density. Interestingly with an increase in cell density (from 3 - 43% confluence), a significant accumulation in the cellular content of hyperphosphorylated Rb was observed. As cell density increased further, the hypophosphorylated form of Rb became predominant and accumulated in the nucleoli. Co-immunoprecipitation experiments demonstrated there was also a significant rise in the amount of hypophosphorylated Rb associated with the rDNA transcription factor UBF. This increased interaction between Rb and UBF correlated with the reduced rate of rDNA transcription. Furthermore, overexpression of recombinant Rb inhibited UBF-dependent activation of transcription from a cotransfected rDNA reporter in either confluent or exponential cells. The amounts or activities of the rDNA transcription components we examined did not significantly change with cell cycle arrest. Although the content of PAF53, a polymerase associated factor, was altered marginally (decreased 38%), the time course and magnitude of the decrease did not correlate with the reduced rate of rDNA transcription. The results presented support a model wherein regulation of the binding of UBF to Rb and, perhaps the cellular content of PAF53, are components of the mechanism through which cell cycle and rDNA transcription are linked. Oncogene (2000) 19, 3487 - 3497

Animals↗
PubMed2006

Human tumor suppressor p14ARF negatively regulates rRNA transcription and inhibits UBF1 transcription factor phosphorylation.

The nucleolar Arf protein has been shown to regulate cell cycle through both p53-dependent and -independent pathways. In addition to the well-characterized Arf-mdm2-p53 pathway, several partners of Arf have recently been described that could participate in alternative regulation process. Among those is the nucleolar protein B23/NPM, involved in the sequential maturation of rRNA. p19ARF can interact with B23/NPM in high molecular complexes and partially inhibit the cleavage of the 32S rRNA, whereas the human p14ARF protein has been shown to participate in the degradation of NPM/B23 by the proteasome. These data led to define Arf as a negative regulator of ribosomal RNA maturation. Our recent finding that the human p14ARF protein was able to specifically interact with the rRNA promoter in a p53-independent context, led us to analyse in vitro and in vivo the consequences of this interaction. Luciferase assay and pulse-chase experiments demonstrated that the rRNA transcription was strongly reduced upon p14ARF overexpression. Investigations on potential interactions between p14ARF and the transcription machinery proteins demonstrated that the upstream binding factor (UBF), required for the initiation of the transcriptional complex, was a new partner of the p14ARF protein. We next examined the phosphorylation status of UBF as UBF phosphorylation is required to recruit on the promoter factors involved in the transcriptional complex. Upon p14ARF overexpression, UBF was found hypophosphorylated, thus unable to efficiently recruit the transcription complex. Taken together, these data define a new p53-independent pathway that could regulate cell cycle through the negative control of rRNA transcription.

Animals↗
PubMed2006

A role for upstream binding factor in organizing ribosomal gene chromatin.

Human ribosomal genes are located in NORs (nucleolar organizer regions) on the short arms of acrocentric chromosomes. During metaphase, previously active NORs appear as prominent chromosomal features termed secondary constrictions, which are achromatic in chromosome banding and positive in silver staining. The architectural RNA polymerase I transcription factor UBF (upstream binding factor) binds extensively across the ribosomal gene repeat throughout the cell cycle. Evidence that UBF underpins NOR structure is provided by an examination of cell lines in which large arrays of a heterologous UBF binding sequences are integrated at ectopic sites on human chromosomes. These arrays efficiently recruit UBF even to sites outside the nucleolus, and during metaphase form novel silver-stainable secondary constrictions, termed pseudo-NORs, that are morphologically similar to NORs.

Binding Sites↗
PubMed2002

Fetal umbilical vascular response to chronic reductions in uteroplacental blood flow in late-term sheep.

OBJECTIVE: The present study was designed to determine the effects of chronic reduction in uterine blood flow (UBF) on umbilical blood flow (UmbBF) and fetal cardiovascular hemodynamics and oxygenation. STUDY DESIGN: Sixteen sheep with singleton pregnancies were instrumented on gestational day (GD) 110; an externally adjustable vascular occluder was placed on the common internal iliac artery. UBF in control animals rose from 867 +/- 61 mL/min on GD 115 to 1520 +/- 158 mL/min (n = 8) on GD 138, whereas UBF in restricted animals was maintained at 750 +/- 50 mL/min (n = 8). RESULTS: UmbBF in control animals increased from 472 +/- 25 mL/min to 744 +/- 58 mL/min over the study period from GD 115 to GD 138. This was associated with normal gestational increases in fetal arterial pressure and significant reductions in calculated umbilical vascular resistance. Although restricted animals initially had a similar UmbBF on GD 115, UmbBF rose only to 545 +/- 43 mL/min over the study period (control vs restricted, P <.008). Although fetal arterial pressure showed normal gestational changes, umbilical vascular resistance failed to decrease over gestation in restricted animals as it did in control animals. Fetal heart rate and oxygenation showed normal changes in both groups. CONCLUSION: Chronic reduction in UBF prevents umbilical vascular resistance from undergoing normal gestational decreases, leading to significantly lower UmbBF. This altered umbilical perfusion pattern would be expected to significantly affect fetal delivery of oxygen and nutrients and ultimately fetal growth.

Animals↗
PubMed1993

Coordinated decreases in rRNA gene transcription factors and rRNA synthesis during muscle cell differentiation.

rRNA synthesis decreases significantly during the differentiation of rat L6 myoblasts to myotubes. Nuclear run-on assays demonstrated that the decrease was attributable to decreased rates of rRNA gene transcription. Immunoblot analysis indicated a marked reduction in amounts of the RNA polymerase I transcription factors UBF1 and UBF2 (upstream binding factors 1 and 2, respectively). The levels of these factors dropped in parallel with the down-shift in rRNA gene transcription. The amount of UBF does not fall due to a general decrease in cellular protein, as myosin heavy-chain protein accumulates markedly during this same time. RNA blots of total RNA isolated from myoblasts and differentiating myotubes showed a decrease in the mRNA for UBF, at the same time the mRNA for myogenin was accumulating. The down-shift in UBF mRNA levels preceded the decrease in the protein levels for UBF. There have been reports that the acute response of the rRNA gene transcription system to physiological signals in many systems involves an RNA polymerase I-associated factor. However, our results imply that the regulation of rRNA gene DNA transcription in response to physiological processes, such as differentiation, may involve multiple regulatory pathways.

Adenosine Triphosphate↗
PubMed1995

Angiotensin II-induced hypertrophy of rat vascular smooth muscle is associated with increased 18 S rRNA synthesis and phosphorylation of the rRNA transcription factor, upstream binding factor.

Hypertrophy of vascular smooth muscle cells (VSMC) is an important adaptive response of hypertension. Drug intervention studies have implicated a role for angiotensin II (A-II) in the mediation of VSMC hypertrophy in vivo, and A-II is a potent hypertrophic agent for VSMC in culture. Our laboratory has previously shown that A-II-induced hypertrophy of cultured VSMC is due in part to generalized increases in protein synthesis and increased content of rRNA. The aim of the present study was to determine if A-II stimulates rRNA gene synthesis and whether the rRNA transcription factor, upstream binding factor (UBF), is involved. Nuclear run-on analysis demonstrated that A-II induced a greater than 5-fold increase in rRNA gene synthesis within 6 h of stimulation. A-II also stimulated a rapid increase in UBF phosphorylation as well as nucleolar localization, but no changes in the content of UBF. Phosphoamino acid analysis showed that phosphorylation occurred only on serine residue(s). Results demonstrate that increased transcription of ribosomal DNA contributes to the A-II-induced increase in protein synthesis and VSMC hypertrophy, and suggest that an important regulatory event in this pathway may be the phosphorylation and/or nucleolar localization of UBF.

Angiotensin II↗