Randomised trial comparing the upright and supine positions for the second stage of labour

OBJECTIVE: To assess the maternal and neonatal effects of upright compared with recumbent positions during delivery, in terms of defined outcome variables. DESIGN: A randomised controlled trial. SETTING: St Monica's Nursing Home, a midwife based maternity unit in Cape Town, South Africa. PARTICIPANTS: Five hundred and seventeen women of low obstetrical risk assigned to deliver at the nursing home. RESULTS: The trial showed that women who adopted the upright posture for delivery experienced less pain. perineal trauma and fewer episiotomies than those who delivered in the supine position. CONCLUSION: The data suggest that in women of low obstetrical risk, choice of posture during delivery may be encouraged.     

Stroke volume measurement during supine and upright cycle exercise by impedance cardiography

This study evaluated impedance cardiography (ZCG) estimates of stroke volume (SV) during exercise. Seven subjects were studied at rest and during progressive cycle exercise in supine and upright positions. SV was determined by ZCG (SVZCG) during exercise and for the first 5 cardiac cycles following exercise. SVZCG was compared with separate measurements of SV by CO2 rebreathing (SVCO2). Static blood resistivity (p) was measured at each level of exercise. No significant differences were found between supine exercise and immediate post-exercise values for the peak of the first derivative of the impedance change (dZ/dtmax), left ventricular ejection time (LVET), or SVZCG. Small differences in dZ/dtmax and SVZCG, but not LVET, were found in exercise to post-exercise cycling in the upright position. Intra-individual SVZCG and SVCO2 were moderately correlated (upright mean r = 0.64, supine r = 0.42) from rest to 70% of peak VO2. Similar correlations were found between Pulse-O2 (VO2/heart rate, used as an index to SV) and both SVZCG (upright r = 0.73, supine r = 0.57) and SVCO2 (upright r = 0.8, supine r = 0.65). The ZCG parameters dZ/dtmax and LVET correlated better with Pulse-O2 (dZ/dtmax: upright r = 0.92, supine r = 0.73; LVET: upright r = -0.9, supine r = -0.9). SVZCG calculated with the Kubicek equation performed as well as SVCO2. ZCG might be a superior method if the inversely correlated parameters, dZ/dtmax and LVET, were not expressed as a product to calculate SV.     

Alveolar oxygen uptake and femoral artery blood flow dynamics in upright and supine leg exercise in humans

We tested the hypothesis that the slower increase in alveolar oxygen uptake (VO2) at the onset of supine, compared with upright, exercise would be accompanied by a slower rate of increase in leg blood flow (LBF). Seven healthy subjects performed transitions from rest to 40-W knee extension exercise in the upright and supine positions. LBF was measured continuously with pulsed and echo Doppler methods, and VO2 was measured breath by breath at the mouth. At rest, a smaller diameter of the femoral artery in the supine position (P < 0. 05) was compensated by a greater mean blood flow velocity (MBV) (P < 0.05) so that LBF was not different in the two positions. At the end of 6 min of exercise, femoral artery diameter was larger in the upright position and there were no differences in VO2, MBV, or LBF between upright and supine positions. The rates of increase of VO2 and LBF in the transition between rest and 40 W exercise, as evaluated by the mean response time (time to 63% of the increase), were slower in the supine [VO2 = 39.7 +/- 3.8 (SE) s, LBF = 27.6 +/- 3.9 s] than in the upright positions (VO2 = 29.3 +/- 3.0 s, LBF = 17.3 +/- 4.0 s; P < 0.05). These data support our hypothesis that slower increases in alveolar VO2 at the onset of exercise in the supine position are accompanied by a slower increase in LBF.     

Effect of angiotensin converting enzyme (ACE) and angiotensins on human sperm functions

The presence of components of the renin angiotensin system (RAS) and specific receptors of angiotensin II in the female and male reproductive tract supports the hypothesis that reproductive functions may be controlled by RAS. Therefore, the present study investigated the influence of ACE and angiotensins on sperm functions and the sperm-egg interaction. The experiments did not indicate direct effects of ACE on the capacitation process or acrosome reaction. Release of ACE from human spermatozoa during capacitation was not related to their ability to undergo acrosome reaction after stimulation with ionophore. Therefore, ACE release does not seem to be a useful clinical marker for human sperm capacitation. However, decreased binding of human spermatozoa to the oolemma of zonafree hamster oocytes after inhibition of ACE by captopril indicates that kininase II is involved in sperm-egg interactions. In contrast to other studies, incubation with captopril had no influence on sperm binding to the zona pellucida. Because effects of ACE on sperm-egg interactions but not on capacitation or acrosome reaction were observed, several experiments were performed to study the influence of substrates and products on the acrosome reaction. Angiotensin II induced the acrosome reaction dose-dependently, whereas angiotensin I had no effect on the acrosome reaction. The effect of angiotensin II on acrosome reaction seems to be calcium-dependent and mediated by protein kinases. Since a specific type 2 angiotensin II receptor inhibits the acrosome reaction induced by angiotensin II, this subtype of receptors may be present at the surface of sperm heads. Another clue for the presence of type 2 receptors on human spermatozoa is the finding that pertussis toxin did not inhibit the angiotensin II induced acrosome reaction. In contrast to type 1 angiotensin II receptors, type 2 receptors are known to be G-protein independent.     

Perception of the upright in normal and schizophrenic subjects

To see the effects of a large angle of frame-tilt, movement of the rod in the clockwise direction, and the difference between the normal and schizophrenic subjects in the perception of the upright, a mixed design (subjects X angle X presentation X trial) was used. 24 normal and 24 schizophrenic subjects were tested in a darkroom with a rod-and-frame test. The results showed a small error with a clockwise movement of the rod, when the frame also was tilted clockwise, and no difference in perception of the upright between the normal and schizophrenic subjects.     

Regional sympathetic nervous activity and oxygen consumption in obese normotensive human subjects

BACKGROUND: Disturbed sympathetic nervous function may be of importance in obesity; sympathetic underactivity could contribute to deficient thermogenesis, positive energy balance, and weight gain, while in contrast, sympathetic nervous overactivity would predispose to the development of obesity-related hypertension. Global indices of sympathetic nervous system (SNS) function such as plasma or urinary norepinephrine (NE) have been unable to define SNS status in obesity. Since regional SNS activity can be altered in the absence of global changes, we investigated SNS activity in the heart, kidneys, and hepatomesenteric bed in healthy human subjects across a wide body mass index (BMI) range of between 19.6 and 35.5. METHODS AND RESULTS: Whole-body and regional plasma NE kinetics using [3H]-labeled NE were assessed. Regional oxygen consumption was measured by combining arteriovenous differences in oxygen content and regional blood flow. Arterial plasma NE and whole-body plasma NE spillover were unrelated to BMI. With a BMI cutoff of 27, mean cardiac NE spillover was 46% lower in the obese subjects when compared with the lean subjects (P=.017). Renal NE spillover was significantly correlated with BMI (r=.668, P=.001), the mean value in the obese subjects being more than twice that in the lean subjects. Hepatomesenteric NE spillover was comparable in lean and obese subjects. Renal and hepatomesenteric oxygen consumption were both significantly higher in the obese subjects compared with lean subjects. CONCLUSIONS: Regional SNS activity is heterogeneous in the obese state. Important regional alterations, which may be clinically relevant, occur in the absence of changes in global indices of sympathetic nervous function. The enhanced renal NE spillover in obesity may have implications for the development of hypertension in this group, whereas the low cardiac sympathetic tone would be expected to be cardioprotective. Enhanced visceral oxygen consumption evident in the kidneys and hepatomesenteric circulation in proportion to body mass contributes to the greater resting oxygen consumption in obesity.     

Mechanical properties of human saphenous veins from normotensive and hypertensive patients

The three-dimensional structure of a synthetic peptide corresponding to the putative transmembrane segment M3 (amino acid residues 277-301) of the alpha subunit of the nicotinic acetylcholine receptor from Torpedo californica has been studied by means of two-dimensional 1H-NMR spectroscopy in a chloroform/methanol (1:1) mixture containing 0.1 M LiClO4. Complete resonance assignment has been performed using double-quantum-filtered COSY (DQF-COSY), TOCSY and NOESY spectra. The spatial structure has been calculated using the Diana program on the basis of integrated intensities of NOESY spectra. HN-C(alpha)H and HC(alpha)-C(beta)H spin-spin coupling constants. Residues 279-297 of M3 form a right-handed helix (root mean square deviation is 0.032 nm for backbone atoms and 0.088 nm for all heavy atoms). The conformations of the 17 side chains have been unambiguously determined. The obtained structure is in accord with the photolabeling pattern of the membrane nicotinic acetylcholine receptor (nAChR) which suggests alpha-helical structure of M3 in the labeled portion [Blanton, M. P. & Cohen, J. B. (1994) Biochemistry 33, 2859-2872].     

Metabolic deesterification of tazarotene in human blood and rat and human liver microsomes

Tazarotene is a novel acetylenic retinoid for the treatment of psoriasis and acne. We examined (1) the hydrolysis of tazarotene in blood from Japanese-American and Caucasian subjects, (2) the esterases responsible for this hydrolysis in human blood, and (3) tazarotene hydrolysis in rat and human liver microsomes. Tazarotene hydrolysis and enzyme inhibition were assessed by monitoring the disappearance of tazarotene and the appearance of its primary metabolite tazarotenic acid by HPLC. In blood, tazarotene was converted mainly to tazarotenic acid via first-order kinetics, and there was no statistically significant difference in the hydrolytic (metabolic) rate of tazarotene in uninhibited Japanese-American and Caucasian blood. Physostigmine (a cholinesterase inhibitor), bis(p-nitrophenyl) phosphate (a carboxylesterase inhibitor), and EDTA (an aromatic esterase inhibitor) did not significantly affect tazarotene hydrolysis in blood. Paraoxon, an inhibitor of all serine esterases including cholinesterase and carboxylesterase, decreased the hydrolysis of tazarotene to tazarotenic acid by 95% in both blood and liver microsomes. In conclusion, blood and liver esterases play a significant role in the hydrolysis of tazarotene to tazarotenic acid, and paraoxon-inhibitable forms of esterases are involved in this hydrolysis in humans.     

Heart and red blood cell antioxidant status and plasma lipid levels in the spontaneously hypertensive and normotensive Wistar-Kyoto rat

Heart and red blood cell endogenous antioxidant status and plasma lipids were investigated in hypertensive, 14-week-old spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats fed a standard commercial rat chow. Specific heart and red blood cell antioxidant enzyme activities, as well as the susceptibility of tissues to H2O2-induced glutathione (GSH) depletion and lipid peroxidation, were measured. Systolic blood pressure in SHR was greater than in WKY rats at 13 weeks of age (197 +/- 12 vs. 132 +/- 14 mmHg (1 mmHg = 133.3 Pa); p < or = 0.05), confirming the presence of hypertension in SHR. Red blood cell catalase (CAT) and superoxide dismutase (SOD) activities were greater (p < or = 0.05) in SHR than WKY rats. Red blood cell CAT activity was positively correlated (r = +0.634; p = 0.026) with SOD, which in turn was correlated (r = +0.709; p = 0.049) with systolic blood pressure. Heart SOD activity was higher (p < or = 0.05) in SHR, while glutathione reductase (GSSG-Red) activity was lower (p < or = 0.05) than in WKY rats. This reduced ability to recycle GSH in the heart coincided with greater (p < or = 0.05) levels of H2O2-induced lipid oxidation products in SHR. Plasma total cholesterol and triacylglycerol levels were lower (p < or = 0.05) in SHR than WKY rats, with no visible signs of atherosclerosis in either SHR or WKY rats. In summary, hypertension in SHR was associated with alterations in antioxidant enzyme profiles of red blood cells and heart, with the latter showing an increased susceptibility to in vitro lipid oxidation. Although hypertension is a recognized factor in the development of human atherosclerosis, spontaneously hypertensive rats did not exhibit signs of aortic plaque, reflecting the resistance of this species to the development of atherosclerosis.     

Circulating plasma prekallikrein and tissue kallikrein in normotensive and hypertensive humans: effects of angiotensin II infusion

Kinins lower blood pressure but the stimuli leading to kinin generation and their origin are less well known. We administered angiotensin II in graded infusion doses to patients with primary hypertension and normotensive controls to study the effects of on circulating kallikreins. Angiotensin II infusion did not significantly alter plasma prekallikrein or tissue kallikrein levels and the plasma levels and their changes did not correlate with blood pressure levels or changes. In the normotensive group prekallikrein levels and renin activity correlated negatively with urinary sodium and chloride excretion during basal conditions and partially during the infusion. U-tissue kallikrein concentration increased in the normotensive group. Thus, acute elevation of blood pressure induced by angiotensin II does not activate the circulating kallikrein-kinin systems. Data rather indicate that the circulating kallikrein-kinin systems may be related to alterations in volume and sodium balance and that these mechanisms may be altered in primary hypertension.     

Metabolic activation and carcinogen-DNA adduct detection in human larynx

Putative carcinogen-DNA adducts in human larynx tissues (n = 25) from smoker and non/ex-smoker patients were examined by 32P-postlabeling and compared with the metabolic activation capacity of larynx microsomes and cytosols from the same tissues. Hydrophobic DNA adducts were evident only in smokers, and chromatographic profiles of the adducts were similar using either the butanol extraction or nuclease P1 enhancement method, which suggested that the adducts may be derived from polycyclic aromatic hydrocarbons but not aromatic amines. Immunoblots of larynx microsomes using anti-cytochrome P450 1A1/1A2, 2C, 3A4, 2E1, and 2A6 antibodies showed intensities ranging from 1-10% of that typically observed with human liver microsomes. Enzymatic assays of larynx microsomes showed appreciable activity for benzo(a)pyrene hydroxylation (P450 1A1 and 2C) but not for 4-aminobiphenyl N-oxidation (P450 1A2), which indicated that the observed immunoreactivity was for P450 1A1; this represents the highest level of this P450 yet detected in human extrahepatic tissues. Accordingly, total DNA adduct levels in the larynx correlated strongly with levels of P450 2C, 1A1, and 3A4 but not with P450 2E1 or 2A6. Larynx cytosols also showed appreciable aromatic amine N-acetyl-transferase activity for p-aminobenzoic acid (NAT-1) but not for sulfamethazine (NAT-2); however, NAT-1 activity was not correlated with total DNA adducts, which is again consistent with the lack of aromatic amine-DNA adducts detected by 32P-postlabeling. Thus, these results suggest that the DNA adducts detected in human larynx are largely derived from metabolic activation of polycyclic aromatic hydrocarbons in cigarette smoke by P450 2C, 3A4, and/or 1A1.     

Visual dependency in the erect and supine positions.

Examined the field dependency-independency of 37 Ss under supine and erect body position. Females were more field dependent than males. No significant differences were found between male pilots and nonpilots. Males exhibited greater field dependency in the supine position. Results suggest the need to consider 3 separate measures of field dependency-slope, breakpoint, and variability. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tubular fluid concentrations and kidney contents of angiotensins I and II in anesthetized rats

Previous micropuncture studies have reported nanomolar concentrations of angiotensin II in proximal tubular fluid and have indicated that angiotensin II or a precursor may be secreted into the tubular lumen. Further experiments were performed to determine if proximal tubular fluid angiotensin I concentrations are also greater than plasma and kidney levels and to estimate the degree of intrarenal compartmentalization of the angiotensin peptides. Free-flow proximal tubular fluid samples were collected in micropipets and were pooled for each animal. At the end of each experiment, a blood sample was collected and the micropunctured left kidney was harvested and homogenized in methanol. The angiotensin I concentration in proximal tubular fluid samples averaged 6.1 +/- 1.2 pmol/mL, whereas the angiotensin II concentration averaged 8.1 +/- 1.6 pmol/mL (N = 13). HPLC analysis of a separate sample pooled from collections in five rats indicated that the immunoreactive angiotensin I and angiotensin II primarily represented authentic angiotensin I and II. Plasma concentrations of angiotensin I and angiotensin II averaged 0.39 +/- 0.09 and 0.15 +/- 0.03 pmol/mL, respectively. The kidney contents of angiotensin I and angiotensin II were 1.28 +/- 0.24 and 0.97 +/- 0.17 pmol/g of kidney, respectively. These findings indicate that proximal tubular fluid contains nanomolar concentrations of angiotensin I as well as angiotensin II. These high tubular fluid concentrations, which greatly exceed the plasma and kidney levels, likely reflect net secretion of the angiotensin peptides by proximal tubule cells.(ABSTRACT TRUNCATED AT 250 WORDS)     

Determinants of plasma levels of plasminogen activator inhibitor-1 : A study of normotensive twins

We investigated whether plasma levels of the plasminogen activator inhibitor type 1 antigen (PAI-1:Ag) are genetically determined in monozygotic (MZ) and dizygotic (DZ) twins. Twenty-five pairs of healthy twins underwent measurements of PAI-1:Ag and other variables, including body mass index, mean blood pressure, plasma renin activity, insulin, and glucose. To ascertain the zygosity of twins, highly discriminating micro- and minisatellite systems with variable numbers of tandem repeats were analyzed by PCR amplification followed by polyacrylamide gel electrophoresis. Subjects were also genotyped for the 4G/5G polymorphism by PCR. Estimates of genetic variance and heritability were obtained for PAI-1:Ag, and for body mass index, mean blood pressure, plasma renin activity, glucose, and insulin by jointly examining data in a path analysis with TWINAN90. Results showed that 12 pairs of twins were MZ and 13 were DZ. All tests of genetic variance [within pair (WP): F=6.24, P=0.002; among component (AC): F=2.62, P=0.04; average absolute difference t test=3. 00, P=0.004] showed significant genetic variance of PAI-1:Ag, but not of the other variables. Three tests of heritability (WP=0.837, P=0.002; AC=1.791, P<0.05; intraclass correlation: 1.180, P=0.001) consistently showed significant PAI-1:Ag heritability. Additive genetic influences (A), dominance genetic effect (D), and random environmental influences (E) accounted for 0.714, 0.154, and 0.132 of PAI-1:Ag variance, respectively. No effect of different 4G/5G genotypes was found. Thus, these results show significant genetic variance and heritability of PAI-1:Ag and suggest that A is more important than both D and E in determining PAI-1:Ag variance.     

Modeling and prediction of human behavior

We propose that many human behaviors can be accurately described as a set of dynamic modes (e.g., Kalman filters) sequenced together by a Markov chain. We then use these dynamic Markov models to recognize human behaviors from sensory data and to predict human behaviors over a few seconds time. To test the power of this modeling approach, we report an experiment in which we were able to achieve 95% accuracy at predicting automobile drivers' subsequent actions from their initial preparatory movements.