bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lack of Antagonism in the Antihypertensive Effects of Clonidine and Prazosin in Man
Authors: Andréjak M. , Fievet P. , Makdassi R. , Comoy E. , De Fremont J. F. , Coevoet B. , Fournier A. 
Published: August 2015

1. In four patients, whose hypertension was not controlled (supine blood pressure &gt; 150–90 mmHg) by addition of 5 mg/day of prazosin to previous treatment (diuretics and β-blockers), clonidine (150–450 μg/day) led to control of hypertension in three cases.
2. In ten patients whose hypertension was not controlled by a treatment including clonidine (300–450 μg/day), the progressive addition of prazosin to a maximal dose of 4–22.5 mg/day led to control of hypertension in nine cases (mean supine blood pressure decreased from 174–102 to 144–88 mmHg).
3. In 13 hospitalized patients, clonidine was abruptly interrupted whereas prazosin was continued. Mean blood pressure (± sem) rose from 145 ± 1/85 ± 2 to 169 ± 7/104 ± 5 mmHg 48 h after clonidine withdrawal whereas plasma noradrenaline and adrenaline rose from 328 to 758 pg/ml and from 75 to 137 pg/ml. No subjective symptoms were noted. There was a negative correlation between blood pressure increase and the dose of prazosin.
4. It is concluded that (a) there is no antagonism between clonidine and prazosin in their antihypertensive action in man when used at usual clinical doses, (b) a protective effect of prazosin against an eventual clonidine withdrawal syndrome is suggested by the negative correlation between blood pressure increase and the dose of prazosin.
Body-Fluid Composition in Normal and Hypertensive Man
Authors: Bauer J. H. , Brooks C. S. 
Published: August 2015

1. Erythrocyte mass, plasma volume (PV), extracellular fluid volume (ECFV) and total body water were simultaneously measured in 30 normotensive and 30 normal-renin hypertensive Caucasian male subjects for accurate determination of the presence or absence of a disorder(s) in body-fluid composition in hypertension.
2. The results indicate that plasma volume and total blood volume are lower in hypertensive subjects than in normotensive control subjects. The PV comprised 19% of the ECFV in both control and hypertensive subjects.
3. ECFV was lower in hypertensive subjects than in normotensive control subjects; the PV and interstitial fluid components of the ECFV were reduced by similar proportions. The ECFV, furthermore, comprised a smaller portion of the total body water in hypertensive subjects than that in control subjects.
4. We conclude that in the hypertensive state there is a reduction in the ECFV, but that there is no change in the partition of the ECFV between the plasma and interstitial components.
Functional Interaction between Angiotensin and Sympathetic Reflexes in Cats
Authors: Hatton R. , Clough D. P. , Adigun S. A. , Conway J. 
Published: August 2015

1. Lower-body negative pressure (LBNP) was used to stimulate sympathetic reflexes in anaesthetized cats. At −50 mmHg for 10 min it caused transient reduction in central venous pressure and systemic arterial blood pressure. Arterial blood pressure was then restored within 30 s and there was a tachycardia. Central venous pressure showed only partial recovery. The resting level of plasma renin activity (PRA; 2.9–3.2 ng h−1 ml−1) did not change until approximately 5 min into the manoeuvre.
2. When converting-enzyme inhibitor (CEI) was given 75 s after the onset of suction it caused a greater and more sustained fall in arterial blood pressure than when administered alone. The angiotensin II (ANG II) antagonist [Sar1,Ala8]ANG II produced similar effects after a short-lived pressor response.
3. This prolonged fall in arterial blood pressure produced by CEI was not associated with reduced sympathetic efferent nerve activity. This indicates that the inhibitor affects one of the peripheral actions of angiotensin and in so doing produces vasodilatation of neurogenic origin.
4. These findings suggest that angiotensin, at a level which does not exert a direct vasoconstrictor action, interacts with the sympathetic nervous system to maintain arterial blood pressure when homeostatic reflexes are activated. A reduction in the efficiency of these reflexes by CEI may contribute to its hypotensive effect.
The Effect of Knee Injury on the Number of Muscle Fibres in the Human Quadriceps Femoris
Authors: Young A. , Hughes I. , Round J. M. , Edwards R. H. T. 
Published: August 2015

1. By means of ultrasound scanning, bilateral measurements of the cross-sectional area of the quadriceps muscle group were made in 14 young adults with unilateral thigh muscle wasting after knee injury. Needle biopsy specimens from the lateral mass of the muscle were used to estimate the myofibre cross-sectional area for both quadriceps of each subject.
2. The cross-sectional area of the quadriceps of each patient's injured limb was always smaller than that of the contralateral muscle. The wasting was largely localized to the quadriceps, with relative sparing of the other thigh muscles.
3. None of the biopsies showed any abnormality apart from a reduction in fibre size. In each case, the injured limb's reduced quadriceps cross-sectional area was associated with a reduced mean fibre area.
4. The ratio of the cross-sectional area of a muscle to its mean fibre area is a function of the number of fibres it contains. The ratio varied considerably from patient to patient but there was close agreement between the values obtained for the two limbs of each patient.
5. The quadriceps wasting produced by knee injury was due to muscle fibre atrophy. There was no evidence for a change in the number of fibres in the muscle.
Intravenous Infusion of α-Oxoisocaproate: Influence on Amino Acid and Nitrogen Metabolism in Patients with Liver Cirrhosis
Authors: Eriksson L. S. , Hagenfeldt L. , Wahren J. 
Published: August 2015

1. The metabolic effect of α-oxoisocaproate (4-methyl-2-oxovalerate) infusion was examined in six patients with cirrhosis and in nine healthy control subjects. The arterial concentrations of amino acids, urea, ammonia, insulin and catecholamines were determined in the basal state and during intravenous infusion of α-oxoisocaproate (300 μmol/min) for 150 min. The exchanges of amino acids and substrates across the splanchnic region, the brain and the leg were examined in the healthy subjects by a catheter technique.
2. Basal α-oxoisocaproate levels were similar in patients and control subjects. During infusion the concentrations of α-oxoisocaproate rose to 90–130 μmol/l; they were 20–35% lower in the patients. Arterial leucine concentration increased in both groups to 250–300 μmol/l. Valine and isoleucine concentrations decreased (50–60%) as did to a lesser extent the concentrations of aromatic amino acids and methionine.
3. Regional exchange of amino acids was not significantly influenced by α-oxoisocaproate infusion. Arterial urea concentration decreased (12%, P &lt; 0.05) and ammonia levels rose (15–25%, P &lt; 0.05) in both groups. In the patients both adrenaline (100%, P &lt; 0.001) and noradrenaline concentrations were elevated (350%, P &lt; 0.001) in the basal state; insulin levels were similar to those in control subjects.
4. It is concluded that α-oxoisocaproate is rapidly transaminated to leucine in patients with cirrhosis and in healthy control subjects. α-Oxoisocaproate infusion resembles leucine infusion in its influence on aromatic amino acid concentrations, but in addition it elicits increased ammonia levels and decreased urea formation.
Indomethacin or Aprotinin Infusion: Effect on Reversal of Chronic Two-Kidney, One-Clip Hypertension in the Conscious Rat
Authors: Russell G. I. , Bing R. F. , Swales J. D. , Thurston H. 
Published: August 2015

1. Blood pressure was monitored continuously in conscious rats with chronic Goldblatt two-kidney, one-clip hypertension.
2. Hypertension was rapidly reversed by removal of the constricting clip and the reversal was complete by 12 h, although structural vascular changes persisted for much longer.
3. Blood pressure in this model of hypertension was not affected by a 15 h infusion of either indomethacin or aprotinin.
4. The pattern of fall in blood pressure after removal of the clip was similar when animals were infused with either indomethacin or aprotinin. Blood pressure at 24 h was normal and did not differ significantly from that of unclipped rats given a glucose infusion.
5. The fall in blood pressure produced by unclipping therefore did not appear to be mediated via the prostaglandin or kallikrein systems.
Turnover Studies of Human β2-Microglobulin in the Rat: Evidence for a β2-Microglobulin-Binding Plasma Protein
Authors: Nguyen-Simonnet H. , Vincent C. , Gauthier C. , Revillard J. P. , Pellet M. V. 
Published: August 2015

1. 123I-labelled β2-microglobulin (β2m) was injected into rats and protein or non protein-bound radioactivity was determined in plasma urine and several organs.
2. The observed kinetics differed from those expected according to the bicompartmental model for plasma protein turnover. The difference was attributed to the binding of a part of the tracer to a plasma component. Chromatography of plasma taken after injection of β2m showed an additional peak of radioactivity at the 55 000–80 000 daltons position.
3. In animals with ligated renal arteries, disappearance of the tracer from the plasma was markedly prolonged, and little non-protein-bound radioactivity was detectable in plasma, indicating that the kidney was the major site of catabolism of β2m.
4. Chromatography of plasma from control rats and rats with ligated renal arteries showed that the kidney was the major site of catabolism for free β2m only.
5. In normal rats, the urine was found to contain only non-protein-bound radioactivity.
Evidence for a Lactate Transporter in the Plasma Membrane of the Rat Hepatocyte
Authors: Monson J. P. , Smith J. A. , Cohen R. D. , Iles R. A. 
Published: August 2015

1. The rate of uptake in 15 s of l- and d-lactate was studied in isolated hepatocyte preparations from starved rats.
2. Observations were also made of the effect of different concentrations of unlabelled l- and d-lactate on l-[14C]- and d-[14C]-lactate uptake.
3. Lactate uptake into hepatocytes appears to occur by two processes, one saturable and at least partially stereospecific, the other nonsaturable, at least up to 28 mmol/l, and probably representing simple non-carrier assisted diffusion.
4. The 15 s uptake of lactate is inhibited by α-cyano-3-hydroxycinnamate and by p-chloromercuriphenylsulphonate but not by the general anion transporter inhibitor 4-acetamido-4′-isothiocyanostilbene-2,2′-disulphonic acid, ouabain or the structural analogue dl-p-hydroxyphenyl-lactate.
5. Transporter-mediated lactate entry into liver cells is enhanced by lowered extracellular pH.
6. It is suggested that the contribution of the diffusion component of lactate entry into the cell may be exaggerated by the artifactual nature of the isolated hepatocyte preparation, and that, under some circumstances in vivo, lactate transport into hepatocytes could determine the rate of lactate removal from blood.
Sympathetic Reflex Control of Subcutaneous Blood Flow in Tetraplegic Man during Postural Changes
Authors: Skagen K. , Jensen K. , Henriksen O. , Knudsen L. 
Published: August 2015

1. The effect of head-up tilt upon subcutaneous blood flow in the distal arm and leg was studied in 12 patients with complete traumatic spinal cord transection at the cervical level.
2. Blood flow was measured by the local 133Xe washout technique.
3. Leg lowering induced a 47% decrease in blood flow in the distal leg. During head-up tilt (45°) blood flow in the leg decreased by 48%. In the arm remaining at heart level blood flow decreased by 37% during tilt and this vasoconstriction could be prevented by nervous blockade with lignocaine injected subcutaneously 5 cm proximally to the labelled area. Leg blood flow was unaltered by proximal blockade but could be blocked by local infiltration in the labelled area with lignocaine in low doses.
4. Head-up tilt of tetraplegic patients induced vasoconstriction in the subcutaneous tissue of the forearm, which could be prevented by proximal blockade. Thus the vasoconstriction could be due to a spinal sympathetic reflex mechanism. This as well as local mechanisms including the veno-arteriolar reflex may play a role in recovery of arterial blood pressure during head-up tilt in the tetraplegic patient.
Uptake of l-valyl-l-Valine and Glycylsarcosine by Hamster Jejunum in Vitro
Authors: Burston D. , Wapnir R. A. , Taylor E. , Matthews D. M. 
Published: August 2015

1. Preliminary observations concerned with the effect of the lipophilic properties of the amino acid side-chains of peptides on their apparent affinity for uptake by rings of everted hamster jejunum showed that of the series glycylglycine, l-alanyl-l-alanine, l-valyl-l-valine and l-leucyl-l-leucine, with increasingly lipophilic side-chains, l-valyl-l-valine, not l-leucyl-l-leucine, was the most powerful inhibitor of uptake of the hydrolysis-resistant dipeptide glycylsarcosine. This apparently anomalous observation indicated a need for further investigation, and this paper reports investigations of the kinetics of uptake of l-valyl-l-valine and of competition for uptake between l-valyl-l-valine and glycylsarcosine.
2. l-Valyl-l-valine was capable of complete competitive inhibition of mediated uptake of glycylsarcosine. Free l-valine did not inhibit mediated uptake of glycylsarcosine. Glycylsarcosine could inhibit mediated uptake of l-valyl-l-valine only partially, but a mixture of glycylsarcosine and l-valine was capable of producing complete inhibition of mediated uptake of l-valyl-l-valine.
3. Investigation of the kinetics of uptake of l-valyl-l-valine indicated two mediated components. Component (a), which disappeared in the presence of free l-leucine, probably represented uptake of free l-valine after hydrolysis of the peptide. Component (b) probably represented peptide uptake.
4. The estimates of Kt obtained for uptake of intact l-valyl-l-valine were many times greater than Ki for inhibition of uptake of glycylsarcosine by l-valyl-l-valine. A possible explanation of the discrepancy is the existence of two pathways for uptake of l-valyl-l-valine and glycylsarcosine, for one of which l-valyl-l-valine has a low Kt (i.e. a high affinity) not readily demonstrable by kinetic analysis.
5. The results suggest that mediated uptake of l-valyl-l-valine is the result of at least two processes, uptake of intact peptide by a mechanism or mechanisms shared with glycylsarcosine and also hydrolysis followed by uptake of free l-valine; estimates of the proportions of intact valine and of free valine taken up by mediated transport suggest that at pH 5 uptake of intact peptide varies from 25% at low concentrations to 55% at high concentrations. They do not explain why l-valyl-l-valine is a stronger inhibitor of uptake of glycylsarcosine than the more lipophilic l-leucyl-l-leucine, but do suggest how such a situation could arise.
Plasma Histamine and Catecholamines in Stable Asthmatic Subjects
Authors: Barnes P. J. , Ind P. W. , Brown M. J. 
Published: August 2015

1. Venous plasma histamine and catecholamines were measured in stable asthmatic subjects by a recently developed specific and sensitive radioenzymatic assay.
2. Plasma histamine concentrations were significantly elevated in both extrinsic and intrinsic asthmatic subjects, compared with both normal controls and patients with chronic obstructive airways disease. There was no correlation between histamine concentration and severity of airways obstruction, however.
3. Elevated plasma histamine concentrations at rest-5-indicate increased release of mediators from ‘leaky’ mast cells in asthma.
4. Plasma catecholamine concentrations in asthmatic subjects did not differ from normal and there was no correlation with severity of broncho- constriction or with plasma histamine concentration.
Set-Point Displacement for Behavioural Thermoregulation in Anorexia Nervosa
Authors: Luck P. , Wakeling A. 
Published: August 2015

1. The temperatures of thermal stimuli which evoked a feeling of maximal pleasantness upon contact with the hands of 14 malnourished patients with anorexia nervosa and 19 control subjects have been determined. A uniform skin temperature of 35°C for all individuals studied was achieved by immersion of the subjects and patients in water at that temperature. Core temperatures of the anorexic patients were similar to those of the control subjects, but six of the patients preferred temperatures that were significantly higher than those of the control subjects. The thermal preferences of the remainder of the patients were similar to those of the control subjects.
2. The abnormally high thermal preferences of some of the anorexic patients could not be attributed to abnormal thyroid status, since values for serum free thyroxine measured in this group were similar to those obtained for the remaining patients. The abnormal responses persisted after there had been a substantial gain in the patients'weight and did not therefore appear to be directly due to malnutrition.
3. Elevation of deep body temperature produced an expected shift in preference towards lower stimulus temperatures in a sample of subjects from the control group, and in the patients who had initially preferred temperatures within the range of the controls. In the patients who had initially preferred abnormally high stimulus temperatures, however, hyperthermia produced little change in thermal preference.
4. It is suggested that an elevation in the set-point temperature for behavioural thermoregulation can occur in some patients with anorexia nervosa, and that this displacement-5-contribute to the distressing sense of cold which some patients experience.
Propranolol Absorption in Untreated Coeliac Disease
Authors: Sandle G. I. , Ward A. , Rawlins M. D. , Record C. O. 
Published: August 2015

1. To compare the bioavailability and the elimination of propranolol in seven untreated coeliac patients and six normal subjects, plasma concentrations were measured after oral and intravenous propranolol. The bioavailability and clearance of propranolol were similar in both groups.
2. With the use of a perfusion technique, propranolol absorption in the proximal jejunum was found to be decreased by 71% in five untreated coeliac patients, compared with the absorption in four normal subjects.
3. These results indicate that propranolol absorption is decreased in the proximal jejunum in untreated coeliac disease but overall absorption in the small bowel is not impaired.
The Effect of Dietary Sodium on the Blood Pressure Response to Dopamine Infusion in the Conscious Rat
Authors: Obika L. F. O. , Schneider E. G. 
Published: August 2015

1. The influence of dietary sodium intake on the pressor response to intravenously infused dopamine in the conscious rat was studied.
2. Chronic sodium restriction significantly reduced the pressor response to infused dopamine, whereas high sodium diet enhanced the response.
3. Sodium intake is an important determinant of the pressor response to dopamine.
Determination of True Specific Activity of Superoxide Dismutase in Human Erythrocytes
Authors: Saito Takeshi , Ito Keizo , Kurasaki Masaaki , Fujimoto Shun , Kaji Hiroshi , Saito Kazuo 
Published: August 2015

1. Activities, contents and true specific activities of superoxide dismutase (SOD) were determined in human erythrocytes of 105 normal healthy subjects.
2. The mean SOD activity assayed by the inhibition of xanthine autoxidation was 11·0 × 103 units/g of haemoglobin (Hb).
3. The mean SOD content assayed by an immunochemical method was 456 μg/g of Hb.
4. Both activity and content of SOD showed normal distributions, and no significant variations with regard to sex and age were detected.
5. A highly positive correlation between activities and contents of SOD was observed in normal healthy subjects (r = 0·77, P &lt; 0·001).
6. True specific activity was calculated from levels of activity and content of SOD. The mean true specific activity of SOD in human erythrocytes was 23·7 units/μg of SOD.
7. There was no significant difference in true specific activity between young and old subjects.
Assessment of Intestinal Permeability in the Experimental Rat with [3H]Cellobiotol and [14C]Mannitol
Authors: Sandhu J. S. , Fraser D. R. 
Published: August 2015

1. The intestinal absorption of a mixture of [3H]cellobiotol and [14C]mannitol was determined by measuring the 3H/14C ratio in urine after oral administration of the labelled sugars to rats. This index of intestinal permeability was used to identify cellular dysfunction in experimental enteropathy in rats.
2. Rats with mucosal damage induced with ethanol showed an increased uptake of [3H]cellobiotol and a decreased uptake of [14C]mannitol compared with normal controls. The increased 3H/14C ratio in urine reflected the abnormal cell function known to be caused by ethanol.
3. Methotrexate treatment reduced the absorption of the two sugars whereas cetrimide treatment enhanced their absorption. However, in both methotrexate-induced and cetrimide-induced enteropathy the 3H/14C ratio in urine was unaffected by the mucosal damage. Here the permeability change was not related to absorptive dysfunction of the mucosal cells.
4. It is concluded that this labelled sugar absorption test enables the rapid and accurate identification of malfunction of intestinal mucosal cells in the rat. Moreover, the test distinguishes between changes in permeability caused by abnormal cell function and changes caused by gross disturbance of the structure of the mucosal surface.
The Response of Plasma Immunoreactive Adrenocorticotropin, β-Endorphin/β-Lipotropin, γ-Lipotropin and Cortisol to Experimentally Induced Pain in Normal Subjects
Authors: Güllner Hans-Georg , Nicholson Wendell E. , Wilson Margaret G. , Bartter Frederic C. , Orth David N. 
Published: August 2015

1. We examined the effect of ischaemic pain and sustained isometric muscle contraction on plasma immunoreactive γ-lipotropin (γLPH), β-endorphin/β-lipotropin (βEND/βLPH) and corticotropin (ACTH), which are all synthesized from a common precursor (pro-opiocortin), and plasma Cortisol in 10 normal subjects.
2. Experimental pain was produced by inflation to 250 mmHg of a sphygmomanometer cuff, placed above the elbow of the ‘dominant’ arm, after which the subject squeezed a hand dynamometer, loaded to 12 kg, 20 times at 2 s intervals. Blood was drawn before, after 5 and 10 min of pain, and 30 min after release of the cuff. In a control session, the subjects were asked to squeeze the handgrip alone for 5 min at 30% of their maximum strength, a procedure which elevates the blood pressure without causing pain.
3. One subject had unexplained high (30–71 pmol/l) baseline peptide concentrations. Baseline values for the nine other subjects were: ACTH, 7·3 ± 1·9 pmol/l (mean ± sem); γLPH, 18·6 ± 1·0 pmol/l; βEND/βLPH, 10·0 ±1·1 pmol/l; Cortisol, 599 ±55 nmol/l. Neither procedure significantly increased the plasma concentration of ACTH or any other peptide, whereas plasma Cortisol was significantly increased at both 5 min and 10 min. Plasma ACTH was positively correlated with plasma γLPH (r = 0·701; P &lt; 0·001), βEND/βLPH (r = 0·970; P &lt; 0·001) and plasma Cortisol (r = 0·758; P &lt; 0·05).
4. The present study demonstrates that, in normal man, plasma endorphins do not change with experimental ischaemic pain. The rise in plasma Cortisol without concomitant rise in ACTH is not explained, but suggests the action of some other agent at the level of the adrenal cortex.