bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetic Influence on Brain Catecholamines: High Brain Noradrenaline in Salt-Sensitive Rats
Authors: Iwai Junichi , Friedman R. , Tassinari Lorraine 
Published: August 2015

1. Rats genetically sensitive to salt-induced hypertension showed higher levels of plasma noradrenaline and adrenaline than rats genetically resistant to hypertension.
2. The hypertension-sensitive rats had higher hypothalamic noradrenaline and lower adrenaline than resistant rats.
3. In response to a high salt diet brain-stem noradrenaline increased in sensitive rats and resistant rats exhibited a decrease on the same diet.
Pathophysiological Changes Associated with Stress-Induced Hypertension in the Borderline Hypertensive Rat
Authors: Lawlerw J. E. , Barker G. F. , Hubbard J. W. , Schaub R. G. 
Published: August 2015

1. This study sought to develop an animal model which would be prone to stress-induced hypertension without spontaneously developing it.
2. Eighteen male rats, F1 offspring of spontaneously hypertensive × Wistar-Kyoto rats, had tail-cuff systolic blood pressures of 152 mmHg at 12 weeks of age. Animals were randomly assigned to three groups of six each: experimental (subjected to ‘conflict’ 2 h daily for 12 weeks), restraint control (placed in conditioning cages but not subjected to conflict) and maturation control (neither restrained nor stressed).
3. Systolic blood pressure rose significantly in experimental animals to 186 mmHg. Experimental animals studied for a 10 week follow-up period without conflict maintained the elevated pressure. In addition, these animals showed myofibrillar degeneration and an elevation in heart weight/body weight ratios. Restraint animals showed a modest elevation in pressure during the study, but not during the 10 week follow-up. Maturation animals showed no changes in blood pressure.
4. The development of a model of hypertension combining genetics with psychological stress may serve as a means for determining the factors involved in triggering and sustaining stress-induced hypertension which may prove relevant to essential hypertension in man.
Impaired Autoregulatory Responses in Contralateral Kidneys of Two-Kidney, One-Clip Hypertensive Rats
Authors: Ploth D. W. , Roy R. N. , Huang Wann-Chu , Navar L. G. 
Published: August 2015

1. Micropuncture and clearance experiments in two-kidney, one-clip renal vascular hypertensive rats examined the ability of the kidney contralateral to renal vascular stenosis to maintain renal function during conditions of reduced renal arterial blood pressure.
2. At their respective spontaneous blood pressures, renal vascular resistance was higher and glomerular filtration rate (GFR) and renal blood flow were not different in the contralateral kidneys of the hypertensive rats (170 ± 5 mmHg) compared with normal animals (129 ± 1 mmHg). Urine flow and absolute and fractional excretion of electrolyte were greater from the kidneys of the hypertensive animals. However, pressures in cortical structures were similar in the two groups.
3. As blood pressure was reduced acutely, the kidney contralateral to the renal artery stenosis achieved only small decreases in renal vascular resistance that failed to allow GFR, renal blood flow or pressures in cortical structures to be maintained. In contrast, normal rats efficiently autoregulated renal vascular resistance to allow GFR, renal blood flow and cortical pressures to be unchanged as blood pressure was altered between 130 and 115 mmHg. Urine flow and electrolyte excretion decreased to a greater extent in the hypertensive kidneys; at comparable blood pressure these indices of excretory function were not different in the two groups.
4. These observations indicate that the contralateral kidney can maintain normal haemodynamic and glomerular function only at elevated blood pressure and suggest the possibility that the impaired capacity to autoregulate renal resistances may contribute to the maintenance of hypertension observed in this model.
Chronic Lability of Arterial Pressure in the Rat Does Not Evolve into Hypertension
Authors: Talman W. T. , Alonso D. R. , Reis D. J. 
Published: August 2015

1. In rats, electrolytic lesions of the A2 group of catecholamine neurons result in lability of arterial pressure without hypertension.
2. To establish whether labile arterial pressure, when chronic, will lead to fixed hypertension, we placed lesions in the A2 area of adult male Sprague-Dawley rats and measured mean arterial pressure, heart rate and their variability (expressed as the standard deviation) 11 months later. Controls were age-matched, unoperated or sham-operated rats.
3. In rats with A2 lesions: (a) the mean arterial pressure was lower (103 ± 7.5 mmHg; n = 6; P&lt;0.05) than in sham-operated (123 ± 4.7 mmHg; n = 4) or unoperated (120 ± 3.1 mmHg; n = 9) controls; (b) the standard deviation of mean arterial pressure was higher (16 ± 1.8 mmHg; P&lt;0.001) than in sham-operated (5 ± 0.7 mmHg) or unoperated controls (7 ± 0.6 mmHg); (c) the mean and standard deviation of heart rate did not differ between groups. No histopathological changes were detected in the A2 group.
4. Chronic lability of arterial pressure does not evolve into sustained hypertension nor does it induce systemic lesions.
Visualization of the Renal Arteries during Excretory Urography
Authors: Ingrisch H. , Holzgreve H. , Frey K. W. 
Published: August 2015

1. Intravenous excretory urography was modified and expanded in order to visualize the aorta and the renal arteries.
2. The new procedure consists of the rapid intravenous injection of contrast medium, determination of the circulation time between the injection site and abdominal aorta, tomography with a multileaf cassette with five films (angiotomography) and continuation of the investigation as with routine excretory urography.
3. In 343 patients a total of 739 single or multiple renal arteries were identified at least partially. Of these, 83% could be clearly outlined between the aorta and the first division.
4. In 71 hypertensive patients angiography and angiotomography were separately evaluated. With angiotomography all 165 single or multiple renal arteries seen with angiography were visualized at least partially, whereas a total of 149 (90%) of renal arteries could be completely outlined between the aorta and the first division of the renal arteries.
5. A sensitivity for the presence of renal artery stenosis of 92% and a specificity for the absence of artery stenosis of 99% can be calculated for angiotomography in the diagnosis of renal artery stenosis.
6. Thus this method permits the detection or exclusion of renal artery stenosis in almost three-quarters of patients with hypertension, without angiography.
Influence of Sympatholytic Drugs on the Cardiovascular Response to Isometric Exercise
Authors: Watt S. J. , Thomas R. D. , Belfield P. W. , Goldstraw P. W. , Taylor S. H. 
Published: August 2015

1. The effects of single oral doses of various sympatholytic drugs on the heart rate and blood pressure increases during isometric handgrip contraction were studied in six healthy subjects.
2. Bethanidine reduced both the systolic and diastolic increases in pressure. Clonidine reduced the systolic but not the diastolic increase. Oxprenolol alone or in combination with phentolamine or phenyoxybenzamine failed to influence the pressor response.
3. The increase in systemic blood pressure associated with sustained contraction of voluntary muscle appears to be relatively resistant to acute sympathetic adrenoreceptor blockade in man.
Cardiovascular and Autonomic Reflexes in Haemodialysis Patients
Authors: Naik R. B. , Mathias C. J. , Wilson C. A. , Reid J. L. , Warren D. J. 
Published: August 2015

1. Blood pressure and heart rate responses to head-up tilt, standing, the Valsalva manoeuvre, sustained handgrip and cutaneous cold were measured in 27 haemodialysis patients (10 of whom had episodes of haemodialysis-induced hypotension) and 15 control subjects to assess autonomic nervous function. Plasma nor-adrenaline levels were measured at rest and during head-up tilt.
2. Mean resting supine blood pressure, heart rate and plasma noradrenaline levels were higher in haemodialysis patients than in the control subjects. There was no fall in blood pressure during head-up tilt or standing. The ratio of the R-R intervals of the thirtieth and the fifteenth heart beat after standing (30: 15) was lower in the patients; this may be related to their higher resting heart rate. Head-up tilt raised plasma noradrenaline levels in both groups. Heart rate responses to the Valsalva manoeuvre were similar in the patients and control subjects.
3. Systolic blood pressure and heart rate responses to sustained handgrip were similar in both groups. Diastolic and mean blood pressure changes, however, were lower in the patients. The blood pressure and heart rate responses to cutaneous cold were similar in the patients and control subjects.
4. We conclude that generalized autonomic nervous dysfunction does not appear to cause haemodialysis-induced hypotension in patients with chronic renal failure on maintenance haemodialysis.
Development of a Technique for Measuring the Oxidation Rate of a 14C-Labelled Substrate from 14CO2 Production without the Need for Collection of Expired Air
Authors: Clague M. B. , Keir M. J. , Wright P. D. 
Published: August 2015

1. A method is proposed for the determination of the rate of oxidation of 14C-labelled substrates in man from blood sampling only.
2. The method was verified by simulating release of 14C into the bicarbonate pool of patients by using a constant-rate infusion of sodium [14C]bicarbonate, the plasma level of total 14CO2 (d.p.m. ml−1 70 kg−1) correlating well (r = 0.878, P = 0.001) with the infusion rate (μCi/h).
3. Techniques involved in employing this method are discussed, particularly in the light of errors involved.
Radioimmunoassay of Human Cardiac Tropomyosin in Acute Myocardial Infarction
Authors: Cummins P. , McGurk B. , Littler W. A. 
Published: August 2015

1. Tropomyosin was prepared from fresh human myocardium and antisera raised in rabbits. A sensitive radioimmunoassay was developed for the detection of human cardiac tropomyosin in human sera down to levels of 1 ng/ml.
2. Values for human cardiac tropomyosin in normal patients ranged from less than 1 to 3 ng/ml. In 18 patients with acute myocardial infarction all had elevated tropomyosin levels ranging from 41 to above 200 ng/ml with a mean peak level of 101 ng/ml. In this study there were no false positive or false negative results.
3. In the initial stages of infarction the time course of appearance and peak levels of cardiac tropomyosin, total creatine kinase and creatine kinase MB isoenzyme were similar. Although total creatine kinase and creatine kinase MB isoenzyme levels were normal after 72 h in patients with single, uncomplicated infarction, cardiac tropomyosin levels were still significantly elevated above normal after this time, being 30–60% of peak values.
4. Radioimmunoassay of human cardiac tropomyosin may prove useful in the diagnosis and in the management of patients with acute myocardial infarction, particularly in the long-term postinfarction period.
Aggravation of Hypertension in Spontaneously Hypertensive Rats by Heymann Nephritis
Authors: Tikkanen I. , Miettinen A. , Fyhrquist F. , Törnroth T. 
Published: August 2015

1. To explore the effect of nephritis on development of genetic hypertension we immunized 10-week-old spontaneously hypertensive rats with purified rat kidney brush-border antigen. This induces Heymann nephritis (autologous immune complex nephritis), which does not elevate blood pressure in normal rats.
2. Nephritis developed in 11 of the 12 immunized animals, and systolic blood pressure rose to a significantly higher level than in the non-immunized spontaneously hypertensive rats within 4 weeks. Blood pressure remained higher in the immunized rats at 17 weeks, heart weights were greater, but creatinine clearance remained unchanged.
3. At 6 weeks, urinary sodium excretion was greater in the immunized spontaneously hypertensive rats, whereas at 17 weeks, sodium excretion was decreased in these animals along with reduced serum protein concentration, packed cell volume and plasma renin activity, as compared with that of the controls.
4. Development of hypertension in nephritic rats, therefore, appeared unrelated to sodium excretion; signs of volume expansion emerged later.
5. Acceleration of the development of spontaneous hypertension by Heymann nephritis, also leading to sustained higher blood pressure levels than in spontaneously hypertensive rats, offers a new approach to experimental study of immune mechanisms behind acceleration of pre-existing hypertension. This may have important bearings on essential hypertension as well.
Urine Composition in Normal Subjects after Oral Ingestion of Oxalate-Rich Foods
Authors: Finch A. M. , Kasidas G. P. , Rose G. A. 
Published: August 2015

1. Urinary composition was studied in nine healthy adults on unrestricted diet and low-oxalate diet with and without individual oxalate-rich foods.
2. Urine oxalate was constant on the low-oxalate and constant high-oxalate diets and only fluctuated greatly on unrestricted diet.
3. Urine oxalate was mainly due to dietary oxalate which accounts for up to two-thirds of urinary oxalate.
4. Urine oxalate was unaffected by urine volume.
5. Varying percentages of dietary oxalate were absorbed depending on the nature of the foodstuff.
6. Although tea was the main source of dietary oxalate in some people it, like strawberries, did not represent a real risk factor. Chocolates, peanuts, beetroot, rhubarb and spinach were considered as high-risk foods.
7. Calcium oxalate crystalluria at 4°C was increased significantly when the oxalate-rich foods were taken. When urine was examined at 37°C no increase in crystalluria was found.
Opposite Effects of Captopril on Angiotensin I-Converting Enzyme ‘Activity’ and ‘Concentration’; Relation between Enzyme Inhibition and Long-Term Blood Pressure Response
Authors: Boomsma F. , de Bruyn J. H. B. , Derkx F. H. M. , Schalekamp M. A. D. H. 
Published: August 2015

1. The relationship between the antihypertensive action of captopril and its inhibitory effect on angiotensin I(ANG I)-converting enzyme has been investigated. Converting enzyme was measured in plasma by its ability to generate hippuric acid from the synthetic substrate hippuryl-l-histidyl-l-leucine. Inhibition by captopril appeared transient on storage of the plasma samples at −20°C, so that measurements in such samples were not a valid index of the effect in vivo.
2. Rapid reversal of captopril's inhibitory effect on ANG I-converting enzyme in plasma was achieved by the addition of N-ethylmaleimide (0.1 mmol/l). In this way an estimate of converting enzyme ‘concentration’ was obtained both in stored and in freshly prepared plasma samples. Measurements of converting enzyme ‘activity’ in freshly prepared samples, in the absence of N-ethylmaleimide, were used as an index of inhibition in vivo.
3. In eight hypertensive subjects ANG I-converting enzyme ‘concentration’ did not change after a single oral 100 mg dose of captopril. Long-term treatment of 10 hypertensive subjects with captopril was associated with a gradual increase in converting enzyme ‘concentration’ from 29 ± 2 to 47 ± 3 m-units/ml (mean ± sem) over a period of several weeks. In contrast, captopril caused a rapid fall of converting enzyme ‘activity’.
4. Abrupt withdrawal of captopril after long-term treatment caused a gradual decrease in ANG I-converting enzyme ‘concentration’ to the control value. In contrast, converting enzyme ‘activity’ rose rapidly and became equal to enzyme ‘concentration’ 2 days after the drug had been stopped.
5. The concentration of enzymatically active renin in plasma rose from 13 ± 3 to 81 ± 34 μ-units/ml during long-term captopril treatment (mean ± sem). Blood pressure fell from 168 ±4/108 ± 3 to 140 ± 3/90 ± 3 mmHg and had not returned to the control value in the first week after the drug had been stopped, despite the fact that circulating active renin and ANG I-converting enzyme ‘activity’ were elevated.
6. It is concluded that long-term inhibition of ANG I-converting enzyme by captopril is associated with an increased plasma concentration of this enzyme. The results also suggest that the level of converting enzyme ‘activity’ in plasma is not the only factor that determines the long-term effect of captopril on blood pressure.
The Contribution of Upper Airway and Inspiratory Muscle Mechanisms to the Detection of Pressure Changes at the Mouth in Normal Subjects
Authors: Gandevia S. C. , Killian K. J. , Campbell E. J. M. 
Published: August 2015

1. With standard psychophysical techniques the ability of normal subjects to detect negative pressures applied at the mouth was estimated.
2. The ability to detect changes in pressure when confined to the upper airway by closure of the glottis was less than when the pressures were transmitted below the glottis and were actively overcome by inspiratory muscle contraction.
3. The ability to detect changes in pressure with the glottis open was also impaired by passive ventilation and vibration of the chest.
4. Our results imply that the most sensitive mechanism for the detection of negative pressures applied at the mouth involves afferent information from active inspiratory muscle contraction.
Postprandial Thermogenesis in Obesity
Authors: Shetty P. S. , Jung R. T. , James W. P. T. , Barrand M. A. , Callingham B. A. 
Published: August 2015

1. The thermogenic response and changes in plasma substrates and hormones were tested after a liquid meal in lean, obese and formerly obese women.
2. Subjects with a family history of obesity tested either while obese or after slimming to a normal weight had a thermogenic response, which was only half that of the lean group.
3. The immediate response in plasma glucose and insulin was greater in the lean subjects, but the sustained changes in circulating substrates did not differ in the three groups. Thyroidal hormone concentrations did not alter postprandially: venous noradrenaline levels rose in the obese groups only.
4. The differences in postprandial thermogenesis at rest would reduce the energy requirements of subjects with familial obesity, but they still had a metabolic rate estimated to be nearly 1MJ (240 kcal)/day in excess of the lean group so additional thermogenic defects must exist for familial obesity to be explained solely on a metabolic basis.
Renal Prostaglandins and Water Balance: Studies in Normal Volunteer Subjects and in Patients with Central Diabetes Insipidus
Authors: Düsing R. , Herrmann R. , Glänzer K. , Vetter H. , Overlack A. , Kramer H. J. 
Published: August 2015

1. In six healthy volunteer subjects polydipsic water loading significantly increased urine volume from 1203 ± 242 (sem) to 5072 ± 320 ml/24 h (P &lt; 0.001) with a significant decrease in urinary osmolality. This increase in urine volume by more than fourfold was associated with a slight increase in urinary excretion of prostaglandin E2 from 466 ± 66 to 1017 ± 174 pmol/24 h (P = 0.05).
2. In five patients with central diabetes insipidus mean urine volume of 10 838 ± 107 ml/24 h was reduced to 1205 ± 204 ml/24 h (P &lt; 0.001) by treatment with 1-desamino-8-arginine vasopressin (desamino-[Arg8]vasopressin; 15 μg/day) with a significant rise in urinary osmolality. Desamino-[Arg8]vasopressin treatment was associated with a significant increase of suppressed urinary excretion of prostaglandin E2 (PGE2) in four of these patients from 246 ± 66 to 2643 ± 677 pmol/24 h (P &lt; 0.01).
3. Concomitant treatment with indomethacin in addition to desamino-[Arg8]vasopressin significantly suppressed urinary excretion of PGE2 and significantly increased urinary osmolality as compared with treatment with desamino-[Arg8]vasopressin alone.
4. Desamino-[Arg8]vasopressin significantly increased urinary excretion of adenosine 3′:5′-cyclic. monophosphate (cyclic AMP). However, there was no further change in urinary excretion of cyclic AMP during concomitant indomethacin treatment.
5. The results suggest that urine flow itself is not an important determinant of urinary PGE2 excretion. In patients with central diabetes insipidus the urinary concentrating response to desamino-[Arg8]vasopressin is enhanced during inhibition of prostaglandin synthesis without changes in urinary excretion of cyclic AMP.
Pattern of Breathing during Cigarette Smoking
Authors: Rees P. J. , Clark T. J. H. 
Published: August 2015

1. Recordings were made of the pattern of breathing during and after smoking a cigarette in 14 smokers and nine non-smokers.
2. The most consistent effect was an increase in tidal volume during smoking which reverted to baseline over 1–2 min. Changes in breath times were smaller and less consistent. Similar effects were observed with intermittent inhalations of charcoal.
3. In four subjects the tidal volume response was significantly decreased by oropharyngeal and laryngeal anaesthesia with lignocaine.
4. Filtration of particulate matter from the cigarette smoke delayed the onset of changes in tidal volume.
5. The changes probably represent an irritant response with stimulation at laryngeal or oropharyngeal level.
The Excretion of Isotope in Urea and Ammonia for Estimating Protein Turnover in Man with [15N]Glycine
Authors: Fern E. B. , Garlick P. J. , McNurlan Margaret A. , Waterlow J. C. 
Published: August 2015

1. Four normal adults were given [15N]-glycine in a single dose either orally or intravenously. Rates of whole-body protein turnover were estimated from the excretion of 15N in ammonia and in urea during the following 9 h. The rate derived from urea took account of the [15N]urea retained in body water.
2. In postabsorptive subjects the rates of protein synthesis given by ammonia were equal to those from urea, when the isotope was given orally, but lower when an intravenous dose was given.
3. In subjects receiving equal portions of food every 2 h rates of synthesis calculated from ammonia were much lower than those from urea whether an oral or intravenous isotope was given. Comparison of rates obtained during the post-absorptive and absorptive periods indicated regulation by food intake primarily of synthesis when measurements were made on urea, but regulation primarily of breakdown when measurements were made on ammonia.
4. These inconsistencies suggest that changes in protein metabolism might be assessed better by correlating results given by different end-products, and it is suggested that the mean value given by urea and ammonia will be useful for this purpose.
Vasopressin in the Plasma of Stroke-Prone Spontaneously Hypertensive Rats
Authors: Rascher W. , Weidmann E. , Gross F. 
Published: August 2015

1. Plasma concentration of arginine vasopressin, plasma osmolality and packed cell volume were measured in stroke-prone spontaneously hypertensive rats (SHRSP) and in normotensive Wistar-Kyoto (WKY) rats at different ages.
2. In young and in adolescent SHRSP, at 6, 9 and 12 weeks of age, plasma concentration of vasopressin was diminished as compared with age-matched WKY rats (P &lt; 0.01), whereas, in 18-week-old rats, the difference was not significant (P &gt; 0.05). In contrast, in 24-week-old rats, plasma vasopressin was elevated as compared with WKY rats of the same age (P &lt; 0.01).
3. In none of the age groups did plasma osmolality differ between the two strains of rats, but in all groups packed cell volume in SHRSP was higher than in WKY rats.
4. During a 48 h period of dehydration, plasma vasopressin concentrations increased similarly in SHRSP and in WKY rats of 6 and 12 weeks of age respectively.
5. It is concluded that vasopressin does not contribute to the development of high blood pressure in SHRSP rats. The reduced plasma concentration of vasopressin may account for the decreased plasma and blood volume and the slightly elevated plasma sodium concentration observed in young SHRSP rats.