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Biomedical subjects

J C Djurhuus

Publications and source records attributed to J C Djurhuus.

At least 19 recordsLinked to original sources
PubMed1992

Effects of vasoactive intestinal peptide, peptide histidine methionine, and neuropeptide Y on intracavernous pressure in the rabbit.

In anesthesized white rabbits blood was extracorporeally circulated from the left carotid artery into the penile corporeal bodies with a constant flow rate. Corpus cavernosum pressure (CCP) responses to intracavernous injections of drugs were recorded in animals with aortic nonocclusion and aortic occlusion, respectively. Vasoactive intestinal polypeptide (VIP, 1 microgram, 5 micrograms, and 20 micrograms), dissolved in 0.5 mL volumes, induced no significant increases in CCP compared with equivalent volumes of solvent, but the peptide increased the time interval until return of CCP to steady state level. Peptide histidine methionine induced a significant increase in the maximal CCP obtained in nonocclusion, and the time interval until return of CCP to steady state levels was increased in both aortic nonocclusion and occlusion. Neuropeptide Y produced an increase in the maximal CCP in animals with aortic occlusion, and a minor increase in the time interval until return of CCP values to steady state levels in both aortic nonocclusion and occlusion. Thus, all the peptides tested were capable of influencing the smooth muscle tissues involved in penile outflow regulation.

Animals↗
PubMed1992

Enhanced intrarenal angiotensin II generation in response to obstruction of the pig ureter.

The effect of acute unilateral complete ureteral obstruction (UUO) on renal hemodynamics has been examined in a pig model. Pigs were operated on under general anesthesia, electromagnetic flow probes were inserted around renal arteries, and catheters were implanted in renal veins and aorta for blood sampling. The influence of 15 h of obstruction on the physiological variation in immunoreactive angiotensin II (ANG II) was measured together with detailed analysis of the renal handling of ANG II in anesthetized animals. Pelvic pressure rose significantly within 2 h to a maximum of 59.9 +/- 2.9 cmH2O (n = 10). The ipsilateral renal blood flow (RBF) was reduced by 30% from 319 +/- 35 to 241 +/- 42 ml/min (P = 0.001), whereas contralateral RBF did not change. A temporary significant increase in mean aortic blood pressure was seen during the first 2 h after UUO. Renal vascular resistance increased by 44% in the obstructed kidney from 37 +/- 3 to 55 +/- 9 mmHg.ml-1.min.g during the course of obstruction. Concomitantly, the plasma concentration of immunoreactive ANG II increased from all three sample sites by 8-15 times. This increase was highly significant compared with the sham-operated group. The results show that the pig kidney responds to UUO by a net secretion of ANG II from the ipsilateral kidney. Our observations on the ANG II renal secretion rate suggest that part of the immunoreactive ANG II in the renal venous effluent originated de novo from intrarenal generation.

Angiotensin II↗
PubMed1992

The impact of total unilateral ureteral obstruction on intrarenal angiotensin II production in the polycalyceal pig kidney.

Nine pigs with unilateral complete ureteral obstruction were investigated for 15 hours. Obstruction of the ureter resulted in a maximum intrapelvic pressure of 60 cmH2O within the first hour after obstruction, and a gradual decline to 40 cmH2O during the next 15 hours. In 6 pigs both renal veins were catheterized together with the abdominal aorta allowing measurement of the hormonal difference over the kidney. Plasma angiotensin II, plasma vasopressin and plasma atrial natriuretic peptide concentrations were determined. Arterial concentration of plasma angiotensin II gradually increased from 38.7 pg/ml to 252.3 pg/ml. The highest concentrations of angiotensin II were found from the ipsilateral renal vein. From 1 hour after obstruction and onward there was a negative extraction ratio of angiotensin II from the ipsilateral kidney indicating enhanced intrarenal generation of angiotensin II. No difference in vasopressin was found among the sample sites, but a significant reduction in vasopressin from 15.2 pg/ml to 4.9 pg/ml was found from the ipsilateral renal vein during the 15 hours of unilateral ureteral obstruction. Arterial atrial natriuretic peptide concentrations were higher than renal venous levels at all times. Glomerular filtration was immediately reduced to 58%. It is suggested that an increased ipsilateral generation of intrarenal angiotensin II is at least partly responsible for some of the changes in kidney function during acute obstruction.

Angiotensin II↗
PubMed1992

Monosymptomatic bedwetting.

An update of the pathogenesis and treatment of monosymptomatic bedwetting is presented. This frequently occurring entity seems to have a multifactorial pathogenesis incorporating arousal disturbances and disturbances to the circadian rhythm of diuresis modulating hormones. It has recently been substantiated that the bladder reservoir function in monosymptomatic bedwetting is normal. This is further underlined by the fact that treatment of instability of the bladder has proven futile. In a substantial part of the monosymptomatic bedwetters the changes in circadian rhythm of antidiuretic hormone can be counteracted by desmopressin diacetate (DDAVP), which abolishes the symptom in more than 2/3 of the patients. Monitoring circadian rhythms of arginine vasopressin (AVP) and treatment with DDAVP have led to increased understanding of the pathogenesis of monosymptomatic bedwetting and opened new fields of investigation.

Arginine Vasopressin↗
PubMed1992

The microcirculation of myocutaneous island flaps in pigs studied with radioactive blood volume tracers and microspheres of different sizes.

In order to further improve the understanding of hemodynamic changes in the immediate postoperative phase after elevation of myocutaneous flaps, regional blood flow and arteriovenous (A-V) shunting were measured in rectus abdominis island flaps in 8 pigs. Radioactive microspheres of two sizes (15 and 50 micron) were used. Approximately half (53.4 +/- 6 percent) of the 15-micron microspheres and one-fourth (24.1 +/- 6 percent) of the 50-micron microspheres entering the flap appeared in the venous outflow. Compared with the control area, A-V shunting was significantly increased in muscle and substantially more pronounced in skin. Nutritional blood flow, total blood flow, and vascular volume were increased in muscle and unchanged in skin and subcutis. The lowest tissue hematocrit of 7 +/- 1 percent was found in skin as compared with a central hematocrit of 35 +/- 2 percent. Tissue hematocrit in flap muscle was decreased to 17 +/- 2 percent when compared with control muscle (22 +/- 3 percent), and the mean transit time for blood was correspondingly decreased. Thus vasodilation provided increased perfusion through muscular capillaries and through A-V shunts. Shunting of 15-micron microspheres appeared to take place not only in skin, but also in subcutis and muscle, which challenges the widespread belief that A-V shunting does not occur in muscle.

Animals↗
PubMed1991

[Diurnal enuresis in childhood is effectively treated with terodiline].

Efficacy and tolerance of the anticholinergic calcium antagonist, terodiline (Mictrol), were investigated in a placebo-controlled double-blind cross-over study of 42 children with diurnal enuresis. At a daily dosage of 25 mg, terodiline was well tolerated and, as compared with placebo, resulted in a statistically significant reduction in the daily frequency of wetting. Thus the findings show terodiline to be effective in the treatment of diurnal enuresis, an added advantage being the low incidence of side effects. A full report in English is given in Scand J Prim Health Care 1988; 6:119-24.

Adolescent↗
PubMed1991

Long-term treatment of nocturnal enuresis with desmopressin. A follow-up study.

Eight patients with monosymptomatic nocturnal enuresis (age 11-24 years) were investigated prior to and after 24 weeks of desmopressin treatment in order to evaluate the impact on the endogenous vasopressin secretion and urinary output. No effect on plasma vasopressin, diurnal urinary volume, and urinary osmolality were found after this long-term treatment. Overall no changes in either body weight, blood pressure, or hematological variables were demonstrated. This supports previous findings that the treatment appears to be well tolerated and free of side effects in longer term.

Adolescent↗
PubMed1991

Experimental evaluation of furosemide renography in unobstructed and partially obstructed upper urinary tracts in pigs.

To evaluate the reliability and the constancy of the furosemide renography an experimental evaluation of the test has been performed. A standardized unilateral partial proximal ureteral obstruction was applied to 11 pigs. Preoperatively and again weekly in the three weeks following obstruction a furosemide renogram (FR) was done. The furosemide renography was a very constant parameter in the unobstructed kidney (85%) and in the partly obstructed kidney (85%). A type I FR pattern (O'Reilly classification) was an exact indicator of an unobstructed pelvis. After partial ureteral obstruction, an immediate change in the FR pattern was seen either into type II or type IIIa renography. In this experimental study furosemide renography was found to be a reliable tool in the differentiation between the unobstructed normal renal pelves and the partly obstructed dilated renal pelves.

Animals↗
PubMed1991

Urethral pressure and pressure variations in healthy fertile and postmenopausal women with reference to the female sex hormones.

The impact of female sex hormones on the rhythmic urethral pressure variations (UPV) was analysed based on data from one hour urethral pressure recordings from 10 healthy fertile female volunteers measured three times during the menstrual cycle and from 12 healthy postmenopausal women measured twice within two months. The mean maximum urethral pressure (mMUP) and the mean maximum urethral closure pressure (mMUCP) had a median value of 66.5 (Interquartile 58.0-86.0) and 60.0 (49.0-80.0) cm.H2O respectively in the healthy fertile females. The postmenopausal women had a significantly lower mMUP and mMUCP of 55.5 (48.5-58.5) and 43.5 (35.5-47.0) cm.H2O) respectively. Rhythmic UPV was recorded inhealthy fertile and postmenopausal women. Frequency analysis of the UPV revealed a frequency spectrum from 0.0015 to 0.035 Hz on top of which were respiration fluctuations and vascular pulsations. The UPV amplitude was related to the mMUP and increased with increasing mMUP. The parameters analysed were stable during the menstrual cycle and during menopause. Thus no difference in the UPV frequencies or amplitudes was observed between the healthy fertile and the postmenopausal women. The investigation shows that the pressure variation in urethra apparently is not modulated by female sex hormones.

Adult↗
PubMed1991

Diurnal variation of plasma atrial natriuretic peptide in normals and patients with enuresis nocturna.

The circadian variation of plasma atrial natriuretic peptide (ANP) in relation to urinary excretion of sodium (UNa) and potassium (UK) as well as clearance of creatinine (Ccrea) was assessed in 15 juvenile patients with enuresis nocturna and compared with 11 age-, sex-, and weight-matched normal subjects. Normal juveniles showed a highly significant diurnal variation (p less than 0.001) of plasma ANP with diurnal peak levels at midnight (0000 hours) and minimum levels at 0400 hours. Enuretic patients showed a similar diurnal rhythmicity with normal levels during day and night. In normals both UNa and UK showed significant diurnal rhythmicity with a marked reduction from daytime to night-time. Although the total diurnal excretions of UNa and UK were similar to normals, patients with enuresis showed abnormal diurnal variation in both UNa (p less than 0.05) and UK (p less than 0.01). The abnormal circadian rhythm of UNa and UK in enuretics seemed to be caused by abnormal tubular handling as similar abnormalities were found in the fractional excretions and as the circadian variation of Ccrea was normal. Especially during the first hours of sleep (2200 hours to 0000 hours), the patients showed polyuria (230 +/- 138 ml vs 116 +/- 58 ml, p less than 0.01), natriuresis (20.9 +/- 16.3 mmol l-1 vs 10.7 +/- 6.8 mmol l-1, p less than 0.01), and kaliuresis (7.3 +/- 6.3 mmol l-1 vs 3.7 +/- 2.3 mmol l-1, p less than 0.05), despite normal levels of plasma ANP. In conclusion, the study describes the diurnal variation of plasma ANP in relation to urinary excretion of sodium and potassium in a juvenile normal population. Patients with nocturnal enuresis show abnormal diurnal rhythmicity in the urinary excretion of sodium and potassium that is not correlated to the plasma levels of ANP.

Adolescent↗
PubMed1991

Arteriovenous shunting and regional blood flow in myocutaneous island flaps: an experimental study in pigs.

In eight pigs, total blood flow, regional capillary blood flow distribution, and arteriovenous (AV) shunting were studied during the first 4 postoperative hours after elevation of a myocutaneous rectus abdominis island flap. Capillary blood flow and AV shunting were measured using radioactive microspheres before flap creation and 1 and 4 hours after surgery. Total blood flow, measured continuously as venous outflow, increased in the first postoperative hour (p less than 0.05). Elevation of the flap caused a slight decrease in skin capillary blood flow (p less than 0.05), whereas muscular capillary blood flow increased (p less than 0.01). AV shunting accounted for 50 percent of the total flap blood flow, whereas it was negligible in the abdominal wall prior to flap elevation. Thus stalk blood flow, skin appearance, and skin temperature may be poor indicators of nutritional capillary perfusion. However, the clinical and nutritional consequences of these findings remain to be established.

Analysis of Variance↗
PubMed1991

Impedance planimetry: a new approach to biomechanical intestinal wall properties.

This paper surveys impedance planimetry, a technique based on the measurement of electrical impedance for estimation of active and passive biomechanical wall properties of the intact intestine. The paper mainly concerns methodological aspects of the recording technique and possible sources of error. Furthermore, the historical background concerning developments of the technique and physiological results during the last two decades are described.

Animals↗
PubMed1991

Biomechanical wall properties of the porcine rectum: a study using impedance planimetry.

The aim was to investigate biomechanical wall properties of the porcine rectum by way of manometry and impedance planimetry. Distension of a balloon inserted into the rectum with definite pressure steps up to 80 cm H2O was done for simultaneous recording of pressure and the balloon cross-sectional area (Bcsa). Viscoelastic wall properties were derived in terms of compliance. Besides eliciting the ascending peristaltic reflex and relaxation of the internal anal sphincter, the balloon inflation elicited a phase of rapid Bcsa increase followed by an accommodation phase of slow Bcsa increase to a steady-state Bcsa, reached within 3 min. The Bcsa increased in a nonlinear way with increasing balloon pressures with only a minimal increase from 70 to 80 cm H2O. Rectal compliance decreased in a nonlinear way with increasing distension pressure.

Animals↗
PubMed1991

Tissue oxygen tension in myocutaneous flaps. Correlation with blood flow and blood gases.

The relationship between tissue oxygen tension (PO2) and blood flow, blood gas tensions, oxygen delivery, and oxygen consumption was investigated in myocutaneous island flaps in 24 pigs. The tissue PO2 was measured by the silicone rubber tonometer technique. Capillary blood flow was increased during the first 3-4 hours after implantation of tonometers and they must, therefore, be implanted 3-4 hours before use. After raising the flap, mean (SEM) total flap blood flow increased from 11.2 (0.8) ml/min to 16.0 (1.3) ml/min within the first three hours. Mean (SEM) subcutaneous tissue PO2 decreased from 9.5 (0.6) kPa to 5.2 (0.7) kPa over six hours after the procedure, whereas muscle PO2, blood oxygen tension, and arteriovenous oxygen difference were unchanged. Hence, both the supply to, and use of oxygen in, the flap increased. Muscular and subcutaneous oxygen tensions were about 3 and 1 kPa, respectively, lower than venous oxygen tension. Tissue PO2 did not correlate with blood flow, blood oxygen tensions, arteriovenous differences in oxygen tension, or with oxygen supply in a cross section of animals. Tissue PO2 seems to reflect accurately the balance between oxygen supply and consumption, which might be the most useful indicator for continuous flap monitoring.

Animals↗
PubMed1991

Continuous direct tissue oxygen tension measurement. A new application for an intravascular oxygen sensor.

An oxygen tension measurement equipment, developed for continuous intravascular monitoring was tested as a direct tissue oxygen tension meter. The sterile disposable oxygen probe consists of a Clark type polaro-graphic bipolar electrode placed in a 5 cm long flexible polyethylene catheter (OD 0.55 mm). The probe is easily placed, e.g. in subcutaneous tissue or muscle, with the aid of an introduction needle. In vitro measurements as well as subcutaneous and intramuscular readings were performed. The animals were subjected to various experimental conditions such as different inspiratory oxygen fractions, hypovolemia, and circulatory impairment. Results were comparable to those obtained with previously used and well characterized tissue oxygen tension measurement equipment. The clinical applicability of the oxygen sensor for tissue oxygen measurement was assessed in one patient by 40 hours' surveillance in a free myocutaneous flap. The procedure was simple and implied minimal discomfort for the patient.

Animals↗
PubMed1990

The impact of unilateral ureteral obstruction on pelvic and parenchymal transit times in the pig kidney.

In 10 female pigs a partial unilateral ureteral obstruction was investigated for 3 weeks. The pigs were monitored with 131I-iodo-hippuran scintigraphies before obstruction and once a week during the course of obstruction. Parenchymal and pelvic mean transit times were calculated by deconvolution analysis. Before the pigs were killed, pelvic pressure and volume were measured. During the course of obstruction there was a slight, but significant (P less than or equal to 0.05) difference in renographical split function between the 2 sides. Parenchymal transit times increased moderately ipsilaterally during the 1st and 2nd week after obstruction and a significant difference (P less than 0.02) appeared in the 2nd week compared to the contralateral side, which was unchanged during the course of obstruction. Pelvic transit times increased steadily ipsilaterally during the course of obstruction and the opposite took place contralaterally. A fair correlation (r = 0.65) was found between parenchymal transit time and pelvic baseline pressure. Pelvic transit times were prolonged at any time after obstruction and significantly correlated to the presence of obstruction. The study suggests that interpretation of the obstructed renogram will encounter analysis of both parenchymal and pelvic transit times in cases where renal function is moderately reduced.

Animals↗