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Biomedical subjects

H Colstrup

Publications and source records attributed to H Colstrup.

At least 37 records · Page 2Linked to original sources
PubMed1993

In vivo evaluation of visco-elasticity in a biological tube. Part 2. Application of a mechanical model.

Based on a theoretical model, the urethral stress-relaxation response following a sudden forced dilatation was studied in ten healthy female volunteers. The energy dissipation following a sudden urethral dilatation proved to follow the function Y = Z + C alpha e-t/tau alpha + C beta e-t/tau beta. Hence, a mechanical model was chosen, consisting of two Maxwell elements and one Hooke element coupled in parallel. The decay in force following deformation may be described as F = F(o) exp (-t.E/eta) for each Maxwell element. Thus, it was possible to determine the elastic E and viscous eta coefficients for the participating mechanical equivalents in the model, and thereby quantitatively describe the visco-elastic properties in the urethra. The reproducibility of the elastic and the viscous coefficients proved to be fairly high, and they seemed to be unaffected by the size of dilatation. On the other hand, the rate of dilatation clearly influenced the computed parameters. However, this phenomenon was easily explained by the duration of the deformation, which allowed the viscous elements to move before any measurements were performed. The present method permits in vivo evaluation of the elastic and viscous properties of the urethra, as well as other accessible biological tubes, and may be of value in the description of normal physiological and pathophysiological behaviour of the structures studied.

Adult↗
PubMed1993

The influence of beta-adrenoceptor and muscarinic receptor agonists and antagonists on the static urethral closure function in healthy females.

The effects of terbutaline, propranolol, carbachol, and atropine on the static urethral closure function were investigated in 20 healthy women. Terbutaline caused a statistically reduction of the urethral pressure in the high pressure zone, but not at the bladder neck or in the distal urethra. The other drugs caused no significant pressure changes. None of the drugs used produced significant changes in the static viscoelastic properties, elastance, and hysteresis of the resting urethra. It is suggested that terbutaline partly reduces intraurethral pressure by reducing muscular tone in the rhabdosphincter and pelvic floor.

Adrenergic beta-Agonists↗
PubMed1993

A model of reversible uremia employing isogenic kidney transplantation in the rat. Reversibility of secondary hyperparathyroidism.

Kidney transplanted patients with normalized kidney function may still exhibit a variety of problems such as bone problems, vascularly problems, and hormonal dysfunctions. A part of the symptoms may be persisting uremic symptoms, secondary to the pretransplanted period of chronic uremia. An experimental rat model, designed to the study of the reversibility of the chronic uremic implications is therefore described. A stable, severe chronic uremia was induced by 5/6 nephrectomy to inbred Lewis rats. Ten weeks later uremia was reverted by a successful isogenic rat kidney transplantation. During the period of chronic uremia the p-urea was elevated to an average of 21.8 +/- 0.9 mmol/l and p-creatinine to 105.7 +/- 5.7 microM/l. The isogenic kidney transplantation resulted in reestablishment of normal kidney function with an average level of p-urea of 7.6 +/- 0.2 mmol/l and p-creatinine 42.5 +/- 1.9 microM/l perfectly corresponding to the sham-operated rats, i.e. one-kidney rats. Reversibility of the secondary hyperparathyroidism due to chronic uremia was investigated in the model. In rats with chronic renal failure PTH increased from 52 +/- 4.9 pg/ml to 152 +/- 12.2 pg/ml and was normalized after transplantation. It is therefore concluded that the present described technique of introducing long term uremia followed up by a successful kidney transplantation in the rat may be a useful model to study the reversibility of different uremic manifestations.

Animals↗
PubMed1993

The effect of pharmacological stimulation and blockade of autonomic receptors on the urethral pressure and power generation during coughing and squeezing of the pelvic floor in healthy females.

The effect of autonomic receptor agonists and antagonists on the urethral pressure and power generation during coughing and squeezing of the pelvic floor has been evaluated in 30 healthy females. The measurements were carried out at the bladder neck, in the high pressure zone, and distally in the urethra. The used drugs (noradrenaline, prazosin, terbutaline, propranolol, carbachol and atropine) caused no significant change in the pressure and power generation. The clinically relevant influence of drugs on the urethral closure function should be re-appraised when based on profilometry in the resting state. The results support that the effect of the autonomic nervous system on the urethral closure function is insignificant in healthy women. They furthermore indicate that investigations on the ability to secure continence cannot be based solely on resting pressure profilometry, but should be accomplished by measurements during stress episodes.

Adult↗
PubMed1992

[Testing an ultrasonic scanner for determination of urinary bladder volume].

Bladderscan BVI 2000 is a portable ultrasound scanner, specially constructed for determination of bladder volume. We have tested this scanner for accuracy, systematic errors and the training required to use it. The bladder volumes measured by ultrasound scanning were compared with the true volumes. Fifty-six measurements were made. We found the accuracy of BVI 2000 sufficient to determine bladder volumes as either small or large. We found no systematic errors. No special training is required to use the scanner. The device is thus useful in most clinical situations when greater accuracy than indicated here is not necessary.

Evaluation Studies as Topic↗
PubMed1992

[PermCath as intravenous access in chronic hemodialysis].

PermCath is a dual-lumen silicone catheter for permanent venous access for hemodialysis. During an observation period from 1 July 1988 to 30 June 1991, 49 PermCath were inserted in 32 patients. In 24 patients (75%), the PermCath was used as sole method of access for hemodialysis through the observation period. Six of the 24 patients required changing of the catheter once, and in three patients the PermCath functioned properly only after the third insertion of a PermCath. In eight patients, vascular access could not be accomplished using the PermCath and these patients were all hemodialyzed through another vascular access. Four patients developed bacteraemia and one patient developed thrombosis of the subclavian vein during the observation period. Insertion of the PermCath is easy and, in case of malfunction, changing or removal of the catheter is easily accomplished. The PermCath is recommended as an alternative to existing techniques for intravenous access for hemodialysis.

Adolescent↗
PubMed1992

Urethral pressure--which one?

Urethral pressure was investigated by a method which allowed simultaneous measurement of the cross-sectional area. In healthy women a pressure range of 25-140 cm H2O was recorded at one urethral site as a response to the circumstances under which the measurement was performed. The pressures obtained were related to the degree of urethral distension and to the time after the change in distension. Measuring urethral pressure at one specific degree of distension results in one specific pressure value according to the dimensions of the measuring probe. However, this specific pressure value cannot be considered to supply more information on urethral sphincter function than any other pressures included in a range which can be obtained by changing the circumstances under which the measurement are carried out. More provocative methods of pressure measurement which simulate some of the physiological conditions of the urethra may provide more information on sphincter efficiency.

Adult↗
PubMed1992

Pressure response to rapid dilation of resting urethra in healthy women.

Rapid urethral dilations were performed by a balloon mounted on a double-tip transducer catheter for simultaneous measurement of pressure in urethra and bladder. The cross sectional area of the urethra was measured according to the field gradient principle. Pressure and cross sectional area were recorded synchronously. The response of the female urethra to rapid dilation is a typical stress relaxation effect with a pressure peak followed by a pressure decay over a few seconds. The peak pressure response represents the bladder pressure required in producing a corresponding urethral dilation by the ingression of urine. The increase in pressure response was statistically significant by increasing rate as well as size of dilation. The method enables experimental simulation of stress urinary incontinence in vivo which may bring further insight into the physiology of the urethral closure function and the pathophysiology of stress incontinence. For comparative studies rapid dilation should be performed under standardized circumstances.

Adult↗
PubMed1992

Initial urethral pressure increase during stress episodes in genuine stress incontinent women.

The urethral and bladder pressure increments registered during a cough were investigated in 30 woman with genuine stress incontinence (GSI) and compared with those from 30 previously investigated healthy women. The pressures were measured by means of a double microtip transducer catheter with the bladder sensor uncovered and the urethral sensor covered with a water-filled rubber cylinder and placed at the bladder neck, midurethrally, or distally in the urethra. In GSI women the pressure increment preceding the pressure spike produced by coughing was significantly higher in the bladder compared with the urethra, and the pressure increment seemed to be initiated in the bladder and all along the urethra simultaneously. In healthy women the pressure increment preceding a pressure spike was significantly higher in the midurethra compared with the bladder and it seemed to be initiated in the midurethra. These findings seem to reflect a defective active closure mechanism in GSI which may be a contributing factor in its pathogenesis.

Adult↗
PubMed1992

The effect of alpha-adrenoceptor stimulation and blockade on the static urethral sphincter function in healthy females.

The influence of noradrenaline and prazosin on the urethral closure function was evaluated in 10 healthy female volunteers. Measurements of pressure at varying cross sectional areas were carried out at the bladder neck, in the high pressure zone, and in the distal urethra. Prazosin reduced the static pressure, predominantly in the midportion of the urethra, whereas noradrenaline caused no significant pressure change. The urethral resistance to dilatation and the hysteresis were unaffected by the two agents. It is suggested that the response to prazosin is related to decreased activity of the urethral smooth as well as of the striated muscles, the latter as a result of a reduced somatomotor output from the central nervous system.

Adult↗
PubMed1991

[The significance of brain death as a criterion for renal transplantation. Status after 9 months].

The effect of introduction of the brain-death criterion in Denmark on the course of cadaver kidney transplantation was evaluated by comparing the course of 31 consecutive patients transplanted after introduction of brain-death criterion with the course of a similar consecutive group of patients transplanted just before the new death criterion. The consequences of the new death criterion were significantly earlier onset of graft function, diminished need for posttransplant dialyses, reduced need for immunosuppressive treatment with Minnesota-antilymphocytglobulin and briefer hospital stays. The easier postoperative course had great psychological effects for the patients and the staff, and the cost of each transplantation was estimated to be reduced by at least 50,000 DKr per patient (approximately 5,000 pounds).

Brain Death↗
PubMed1991

How to measure urethral elastance in a simple way. Elastance: definition, determination and implications.

The elastance of a biological tube describes the resistance of the latter to dilatation. It is defined as dP/dV, where dP is the pressure increase caused by the volume increase dV. Elastance is the reciprocal of compliance. Elastance in the female urethra can be estimated from the slope of the regression line of related values of pressure and cross-sectional area. In the present study, urethral elastance was calculated by measurement of the related pressures and cross-sectional areas during stepwise dilatation by a balloon and by determination of the pressure at which inflow through side holes in catheters with increasing diameters began. There was no difference between the elastance values obtained by the two methods. Due to the linear correlation found between pressure and cross-sectional area we conclude that urethral elastance can be estimated from measurements of urethral pressure at two or more related cross-sectional areas by a simple technique using e.g., 8F, 14F, and 20F catheters.

Adult↗
PubMed1991

Method for evaluation of the urethral closure mechanism in women during standardised changes of cross-sectional area.

A method for evaluation of the closure mechanism in the female urethra during forced opening has been developed and tested. The cross-sectional area (CA) of the tube and the intraluminal pressure were measured simultaneously by a specially designed balloon catheter. The method enables induction of standardised changes of CA at different rates. Applied in the female urethra the induction results in a distinct pressure response which increases with increasing rate of change of CA as well as size of the induction. The inflation of the balloon simulates a forced opening of the urethra and hence leakage. Obviously, urinary incontinence takes place at forced opening of the urethra. Accordingly, this novel method can give important information on the pathophysiology of stress urinary incontinence in particular and the physiology of sphincter functions in general.

Catheterization↗
PubMed1991

Urethral pressure and power generation during coughing and voluntary contraction of the pelvic floor in healthy females.

A probe which permits continuous measurement of the related values of pressure and cross-sectional area in the female urethra was used to provide a quantitative description of the adjunctive occlusive forces in terms of pressure and power (mWatt) generation. Measurements were carried out at the bladder neck, midurethrally and distally in the urethra in 30 healthy women during coughing and squeezing. Statistically significant variations were found in pressure and power generation between the 3 sites of measurement both during coughing and squeezing. Power generation and the pressure increase were significantly greater during coughing than during squeezing along the entire length of the urethra. The presence of a dynamic active closure mechanism was demonstrated at the bladder neck in addition to that located midurethrally. This bladder neck mechanism is thought to be due to the vagino-levator sling system (the urethral supports).

Adult↗
PubMed1991

Erectile dysfunction following direct vision internal urethrotomy.

A total of 104 evaluable patients 20-90 years old treated by direct vision internal urethrotomy a.m. Sachse for urethral strictures reported retrospectively via a questionnaire their sexual potency before and after internal urethrotomy. Eleven patients (10.6%) experienced partial or total erectile dysfunction following the operation, most of whom had distal and long strictures. Eight were evaluated for impotence and on grounds of a comprehensive history, physical examination, penile Doppler investigations, and papaverine tests it was concluded that 3 patients might have achieved an abnormal communication between the corpus cavernosum and corpus spongiosum. In two of the patients cavernosographies were carried out and in one total opacification of the corpus spongiosum was demonstrated, but the exact location of the leak could not be pinpointed, and surgical treatment therefore not rendered feasible. Possible factors in the development of erectile dysfunction following internal urethrotomy are analyzed.

Adult↗
PubMed1991

Liposarcoma of the spermatic cord. Case report.

We report a case of a 78-year-old man with liposarcoma of the spermatic cord. This rare tumour, which is slow growing and tends to recur locally, must be considered in the differential diagnosis of solid tumours between the testis and the internal ring. The surgical treatment is radical orchiectomy with wide local excision and high ligation of the spermatic cord. Retroperitoneal lymph node dissection is debatable and the value of chemo- and radiotherapy is uncertain.

Aged↗