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Biomedical subjects

A Mattiasson

Publications and source records attributed to A Mattiasson.

At least 19 recordsLinked to original sources
PubMed2000

Cell-kill modeling of microwave thermotherapy for treatment of benign prostatic hyperplasia.

PURPOSE: We investigated whether cell-kill modelling could be used as a mean for predicting the outcome of microwave thermotherapy for benign prostate hyperplasia (BPH). METHODS: The two models--Henriques' damage integral and Jung's compartment model--were implemented in a computer program. Real treatment data for 22 patients with BPH who were in chronic retention were used as input, including measured intraprostatic temperatures and microwave power. To test if modelling gives results that are consistent with actual observations, comparison with transrectal ultrasound (TRUS) measurements of the prostate volume before and after treatment was made. The sensitivity of the computer model for variations in the heat cytotoxicity and the temperature probe location in the adenoma was also tested. RESULTS: The average TRUS volume reduction 3 months after treatment was 26 cc, whereas the corresponding cell kill calculation was 27 cc. The computer model appears to be rather insensitive to minor uncertainties in heat sensitivity and location of the intraprostatic reference temperature sensors. CONCLUSION: Cell-kill modelling appears to give results that are consistent with actual observations. The coagulated tissue volume is calculated in real time during the treatment, thereby providing an immediate prediction of the treatment outcome. By using cell-kill modelling, the endpoint of a treatment can be set individually; e.g., when a certain volume reduction has been achieved.

Cell Death↗
PubMed2000

Aspects on transurethral microwave thermotherapy of benign prostatic hyperplasia.

The underlying principle behind new minimal invasive procedures, such as microwave thermotherapy, is to coagulate the prostatic adenomatous tissue by means of heat. This article describes the action of heat on tissue and identifies areas of concern during treatment. The extent of the necrosis during treatment is governed by two physical variables: the intraprostatic temperature and the duration of the heat exposure. The prostatic blood flow is a key factor for the outcome of microwave treatment because it acts as a coolant and may effectively sink the temperature in the treatment area. Blood flow can vary substantially between patients and may change significantly during treatment. By measuring the intraprostatic temperature and varying the microwave power accordingly, it is possible to compensate for the large variations in prostatic blood flow and obtain consistent treatment.

Humans↗
PubMed1999

Cortical magnetic stimulation in patients with genuine stress incontinence: correlation with results of pelvic floor exercises.

Pelvic floor training is an established conservative method of treatment in patients with genuine stress incontinence. It is not known why only a proportion of patients benefit from this form of treatment, while others with a comparable degree of incontinence do not. Since muscle awareness is of vital importance in pelvic floor training, we decided to investigate whether differences in outcome might be explained by differences in cortical control of the pelvic floor muscles. The function in the total motor pathway to the pelvic floor muscles was examined with cortical magnetic stimulation and circumvaginal EMG recording. Since lesions of the peripheral motor pathway have been demonstrated in patients with genuine stress incontinence, possible differences at this level were investigated by means of terminal pudendal motor latencies, using electrical nerve stimulation and anal recording EMG. We found that patients who succeeded with pelvic floor exercises for genuine stress incontinence had a significantly higher probability of response to cortical magnetic stimulation and significantly larger response amplitudes than the patients who did not benefit from training. The findings in the latter group did not differ from those of a healthy control group. No differences between the groups were found in the terminal pudendal motor latencies. We conclude that women with genuine stress urinary incontinence, successfully alleviated by a physiotherapeutic training program, have a higher degree of corticofugal control of their perineal muscles than women who do not succeed with the same treatment program and healthy controls. Neurourol. Urodynam. 18:437-445, 1999.

Adult↗
PubMed1999

Female stress, urge, and mixed urinary incontinence are associated with a chronic and progressive pelvic floor/vaginal neuromuscular disorder: An investigation of 317 healthy and incontinent women using vaginal surface electromyography.

Reduction of the maximum vaginal surface electromyography (EMG) activity has previously been demonstrated in women with stress, urge, and mixed incontinence in comparison with healthy volunteers [Gunnarsson and Mattiasson, Scand J Urol Nephol 157:89-95, 1994]. The present study was performed to investigate if these EMG changes are age dependent and whether healthy parous women in general might show an age-related decrease of vaginal and pelvic neuromuscular activity. A total of 317 women, 144 with urinary incontinence and 173 healthy volunteers, 20 to 76 years of age, were investigated. The maximum EMG activity during repeated short contractions (2 s) was measured. We found that parous women who have maintained continence through the years had a normal pelvic floor function as estimated with vaginal surface EMG. In contrast, all three groups of incontinent women showed a successive decrease of the EMG activity with increasing age. This difference was highly significant (P < 0.001) in women above the age of 50. No significant differences could be seen between groups when stress, urge, and mixed incontinent women were compared. Even though any convincing correlation between the amount of urinary leakage and the reduction of EMG activity was not found, we conclude that a chronic and progressive deterioration of the pelvic-vaginal neuromuscular function occurs in women who develop urinary incontinence. The results support the view that a common pathophysiological mechanism in patients with stress, urge, and mixed incontinence might exist. The findings might help to establish a new perspective for the understanding of the pathophysiology, diagnosis, treatment, and prevention of female incontinence. Neurourol. Urodynam. 18:613-621, 1999.

Adult↗
PubMed1998

Cost-effectiveness of new treatments for overactive bladder: the example of tolterodine, a new muscarinic agent: a Markov model.

Economic analyses of interventions for chronic diseases require evaluations over a long timeframe to illustrate the benefits and costs of treatments. Clinical trials are generally short and carried out in strictly controlled conditions. They are therefore of limited value for economic evaluation aimed at facilitating decisions about resource allocation. The objective of this study was to develop a simulation model that allows integration of data from different sources to calculate the incremental cost-effectiveness and cost-utility of new treatments for overactive bladder. The model compares tolterodine, a new treatment that aims at alleviating symptoms and improving patients' quality of life, to no treatment. Simulations for Sweden are presented as an example. The Markov model combines clinical, observational, and economic data. Markov states are defined based on severity of symptoms of overactive bladder (frequency of voids and leaks). Specific costs for drug treatment and use of sanitary protections as well as utilities are assigned for each state. The effectiveness of tolterodine is based on controlled clinical trials and open long-term extensions of these trials. Outcome is measured as quality-adjusted life years (QALYs) and as the number of months spent in a state with no or very limited symptoms. During the course of 1 year, patients treated with tolterodine spend more time in states with no or limited symptoms compared to those receiving no treatment. Tolterodine-treated patients having a better quality of life during the year. The mean utility of the treated cohort is 0.70, compared to 0.67 in the no-treatment cohort, which is equivalent to the entire cohort moving by one level to a state with less severe symptoms. Mean total costs per patient in the tolterodine arm are SEK8,595 (US $1,131; 1 US$ = 7.6 SEK) compared to SEK3,286 (US$432) in the no-treatment arm. The extra cost due to tolterodine is SEK380 (US$50) per month, which falls within the range of monthly amounts that patients were willing to pay out of pocket for a 25 or 50% improvement of their symptoms in a previous study. The cost for pads is reduced by 23%. The marginal cost per QALY gained with tolterodine is estimated at SEK213,000 (US$28,000). Based on this simulation model, it appears that treatment of overactive bladder with a well-tolerated pharmacological treatment such as tolterodine is cost-effective.

Benzhydryl Compounds↗
PubMed1998

Shortening velocity is different in longitudinal and circular muscle layers of the rabbit urethra.

The aim of the study was to investigate whether the functional difference between circular and longitudinal muscles in the female rabbit urethra is reflected in their shortening properties and lactate dehydrogenase (LDH) activity. For mechanical experiments the preparations were chemically skinned to avoid influence of membrane-related mechanisms and to enable maximal activation. Force velocity relations and the maximal shortening velocity (v(max)) were determined using the isotonic quick-release method. The v(max) was three times higher in longitudinal muscle. LDH isoform pattern was determined on agarose gels. The M-subunit, favourable for lactate formation, constituted 70% of the total in both types of muscle. There was no difference in the LDH isoform pattern despite the marked difference in v(max). We conclude that the difference in v(max) reflects differences in the contractile machinery itself. These mechanical characteristics are advantageous for the role of the circular as a tonic muscle contracting during bladder filling, and the longitudinal as a phasic muscle active in opening up the urethra during micturition.

Animals↗
PubMed1998

Optimizing transurethral microwave thermotherapy: a model for studying power, blood flow, temperature variations and tissue destruction.

OBJECTIVE: To examine the role of microwave power and blood flow on temperature variations and tissue destruction in the prostate, using a theoretical model of transurethral microwave thermotherapy (TUMT), and thus compare fixed-energy TUMT with no intraprostatic temperature monitoring (constant microwave power applied over a fixed period) with 'feedback' TUMT in which the microwave power is adjusted according to the monitored intraprostatic temperature. MATERIALS AND METHODS: The temperature distribution in the prostate was modelled for a typical TUMT catheter at various blood flow rates. The volume of tissue destroyed was simultaneously calculated from cell survival data after thermal exposure. The calculated quantity of tissue destroyed at the different microwave power levels and blood flow rates was used to describe qualitatively the simulated treatments. RESULTS: Treatment monitoring and consistency were better during feedback TUMT than fixed-energy TUMT, in that the former compensated for variations in blood flow rate. The modelled values agreed with observations during real TUMT. CONCLUSIONS: Blood flow rate is a key factor in the outcome of TUMT. Only by measuring intraprostatic temperature is it possible to compensate for the large variations in prostatic blood flow and obtain consistent treatment results. Repeated interruptions prompted by high rectal temperatures should be minimized and preferably avoided, as the quantity of tissue destroyed is then greatly reduced, and in extreme cases the treatment is totally ineffective.

Blood Flow Velocity↗
PubMed1998

Tolterodine, a new antimuscarinic agent: as effective but better tolerated than oxybutynin in patients with an overactive bladder.

OBJECTIVE: To compare the efficacy and tolerability of tolterodine with that of oxybutynin in patients with an overactive bladder. PATIENTS AND METHODS: A randomized, double-blind, placebo-controlled, parallel group, multinational phase-III study was conducted in urology and gynaecology clinics in the UK, Republic of Ireland and Sweden. The study enrolled 293 patients with urodynamically confirmed bladder overactivity, increased frequency of micturition (> or = micturitions/24 h) and symptoms of urgency and/or urge incontinence (> or = 1 episode/24 h). Patients received either tolterodine (2 mg twice daily) or oxybutynin (5 mg three times daily) or placebo. Doses could be reduced, to prevent withdrawal, to 1 mg or 2.5 mg, respectively. The main outcome measures were the mean change from baseline in frequency of micturition/24 h, the number of incontinent episodes/24 h and volume voided per micturition. RESULTS: After 12 weeks' treatment, the mean frequency of micturition decreased by 21% and 19.5% in those receiving tolterodine (n = 118) and oxybutynin (n = 118), respectively, and by 10.5% in those on placebo (n = 57). Among those with urge incontinence at baseline (75% of patients), the mean number of incontinent episodes decreased by 47%, 71% and 19%, respectively, in those receiving tolterodine, oxybutynin and placebo. The effect of tolterodine and oxybutynin on these two micturition variables was statistically equivalent. There was also a comparable increase in mean volume voided per micturition in the tolterodine (27%) and oxybutynin groups (31%), compared with 7% in the placebo group. Dry mouth was the most common adverse event and was reported with greater frequency and intensity among patients receiving oxybutynin than among those receiving either tolterodine or placebo. In the oxybutynin group, more patients also withdrew because of adverse events and a greater proportion required dose reduction as a result of adverse events. Despite dose reduction, the frequency of adverse events and the intensity of dry mouth remained higher among those receiving oxybutynin (2.5 mg three times daily) than in patients who remained on tolterodine 2 mg twice daily. CONCLUSION: Tolterodine 2 mg twice daily is effective and well tolerated in the treatment of bladder overactivity. Tolterodine was better tolerated than oxybutynin, particularly with respect to the frequency and intensity of dry mouth, but had comparable clinical efficacy. The superior tolerability of tolterodine therefore allows more patients to remain on effective therapy than the current most commonly prescribed agent for the treatment of the overactive bladder.

Adult↗
PubMed1997

Effects of spinal alpha 1-adrenoceptor antagonism on bladder activity induced by apomorphine in conscious rats with and without bladder outlet obstruction.

To test the hypothesis that the spinal control of micturition involves alpha 1-adrenoceptors, the urodynamic effects of intrathecal and intraarterial alpha 1-adrenoceptor blockade on apomorphine-induced bladder activity in rats were studied. Continuous cystometry was performed in conscious female Sprague-Dawley rats with and without bladder outflow obstruction. In normal rats, subcutaneous apomorphine, 30 micrograms/kg, induced bladder activity that was abolished or attenuated by the alpha 1-adrenoceptor antagonists indoramin and doxazosin given intrathecally or intra-arterially. In rats with outlet obstruction, apomorphine 30 micrograms/kg caused no change in cystometric parameters. However, at a dose of 100 micrograms/kg the drug induced bladder activity, which was attenuated by intrathecal indoramin or doxazosin. These results suggest that the bladder activity evoked by apomorphine-stimulation of bulbospinal pathways can be influenced by alpha 1-adrenoceptors at the spinal and peripheral levels, both in normal rats and in rats with bladder hypertrophy secondary to outlet obstruction.

Adrenergic alpha-Antagonists↗
PubMed1997

Stimulation of bladder activity by volume, L-dopa and capsaicin in normal conscious rats--effects of spinal alpha 1-adrenoceptor blockade.

To study possible differences in alpha 1-adrenoceptor involvement in the spinal mechanisms mediating bladder activity induced by volume (bladder filling), central (L-dopa), and peripheral (capsaicin) stimulation, we investigated if these types of bladder activity were modified by intrathecal (i.t.) or intra-arterial (i.a.) administration of the alpha 1-adrenoceptor antagonist, indoramin. Indoramin is selective for the alpha 1A-adrenoceptor subtype, whereas most clinically used alpha 1-adrenoceptor antagonists, including doxazosin, have no subtype selectivity. The drug effects were studied by continuous cystometry in normal, conscious rats and rats with bladder activity evoked by intraperitoneal L-dopa (50 mg/kg after carbidopa pretreatment), or by intravesical capsaicin (30 microM). I.t. indoramin (50 nmol) significantly decreased micturition pressure, and increased bladder capacity and micturition volume. Dribbling incontinence due to urinary retention was observed in one of ten rats. L-dopa-stimulated bladder overactivity was significantly attenuated by i.t. or i.a. indoramin (50 nmol). Similar effects of i.t. and i.a. doxazosin (50 nmol) have been reported previously. Intravesical capsaicin (30 microM) caused bladder activity, which was attenuated by i.t. indoramin (50 nmol), but not by i.t. doxazosin (50 nmol). I.a. indoramin did not reduce capsaicin-induced bladder activity; doxazosin was moderately effective. The results suggest that the bulbospinal micturition reflex evoked by bladder filling and L-dopa involves a descending pathway where transmission is partly mediated by spinal alpha 1-adrenoceptors. Bladder overactivity evoked by intravesical capsaicin, which elicits a vesicospinal-vesical reflex, was not affected by i.t. doxazosin in a dose that attenuates activity mediated through the bulbo-spinal pathway. This suggests less involvement of spinal alpha 1-adrenoceptors in the vesico-spinal-vesical than in the bulbo-spinal voiding reflex.

Adrenergic alpha-1 Receptor Antagonists↗