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Biomedical subjects

T Janssen

Publications and source records attributed to T Janssen.

At least 55 records · Page 3Linked to original sources
PubMed1994

Deep dorsal vein arterialization in vascular impotence.

33 patients underwent a penile deep dorsal vein arterialization (DDVA) (11 venous leak, 8 pure arteriogenic impotence, 14 mixed arterial and venous impotence). The mean follow-up was 12 months. Surgery was considered successful when the patients had permeable anastomosis and were able to achieve satisfactory erections resulting in normal intercourse. 92% of the patients with venous leak, 62.5% of those with arteriogenic impotence and 58% with mixed lesions had a successful results. Due to antithrombotic therapy, there was no graft occlusion. Glans hypervascularity occurred in 3 patients and was treated by arterial banding. The role of DDVA in vascular impotence and its functional mechanism are discussed.

Adult↗
PubMed1994

[Prostate-specific antigen: an evaluation 15 years after its discovery].

Fifteen years after its discovery, PSA is the most useful marker for prostate cancer. We summarize the biomolecular characteristics of PSA and the various PSA assays. We define its role in the diagnosis of prostate cancer, and we discuss its value in the monitoring of treated patients.

Humans↗
PubMed1994

[Laparoscopic surgery in urology: current status and trends in 1993].

Laparoscopic surgery in Urology is in a testing and development phase. The technique is currently used by some urologists to evaluate nonpalpable testes and to perform varicocelectomy or pelvic lymphadenectomy. Other standard open surgical procedures are experimentally being performed with the laparoscope. Owing to technologic advances laparoscopic surgery might become a part of routine urological care. We review the current impact of laparoscopy on Urology, we emphasize the advantages but also the risks of this new approach, and we discuss the benefit of these surgical procedures..

Adrenal Glands↗
PubMed1994

[Retroperitoneal fibrosis due to barium].

The authors report two cases of retroperitoneal fibrosis secondary to rectal perforation occurring during barium enema. In view of the variable interval between the radiological accident and the urological complications, a long patient follow-up is recommended. If ureteric obstruction occurs, ureteric catheterisation is a temporary alternative, but surgery is the treatment of choice. When ureterolysis cannot be performed, the authors propose ureteroileoplasty to restore continuity of the urinary tract.

Aged↗
PubMed1994

[Laparoscopic treatment of vesico-ureteral reflux in the pig. Preliminary report].

Laparoscopic urological surgery is currently in a phase of development. In order to evaluate the possibility of treating vesicoureteric reflux by laparoscopy, we performed an elongation of the submucosal ureteric tract via an extravesical approach (Lich-Gregoir) in 4 pigs. After creating a pneumoperitoneum, 4 trocars were introduced into the abdominal cavity. The peritoneum was incised at the level of the iliac vessels and the ureter was released at its middle portion as far as the ureterovesical junction. After coagulation, the detrusor was then incised proximally in relation to the ureterovesical junction, revealing 3 to 4 cm of vesical mucosa. The ureter was buried in the muscular groove, the edges of which were brought together by means of 6 metal staples. In 3 pigs, the bladder and ureter were immediately removed by laparotomy. On macroscopic examination, the staples correctly approximated the muscle layer without transfixing the bladder mucosa or ureter. The patency of the ureter was assessed with a probe. The submucosal tract was sufficiently large, preventing any ureteric compression. In 1 pig, the ureteric meati were incised endoscopically to create reflux. After laparoscopic elongation of the submucosal tract on one side, only the untreated ureter continued to reflux. Correction of vesicoureteric reflux is technically feasible in the pig. Longer studies are necessary before considering the application of this technique to man.

Animals↗
PubMed1993

[Microsurgical treatment of impotence of vascular origin].

Impotence of vascular origin may be due to a defect of the arterial blood supply, a cavernous venous leak or a combination of the two phenomena. Several microsurgical techniques have been proposed to restore physiological erectile function, without the use of intracavernous injections of vasoactive drugs or implantation of penile prostheses. We have used this type of surgery in motivated and selected patients for more than 15 years (72 patients treated, 57 patients evaluated after surgery). In patients with impotence of arterial origin, we perform a Michal II arterio-arterial revascularisation in the case of limited proximal or distal lesions with preservation of one of the two dorsal arteries, (13 patients) and arterialisation of the deep dorsal vein of the penis in the case of diffuse distal lesions (8 patients). 62% of positive results were obtained with both forms of revascularisation with a mean follow-up of 22 months. In patients with impotence of venous origin (11 patients), we perform arterialisation of the deep dorsal vein of the penis, with 92% of positive results with a mean follow-up of 12 months. In patients with impotence of arterial and venous origin (25 patients), we carry out a Michal II revascularisation and ligation of the dorsal vein or arterialisation of the dorsal vein achieves 64% and 58% of positive results with a mean follow-up of 12 months and 5 months, respectively. In the light of these results, the authors try to define the place of vascular microsurgery in the treatment of impotence.

Adult↗
PubMed1991

Effect of propelling surface size on the mechanics and energetics of front crawl swimming.

In swimming the propulsive force is generated by giving a velocity change to masses of water. In this process energy is transferred from the swimmer to the water, which cannot be used to propel the swimmer. Theoretical considerations indicated that an increase of the propelling surface size should lead to a reduced loss of energy to the water. Thus, in this study, the effect of artificially enlarging the propelling surface of the hand was examined. The effect was examined in terms of the propelling efficiency during front crawl swimming using the arms alone. The legs were floated with a small buoy as previously described (Toussaint et al., J. appl. Physiol. 65, 2506-2512, 1988a). In ten competitive swimmers (six male, four female) the rate of energy expenditure (power input, Pi), power output (Po), work per stroke cycle (As), distance per stroke cycle (d), work per unit distance (Ad), and propelling efficiency (ep) were determined at various swimming speeds once with and once swimming without paddles. At the same average velocity the effect of swimming with paddles was to reduce Pi, Po, and Ad by 6, 7.6, and 7.5% respectively, but to increase ep and As by 7.8 and 7%. The increase in distance per stroke cycle and the decrease in stroke cycle frequency matched the predicted values based on the theoretical considerations in which the actual increase in propelling surface size was taken into account.

Arm↗
PubMed1991

Infrarenal aortic occlusion in the rabbit to assess the effect of flunarizine in the prevention of ischemic spinal cord injury.

Infrarenal aortic occlusion in rabbits to produce paraplegia is possible in large series and can be achieved without any side-effects of anesthetic drugs. This model was tested for its suitability to investigate the use of calcium-channel blockers, which potentially reduce or prevent ischemic spinal cord damage. In a pilot study 26 rabbits were treated with 0.1 mg/kg Flunarizine i.v. prior to occlusion and 38 animals served as control. Groups were compared where the aorta was occluded for 10, 15, 20, 25 or 30 min. No reduction of paraplegia in the Flunarizine groups was observed, apart from in the 15-min occlusion subset: here the number of unaffected animals was significantly greater (p less than 0.05). At histopathological examination the number of ischemic spinal cord segments was reduced (p less than 0.03). It is concluded that Flunarizine could not reduce the cellular damage of the spinal-cord due to complete and global ischemia after an aortic occlusion interval exceeding 15 min. The narrow interval between potential recovery (15 min) and definite paraplegia (20 min) makes this rabbit paraplegia model less appropriate for testing of calcium-channel blockers which are presumed to have a moderate effect on the reduction of spinal cord ischemia.

Animals↗
PubMed1991

[Is the duplicity theory of the hair cells still valid today?].

The "Duplizitätstheorie" of Meyer zum Gottesberge (1948) states that signal processing takes place at low sound intensities on the nerve fibers of the outer hair cells, whereas at high sound intensities on the nerve fibers of the inner hair cells. The discovery of oto-acoustic emissions by Kemp (1978) makes a modification of the "Duplizitätstheorie" necessary. The outer hair cells are supposed to be motor-drives final control elements to enhance the sensitivity of inner hair cells. Thus outer hair cells do not serve for the direct transmission of information in the sense of neural coding. Signal processing takes place at all intensities exclusively on the nerve fibers of the inner hair cells.

Acoustic Stimulation↗
PubMed1989

[Correlation of the latency shift and brain stem potentials in basocochlear hearing loss and the time course of the click stimulus-induced evoked wave in the cochlea].

Frequency-specific information on high tone loss in the inner ear can, and if so only indirectly, be obtained from changes in latency of the click-evoked brain stem potential (ABR). The relationship between latency increases of the Jewett-wave-V in basocochlear hearing loss and the time course of the travelling wave on the basilar membrane will be presented. The latency increases of basocochlear hearing loss at 2 kHz, 1 kHz and 500 Hz correspond to both the computer-simulated time course of the travelling wave and to those of the derived responses. From a pathophysiological standpoint, receptor cells in basocochlear hearing loss are not functional, beginning at the oval window, so that, dependent on the degree of inactivity, a delay corresponding to that of the time course of the travelling wave passes until active hair cells are reached and action potentials released that produce, when summed up a potential of delayed latency.

Acoustic Stimulation↗
PubMed1989

[Hypospadias: surgical aspects and personal experience].

In the last eight year period, a series of 102 hypospadias reconstruction performed in our institution were reviewed. 50% presented with marked degree of chordee. Four types of repair where used: MAGPI (n degree 18), Mathieu (n degree 41), Duckett (n degree 28), two stage repair (Duplay) (n degree 12), other procedures (n degree 3). Overall complication rate was 18% and was related to major procedure and difficult technical situations. It never compromised the final outcome of the procedure. The relatively high complication rate mentioned in the literature and in our series emphasizes that hypospadias surgery has to be done by well trained surgeons in this field.

Clinical Competence↗
PubMed1988

Click ABR intensity-latency characteristics in diagnosing conductive and cochlear hearing losses.

A schematic description of the correlation between various pathologies of hearing impairments and the behavior of auditory brainstem responses (ABR) is presented. Conductive pathology and high-frequency cochlear hearing losses prolong wave component latency due to energy loss and hair cell dysfunction. In cases of flat cochlear hearing loss latency is not affected. Prolonged interwave latencies between wave I and wave V indicate eight nerve and brainstem disorders. An algorithm was developed in the form of a flow chart for locating various malfunctions. Fields of wave V intensity-latency functions were designed for the faster detection and more precise evaluation of conductive and cochlear hearing losses.

Algorithms↗
PubMed1988

[Response latency characteristics for ENT medical assessment of auditory brain stem evoked response].

A schematic description of the correlation between the various types of hearing disorders and the behaviour of auditory brain stem responses (ABR) is presented. Conductive pathology and high-frequency cochlear hearing loss prolong wave component latency due to energy loss and hair cell dysfunction. Latency is not affected in flat cochlear hearing loss. Prolonged interwave latencies between wave I and wave V indicate eighth nerve and brain stem disorders. An algorithm in the form of a flow chart was developed for location of the malfunction. Families of characteristics of wave V intensity-latency functions were designed for faster detection and more precise evaluation of conductive and cochlear hearing losses.

Audiometry, Evoked Response↗
PubMed1988

[The significance of the family as primary caregiver for the aged in need of assistance].

This study focuses on the experiences of the primary care-giver of somatically impaired older people and intends to get a better understanding of the social conditions, difficulties and limitations of family care. Data come from qualitative in depth interviews with 52 primary care-givers: 24 spouses, 21 children (mostly daughters) and seven other women. In this article special attention is given to the importance of other people (mostly members of the family) to the primary care-giver. Fifty % of the primary care-givers experienced their situation as not so burdensome, 25% as rather and also 25% as very burdensome. Support turns out to be very important for the primary care-giver but lots of support does not always prevent a situation from becoming very burdensome. Three kinds of stress have been distinguished: care-stress, relation-stress and network-stress. Particularly network-stress turns out to be indicative for very burdensome situations. Pre-eminently one is experiencing this kind of stress if one is also experiencing care- and relation-stress. In spite of much stress and feelings of burden however, people tend to continue with caring. A strong sense of duty plays a mayor part here. Finally, the current political trend to effect a shift to more informal care, is critically evaluated in the light of the results of the research.

Aged↗
PubMed1988

[Effect of cochlear processes in generating Jewett IV and V brain stem potential components].

Polarity of the stimulus influences latency, amplitude and waveform of the human auditory brainstem response (ABR). One clear feature is the splitting of the wave complex JIV and JV in separate peaks following rarefaction stimulation. ABR was recorded using high-pass filtering to mask the basilar membrane partially to establish whether and to what extent basal hair cells contribute to waves IV and V. Wave IV disappeared in response to rarefaction stimuli with masking of the basal region. In contrast, wave V appeared with reduced amplitude and delayed latency in response to condensation stimuli. A model was developed to determine the motion of the basilar membrane and the distribution over time of the action potential on the auditory nerve fibers following rarefaction and condensation stimuli. The rarefaction stimulus produces a bifid and the condensation stimulus only a single-peaked contribution. It is suggested that the splitting of the wave complex IV and V may be traced to mechanical processing in the cochlea.

Auditory Pathways↗