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Biomedical subjects

T Janssen

Publications and source records attributed to T Janssen.

At least 19 recordsLinked to original sources
PubMed1995

Influence of dihydrotestosterone, epidermal growth factor, and basic fibroblast growth factor on the cell kinetics of the PC3, DU145, and LNCaP prostatic cancer cell lines: relationship with DNA ploidy level.

The cell kinetics (percentage of cells in the S+G2 phases of the cell cycle) and the DNA ploidy levels (nuclear DNA content) were determined in 108 samples each of the PC3, DU145, and LNCaP prostate cancer models. This was carried out by means of the digital cell image analysis of Feulgen-stained nuclei. Two to three hundred cell nuclei were analyzed for each of the 324 samples under study. The three cell lines were submitted to experimental conditions including the addition of dihydrotestosterone (DHT), epidermal growth factor (EGF), and basic fibroblast growth factor (bFGF), either alone or in combination, to the culture media. The results show that under the present culture conditions, the PC3 cell line was DHT-, EGF- and bFGF-insensitive. In contrast to what is generally reported in the literature, the DU145 cell line was DHT- and EGF-sensitive under the present culture conditions, but bFGF-insensitive. The LNCaP cell line was DHT-sensitive, but EGF- and bFGF-insensitive. While mainly tetraploid, the three cell lines nevertheless exhibited a significant level of heterogeneity in their nuclear DNA content distributions. Indeed, the proportions of non-tetraploid (diploid, hyperdiploid, triploid, hypertriploid, hypertetraploid, polymorphic) DNA histograms were 14% in the PC3, 16% in the DU145, and 29% in the LNCaP cell lines. These results suggest that the DNA ploidy level would not influence the hormone sensitivity level in the cell lines since they had significantly distinct hormone sensitivity profiles while remaining mainly tetraploid.

Cell Division↗
PubMed1995

Suppression tuning characteristics of the 2 f1-f2 distortion-product otoacoustic emission in humans.

The suppression tuning properties of the 2 f1-f2 distortion-product otoacoustic emission (DPOAE) were measured in 16 ears of normally hearing human subjects. DPOAE were elicited by fixed, low-level primary tones in four frequency regions with the second primary tone frequency f2 at 1, 2, 4, and 6 kHz. For various suppressor frequencies, suppression of the DPOAE was measured as a function of the suppressor tone level, enabling the assessment of the threshold and the growth of suppression. Depending on the distance of the suppressor tone to f2, there were marked differences in the suppression behavior of different suppressor frequencies. The threshold of suppression was minimal slightly above f2 and hardly increased with increasing frequency, but increased continuously with decreasing suppressor frequency. The growth of suppression, however, did not systematically change below f2, but decreased rapidly above f2. Both changes resulted in asymmetrical, V-shaped suppression tuning curves. They were sharply tuned to a frequency slightly above f2, with Q10 dB values up to 7.87. This is consistent with the assumption that the main source of the DPOAE is at the f2 site. In some cases, the DPOAE was particularly sensitive to suppressor tones near the DPOAE frequency. In one individual case, facilitation was found for corresponding frequency-level ranges of the suppressor tone. This may suggest a secondary emission source at the distortion product place.

Acoustic Stimulation↗
PubMed1995

Tumour-associated trypsin inhibitor and renal cell carcinoma.

In the absence of a specific marker for renal cell carcinoma (RCC), we evaluated the tumour-associated trypsin inhibitor (TATI) in patients with RCC. Between November 1990 and November 1993, 63 patients with RCC and 23 patients with benign renal disease underwent a competitive radioimmunoassay of TATI. The cutoff value was defined on a series of serum samples of 96 healthy subjects (normal n < 20 micrograms/l, then 25 micrograms/l after April 1993). We related the value of TATI to the tumour stage and compared the sensitivities of TATI and other markers (CEA, CA 15-3, CA 125, CA 19-9, ferritin). In 24 patients the TATI assay was repeated 3-12 months after radical nephrectomy. 15 patients with benign disease had a normal value of TATI (specificity: 65%). 44 of the 63 patients had a value of TATI above the cutoff point (sensitivity: 69%). Sensitivities of CEA, CA 15-3, CA 125, CA 19-9 and ferritin were 5, 10, 13, 5, 35%, respectively. The TATI value was correlated with the stage of the disease. Among the 15 patients without metastasis, the mean preoperative value was 112 micrograms/l (14-760) versus 46 micrograms/l (24-180) postoperatively. In the 9 patients with metastasis, the preoperative mean value was 100 micrograms/l (20-434) versus 240 micrograms/l (22-544) postoperatively. TATI showed a better sensitivity than other markers for RCC but its specificity is limited. Nevertheless it can be useful for a postoperative follow-up. TATI remains one of the best serum markers for RCC.

Biomarkers, Tumor↗
PubMed1995

[Organ culture of human tissue as study model of hormonal and pharmacological regulation of benign prostatic hyperplasia and of prostatic cancer].

We have established organ cultures of human prostate in vitro analysis of the hormone responsiveness of prostatic carcinoma. The influence of dihydrotestosterone (DHT), the epidermal growth factor (EGF) and prolactin (PRL) was assessed on the proliferation rate of 30 benign human prostatic hyperplasias (BPH) maintained for 48 hours as short-term primary cultures. The influence exerted by the EGF, the DHT and the PRL on the BPH cell proliferation was characterized by adding these compounds alone or in combination to the culture media. The proliferation rate was assessed by means of histo-autoradiographical nuclear labeling with titriated thymidine. The results show that of the DHT, EGF and PRL, the first two induced a statistically significant increase in the cell proliferation rate in a proportion of BPH significantly higher than the proportion of BPHs whose cell proliferation was increased significantly by the PRL. Furthermore, the PRL was able to antagonize the EGF-induced stimulatory effect on the BPH glandular cell proliferation rate. Lastly, the EGF- and PRL-mediated effects on the BPH glandular cell proliferation correlated with each other, while the DHT-mediated did not correlate with either the PRL- or the EGF-mediated effects. This model of organ, culture provide a basis for developing a method for in vitro testing of the individual hormone and drug responsiveness of a prostatic carcinoma.

Aged↗
PubMed1995

[Predictive value of the serum PSA level in patients having undergone neo-adjuvant hormone treatment before radical prostatectomy].

Great interest has been generated recently in preoperative androgen deprivation for clinical stage B ou C (T2 ou T3) prostate cancer. The influence of neoadjuvant hormonal therapy on down-staging and down-grading is still controversial. To assess the influence of preoperative androgen deprivation on serum PSA levels, we compared pre- and post-treatment serum PSA levels in 54 patients who received complete pre-operative androgen blockade (LHRH agonist + flutamide) 3 months prior to surgery. All patients with a pretreatment PSA > 20 ng/ml had extra-prostatic disease excepted two patients who presented lesions of acute prostatitis with adenocarcinoma. After hormonal deprivation, 51/54 patients experienced a return of PSA to normal values (< 4 ng/ml). Among this patient, 33 had undetectable PSA levels (< 0.25 ng/ml). 90% of the patients with undetectable had tumor confined to the gland (pT2/B). On the other hand, patients who still have PSA > 4 ng/ml after hormonal deprivation, had extra-prostatic cancer (pT3-pT4). Thus, PSA levels after 3 months neo-adjuvant hormonal treatment might have a useful predictive value in patients selection for radical surgery.

Adenocarcinoma↗
PubMed1994

Ureteral and bladder lesions after ballistic, ultrasonic, electrohydraulic, or laser lithotripsy.

Four techniques of intracorporeal lithotripsy are now available: ballistic, ultrasonic, electrohydraulic, and laser. Their therapeutic efficacies have generally been evaluated and compared, but very few data have been available on their relative risks of iatrogenic trauma to the urothelial wall. We conducted a comparative analysis of this risk by testing the pig ureteral and bladder wall with the EMS Lithoclast, Olympus ultrasonic lithotripter, Walz Lithotron EL 23, and Versa Pulse Ho:YAG Coherent Laser. We measured the number of shockwaves or the energy required to perforate the ureter and bladder by delivering shocks perpendicular to the walls. Ureteral perforation was impossible with the 1.0-mm Lithoclast transducer and the 1.5-mm ultrasound transducer. Perforation was induced after 250 shocks with the 0.8-mm Lithoclast transducer, after 110 shocks with the 3F electrohydraulic electrode, and after 0.02 kJ with the laser. Bladder perforation was impossible with the 2.0-mm Lithoclast device and the 3.4-mm ultrasound transducer but was induced after 0.04 kJ had been delivered with the laser. We evaluated the iatrogenic risk under normal conditions of use by delivering the shocks tangentially to the ureteral wall and perpendicular to the bladder wall. We sacrificed animals on days 0, 1, and 6. The immediate histologic lesions induced by the Lithoclast and the ultrasound lithotripter were similar, consisting of a moderate reduction of the epithelial layers or intraepithelial detachments. Electrohydraulic shocks induced almost complete abrasion of the urothelium, and the laser induced extensive lesions of partial or complete necrosis of the urothelial wall.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Microsurgical arterio-arterial and arterio-venous penile revascularization in patients with pure arteriogenic impotence.

OBJECTIVE: To restore physiological erection by performing microsurgical penile revascularization. PATIENTS AND METHODS: The records of 21 patients with pure arteriogenic impotence were reviewed. Thirteen patients with localized obstruction of the internal pudendal or common penile artery underwent a Michal II arterio-arterial penile revascularization. Eight patients with a more distal arterial obstruction underwent a penile deep dorsal vein arterialization (DDVA). The mean follow-up period was 22 months. Surgery was considered successful when the patients had a permeable anastomosis and were able to achieve satisfactory erections resulting in normal intercourse. RESULTS: Potency was restored in eight of the 13 patients who had a Michal II procedure and in five of the eight patients who had a DDVA. Under antithrombotic therapy graft occlusion occurred in four patients. CONCLUSION: Microsurgical penile revascularization restored erectile function in two-thirds of patients in this study. However, further research must be performed to reach a greater understanding of the revascularization process.

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↗