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Biomedical subjects

L Baert

Publications and source records attributed to L Baert.

At least 127 records · Page 7Linked to original sources
PubMed1993

Stone geometry and structure dependence on extracorporeal shock wave lithotripsy.

The in vitro fragmentation effects of electromagnetic-induced shock wave lithotripsy (Siemens Lithostar) were studied on parallel laminated schists in relation to the incoming shock wave energy and the incoming angle of the incident shock wave. Well above the threshold energy, the total amount of acoustic energy required for fragmentation remained unchanged regardless of the power setting of the high-tension supply. The amount of energy transmitted to the stone was limited by a total reflection angle, restricting the available transmission surface. These observations determine the effect of shock waves on calculi with an irregular shape such as staghorn stones. Lithotripsy-induced cavitation has been recognized, but no immediate influence on disintegration has become apparent until now.

Animals↗
PubMed1993

Transurethral microwave hyperthermia for benign prostatic hyperplasia: the Leuven clinical experience.

Local microwave hyperthermia, delivered transurethrally or transrectally, is a new treatment modality for benign prostatic hyperplasia. We started transurethral application, delivering 915-MHz microwaves at the prostatic urethra using a helical microwave antenna incorporated in a Foley catheter. This hyperthermia was given without a urethral surface cooling system. Thermophysical testing of the applicator proved therapeutic efficacy in vitro and in vivo. Pathologic studies demonstrated hyperthermia-induced lesions in the periurethral prostatic tissues and permitted us to hypothesize a working mechanism of transurethral hyperthermia. Clinical Phase I and II studies showed clinical efficacy in patients with urinary retention or prostatism secondary to benign hyperplasia, especially in bilobar or trilobar prostatic configurations. While awaiting results of further pathologic and thermophysical experimental work and ongoing Phase II and III studies, we consider transurethral hyperthermia an investigational but promising conservative treatment modality for benign prostatic hyperplasia.

Belgium↗
PubMed1993

New trends in the treatment of benign prostatic hyperplasia and carcinoma of the prostate.

Benign prostatic hyperplasia (BPH) is a very common condition affecting over 800,000 American males each year. A standard, effective, and well-proven therapy is prostatectomy. This surgical procedure is used to treat, in the United States, approximately 400,000 BPH patients annually. Major treatment benefit is expected in 70% to 80% of patients. Complications are seen in 20% of the surgically treated patients. Due to the advanced age of BPH patients and the presence of other serious coexisting medical problems, surgical therapy may be difficult to utilize. These patients, who present a high risk for surgery, are in need of alternative treatments. Alternative therapy in BPH patients with clinically important symptoms and signs of urinary outflow obstruction include treatment with pharmacological agents, balloon dilatation, laser beam therapy, transurethral thermal therapy, transrectal microwave hyperthermia, and transurethral microwave hyperthermia. These alternative treatment modalities are currently under intensive study. These new treatment modalities ultimately must be compared with the standard treatment, which is prostatectomy. Due to the unpredictable natural history of BPH, it is desirable that each Phase III study should contain a no-treatment observation-only arm. Adenocarcinoma of the prostate (CaP) has become a tumor, which first in frequency, and second in importance in cancer mortality statistics of American males. Local tumor control rates and long-term survivals, with radical prostatectomy or radiation therapy, have been excellent. There was, however, recent concern regarding a high incidence of microscopic local tumor recurrence following a definitive course of irradiation. Deep regional or intracavitary hyperthermia (HT) with phase steering may be of value as an adjuvant treatment to radiotherapy. This HT may increase the incidence of local tumor control obtained with radiotherapy. Phase I-II clinical studies are currently underway.

Adrenergic alpha-Antagonists↗
PubMed1993

Pharmacokinetics and anthelmintic efficacy of febantel in the racing pigeon (Columba livia).

This paper reports on the pharmacokinetics and the efficacy of febantel against Capillaria obsignata and Ascaridia columbae in the racing pigeon. Febantel was rapidly cleared from the circulation and highly metabolized. The efficacy of febantel against Capillaria and Ascaridia was studied on lightly and heavily infected pigeons. The efficacy against Ascaridia was 100% for the faecal egg count reduction (FECR) as well as for the worm reduction in all treated pigeons. After two treatments with febantel against Capillaria in heavily infected pigeons the FECR amounted to 96.7% and worm reduction was 95%. In order to effectively remove both parasites from the host, repeated treatments with febantel at a short interval could be the treatment of choice.

Animals↗
PubMed1993

Pelvic floor exercise versus surgery in the treatment of impotence.

A group of 150 consecutive male patients with erectile dysfunction and proven venous leakage were randomised either to surgery or to a pelvic floor training programme. The operative procedure consisted of dissection and removal of the deep dorsal vein of the penis and its tributaries or large veins that drain into the internal or external pudendal system. The training programme was given 5 times, in weekly sessions, and the patients were supervised by trained physiotherapists. Surgery was not superior to the pelvic floor training programme either subjectively or objectively. Moreover, a significant improvement was found following the training programme; 42% were satisfied with the outcome and refused surgery. Pelvic floor exercise is a realistic alternative to surgery in patients with mild degrees of venous leakage.

Adult↗
PubMed1993

Prophylactic role of extracorporeal shock wave lithotripsy in the management of nephrocalcinosis.

Electromagnetic extracorporeal shock wave lithotripsy (ESWL) was performed with a standard Siemens Lithostar on parenchymal calcifications in 10 medullary sponge kidneys in order to evaluate the eventual benefit of preventive lithotripsy. The results of shock wave lithotripsy on precaliceal calcifications were disappointing and have been related to the lack of expansion during shock wave interaction and to the impaired drainage of particles. Three patients also had large impacted ureteric stones and in such cases ESWL remains the treatment of choice.

Adult↗
PubMed1993

In vitro analysis of urinary calculi: type differentiation using computed tomography and bone densitometry.

Thirty-six urinary stones were studied by computed tomography and bone densitometry in order to find a correlation between the chemical composition of the stones and the densitometric data. In vitro, the more common cases of lithiasis can be divided into 3 main groups: uric acid, cystine and the calcium salts, e.g. calcium oxalate monohydrate, calcium oxalate dihydrate and calcium phosphate. Struvite stones fall between the second and third groups. Computed tomography and bone densitometry can differentiate between the groups, provided that the value of the "stone mineral or calcium content" is correlated with the true calculated volume of the stone (resulting in the specific stone density) instead of the projection area (resulting in the area density). This is only possible in vitro. The in vivo application of these technologies in the treatment of stones of unknown composition could provide important information, but major restrictive factors pose difficulties. Further clinical studies are necessary, especially to define the role of bone densitometry.

Absorptiometry, Photon↗
PubMed1993

Submucosal migration of ureteric calculi: related to ESWL?

Three patients were reinspected by ureteroscopy after repeat ESWL. Ureteroscopy initially did not disclose an intraluminal stone and only visualized a severe inflammatory reaction of the ureteric wall and a boss of the ureter at the level of the fluoroscopically suspected stone location. An intact stone in all 3 cases was finally exposed by tactile contact at the top of the ureteroscope after perforating the mucosa with a guide wire. Retrospectively, the combination of long-standing stone impaction together with damage to the ureteric mucosa during shockwave interaction may cause an inflammatory reaction with submucosal migration of the stone.

Aged↗
PubMed1993

Pelvi-perineal rehabilitation for dysfunctioning erections. A clinical and anatomo-physiologic study.

We have studied penile structure in 24 cadaver specimens and 155 patients have been treated for organic impotence by physiotherapy. Special attention has been focused on the closure mechanism of the corpora cavernosa during erection. We have found that the leakage factor of the corpora cavernosa is, among other things, influenced by the ischiocavernous muscles. Based on the above, we propose a model for the anatomic and physiologic basis of interference of the ischiocavernous muscles in venous occlusion during penile erection. Moreover we suggest that patients with erectile dysfunction should undergo pelvi-perineal rehabilitation in order to strengthen and control ischiocavernous muscles.

Adult↗
PubMed1993

Value of MRI in the diagnosis and staging of testicular tumors.

Ultrasound is currently the primary imaging modality for the assessment of scrotal disease. In acute pathology, colour Doppler adds further confirmation about blood flow to the testicles and surrounding structures. MR is emerging as a powerful tool to image the scrotum. Compared with sonography, MR has a wider field of view and a greater tissue contrast. The current status of MR imaging and its role in the evaluation and local staging of testicular tumors is evaluated in this retrospective study. MR is able to differentiate seminomatous from non-seminomatous tumors in nearly all cases. However, stromal tumors (e.g. Leydig cell tumors) cannot be differentiated from seminomatous tumors, and some benign lesions, as an intratesticular hematoma, cannot be differentiated from non-seminomatous tumors. Microscopic extension in or beyond the tunica albuginea cannot be evaluated.

Dysgerminoma↗
PubMed1992

Trisomy 7 and trisomy 10 characterize subpopulations of tumor-infiltrating lymphocytes in kidney tumors and in the surrounding kidney tissue.

We performed conventional cytogenetic analysis and fluorescence in situ hybridization in short-term cultures of normal and neoplastic kidney tissues. Cell populations carrying an extra chromosome 7 or an extra chromosome 10 as the only chromosome change could be identified in kidney tumors, mostly renal cell carcinomas, and in the surrounding kidney tissue, but not in nonneoplastic kidneys. To identify the type of cells displaying these aneuploidies, we performed in situ hybridization (ISH) with probes specific for the centromeric region of chromosomes 7 and 10 on frozen kidney tissue sections. Trisomy 7 and trisomy 10 were restricted to infiltrating inflammatory cells in the tumor as well as in the surrounding tissue. Trisomy 7 and trisomy 10 were also found in subpopulations of peripheral blood T cells of cancer patients and of normal individuals, as well as in the thymus of five normal fetuses (21-29 weeks), but not in noninvaded reactive lymph node sections of patients without malignancy. When lymphocytes were enriched from kidney tumors and surrounding tissue by either Ficoll/Hypaque density gradient or immunomagnetic selection with anti-CD3, anti-CD4, or anti-CD8 monoclonal antibodies, it was confirmed that they contained a high percentage of trisomy 7 and trisomy 10 cells. Further proof for T-lymphocyte origin of the trisomy 7 and trisomy 10 cells was obtained by simultaneous staining of lymphocytes isolated from tumor tissue with anti-CD3, anti-CD4, and anti-CD8 monoclonal antibodies and ISH. We conclude that trisomy 7 and trisomy 10, found in renal carcinomas and surrounding kidney tissue, characterize subpopulations of tumor-infiltrating lymphocytes. The biologic significance of this phenomenon is unknown and requires further investigation.

Chromosomes, Human, Pair 10↗
PubMed1992

Temperature steering in prostate by simultaneous transurethral and transrectal hyperthermia.

Localized hyperthermia (HT) is presently under investigation as a treatment for benign prostatic hyperplasia and carcinoma of the prostate (CaP). One popular approach employs a transrectal (TR) device, a directional microwave (MW) applicator inserted into the rectum and aimed at the prostate. Alternatively, in the transurethral (TU) technique, a symmetrically radiating MW antenna is placed directly within the prostatic urethra. Used individually, TR applicators are capable of effectively heating (> 42 degrees C) the prostate up to 2 cm from the rectum, whereas TU applicators selectively heat the periurethral tissue with effective radial penetration of about 0.6 cm. Neither technique is of much value in heating the anterior prostate. In general, the highest temperatures are produced in the tissue immediately adjacent to the surface of intracavitary microwave devices. However, when MW antennas are used in arrays, the resulting heating pattern can differ significantly from that of the individual antennas. Heating at depth can be selectively enhanced and "steered" by adjusting the phase relationship between the devices. Prostatic temperature profiles were measured in 6 patients treated with TR alone, TU alone, and simultaneous TR and TU heating. In the combined treatments different phase relationships between the antennas were applied. We found that a higher temperature could be produced in the center of the prostate than on the surface of either applicator for certain phase relationships, and that the temperature profiles could be changed by shifting phase. The results of these measurements are in agreement with those of a computer simulation. Based on the above data we feel the combined use of TU and TR hyperthermia may be justified in Phase I-II trials for patients with locally advanced CaP.

Aged↗
PubMed1992

Relationship of response to transurethral hyperthermia and prostate volume in BPH patients.

A response to transurethral microwave hyperthermia (TUHT) at 915 MHz and its relationship to prostate volume was examined in 63 poor surgical risk benign prostatic hyperplasia (BPH) patients. All patients had moderate-to-severe obstructive signs and symptoms, and received > or = 5 TUHT one-hour sessions. Treatment temperature was controlled on the urethral surface at 45 degrees C +/- 1 degree C. Follow-up ranged from twelve to forty-four months (mean 18 months). The mean prostate volume was 57 cc (range 10-301 cc). There were 40 patients (63%) with prostate volume < or = 50 cc and 23 (37%) with a volume > 50 cc. Treatment failure was seen in 6 patients (10%). It was 10 percent in 40 patients with smaller glands and 9 percent for those 23 with larger prostates, N.S. at p = 0.49. Subjective treatment response was seen in 58 patients (92%). It was 90 percent for the 40 patients with < or = 50 cc prostates vs. 96 percent for the 23 with > 50 cc prostates, N.S. at p = 0.75. This study suggests that the initial prostate volume is not an important parameter predicting response to TUHT.

Aged↗
PubMed1992

Electromagnetic extracorporeal shock wave lithotripsy for calculi in horseshoe kidneys.

Between June 1987 and January 1991, 11 renal units in 10 patients with horseshoe kidneys were managed by electromagnetic extracorporeal shock wave lithotripsy (ESWL) monotherapy with a Siemens Lithostar. A total of 33 calculi was treated in 42 sessions. All treatments were performed without anesthesia and on an outpatient basis. All calculi could be targeted by standard installation techniques. The maximum number of shock waves per session was 4,000, which implies per stone an average of 1.3 sessions and an average of 4,903 shock waves (range 1,800 to 9,000) at a mean energy setting of 17.8 kv. Complete disintegration or fragmentation into spontaneously passable particles was achieved in 27 calculi, for a success rate of 83% when considering the results in regard to the individual stone locations. Per renal unit, an average of 3 calculi were targeted and after an average of 3.8 sessions 6 units became stone-free. Horseshoe kidneys, when calculous, contain dispersed and multiple calculi and from these data approximately 1 session per stone must be planned. The number of treatments per renal unit increased in proportion to the number of calculi and to the presence of calculi with low fragility. Of 21 lower pole calculi 18 completely evacuated and this observation has been related to the more medial location of the inferior calices near the ureteropelvic junction. No impaired drainage of fragments was noted to be related to the horseshoe anatomy. Patency of the ureteropelvic anatomy appeared to be the main parameter for the evacuation of fragments. Neither preoperative nor postoperative adjuvant maneuvers have been necessary.

Adult↗