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Biomedical subjects

W Schuessler

Publications and source records attributed to W Schuessler.

7 recordsLinked to original sources
PubMed2003

NOM-facilitated transport of metal ions in aquifers: importance of complex-dissociation kinetics and colloid formation.

The transport of metal ions (Al, Fe, Zn, Pb) complexed by natural organic matter (NOM) was investigated by column experiments. Direct breakthrough of metal-NOM complexes was observed after elution of one bed volume for Al, Fe, and Pb, but not for Zn. This observation cannot be understood assuming local thermodynamic equilibrium in the columns. Hence, a model was developed, taking into account the kinetics of the interactions of metal ions with NOM and the solid phase. Of all possible reactions during passage through the column, the dissociation of the metal-NOM complexes was assumed to be the rate-determining step. Dissociation-rate constants were determined by cation-exchange experiments with a non-NOM-adsorbing cation-exchange resin (Chelex-100). These rate constants were used to predict the migration of metal-NOM complexes in the column experiments. Experimental and modeling results were in good agreement for the bivalent metal ions. Also, the model well predicted the pH dependence of breakthrough of trivalent metal ions and the differences between Al and Fe breakthrough on a qualitative basis. This leads to the conclusion that the dissociation kinetics of metal-NOM complexes is an essential parameter for the estimation of NOM-facilitated metal transport. However, for the trivalent metals, Al and Fe, the model overestimated the direct breakthrough, thus giving a worst case prediction of metal transport. With the help of coupling size-exclusion chromatography to inductively coupled plasma-mass spectrometry, the formation of Al-hydroxide and Fe-hydroxide colloids in addition to NOM complexes was detected. These colloids, which were not considered in the model, were partially filtered off in the column, thus leading to overestimation of metal breakthrough.

Chromatography, Gel↗
PubMed1993

Complications of laparoscopic pelvic lymph node dissection.

Intraoperative and postoperative complications were assessed in the first 372 patients undergoing laparoscopic pelvic lymph node dissection at 8 medical centers. In 16 patients laparoscopic node dissection could not be completed due to patient body habitus or technical difficulties. Of these aborted procedures 14 occurred during the initial 8 dissections at each institution. A total of 55 complications (15%) occurred: 14 were noted in the intraoperative and 41 in the postoperative period. Of these patients 13 required open surgical intervention for the treatment of a complication. Complications included vascular injury (11 patients), viscus injury (8), genitourinary problems (10), functional/mechanical bowel obstruction (7), lower extremity deep venous thrombosis (5), infection/wound problem (5), lymphedema (5), anesthetic complications (2) and obturator nerve palsy (2). Based on our experience, there is a significant learning curve associated with performing laparoscopic pelvic node dissection. However, with experience and adherence to laparoscopic surgical principles, the risk of complications may be minimized.

Adenocarcinoma↗
PubMed1993

Efficacy of endoscopic hydrocele ablation.

We describe a new endoscopic technique that was used for the treatment of symptomatic scrotal hydroceles in 10 men. Through a small skin incision, the parietal surface of the tunica vaginalis was ablated endoscopically using either electrocautery or the KTP:YAG laser. This approach permitted visual inspection of the scrotal contents with minimal manipulation and was performed using monitored local anesthesia with bilateral spermatic cord blocks. With a mean follow-up interval of 6.1 months, no hydrocele recurrences, wound infections, or hematomas have been detected. The mean operative time was comparable (53 minutes) to that in a historical control group consisting of 15 men who had undergone open hydrocelectomy at our institution (46 minutes). Postoperative scrotal discomfort was minimal, with 6 of the 10 patients requiring no analgesics. Patients were able to resume their preoperative lifestyles an average of 2 days after surgery. In contrast, 11 of the 15 men in the control group was still complaining of scrotal pain, requiring oral analgesics, at their 2-week follow-up visit. Thus, endoscopic hydrocele ablation appears to be an effective and well-tolerated alternative to treat hydroceles with minimal postoperative discomfort.

Adult↗
PubMed1992

Endoscopic hydrocele ablation.

A new technique for the treatment of hydroceles by percutaneous drainage and endoscopic ablation under direct vision is described. The possible benefits and drawbacks of this treatment modality for symptomatic hydroceles are discussed.

Catheter Ablation↗
PubMed1991

Laparoscopic bladderneck suspension.

Nine consecutive patients with genuine stress urinary incontinence and without any other concomitant pathology, underwent laparoscopy for surgical correction of their condition. Besides the method of access to the space of Retzius, the procedure was identical to the one original described by Kranz. In 2 of the 4 first patients, a laparotomy had to be performed to complete the surgery. The 7 other patients could leave the hospital within 24 hours of the surgery and 6 of them without catheter. At follow up, one of the 7 patients complained of mild urgency symptoms which had not been present prior to surgery. Laparoscopic bladderneck suspension is feasible. This procedure offers the general advantages of the endosurgical approach and possibly entails additional improvements. However, there is a definite learning curve for the surgeon prior to mastering this technique.

Hospitalization↗
PubMedDate not supplied

Laparoscopic colonic procedures.

With the advent and general acceptance of laparoscopy as a means of surgically treating intraabdominal disease processes, procedures on organs other than the gallbladder and female genital tract have slowly evolved. After developing basic techniques in an animal model, a clinical series (n = 19) of laparoscopic procedures for a variety of colonic lesions was undertaken and is herein presented. It included both malignant and nonmalignant disease processes and has carried an acceptable complication rate and survival. The average age of our patients was 68, and except for two extended postoperative hospitalizations and one death for non-procedure-related complications, the patients were generally ready for discharge in less than 96 hours. Our current techniques and indications for laparoscopic colonic surgery are detailed.

Aged↗