Conformational kinetics of disaccharides in aqueous solutions

Between 100 kHz and 2 GHz ultrasonic attenuation spectra of disaccharides in water have been measured at 25 degrees C. Some additional measurements have been performed at different temperatures between 10 and 35 degrees C and as a function of saccharide concentration c (0.5 mol/l</=c</=1.8 mol/l). The analytical description of the spectra in terms of relaxation spectral functions revealed four relaxation regimes. Three relaxation regions correspond to such revealed by monosaccharides in solution. These relaxations reflect a pseudorotation, an exocyclic hydroxymethyl group rotation, and probably a saccharide-saccharide association. The relaxation term with relaxation time between 3.6 and 19 ns (25 degrees C) is characteristic for the disaccharide solutions. It has been assigned to a rotation of the disaccharide rings relative to one another.

Kinetics of Ca2+ complexation with some carbohydrates in aqueous solutions

For solutions of four saccharides in water with alkaline-earth chlorides added ultrasonic attenuation spectra between 100 kHz and 2 GHz are reported and compared to those for carbohydrate solutions without salt. Calcium chloride does not alter the relaxation times in the spectra of D-glucose and D+-maltose solutions, reflecting the exocyclic hydroxymethyl group rotation, a saccharide-saccharide association, and, with the disaccharide, also motions of both rings of a molecule relative to one another. The spectra of D-xylose and D-fructose solutions are substantially changed by the salts. With both saccharides an additional term with relaxation time around some nanoseconds exists which is assigned to a rearrangement of a carbohydrate-cation complex. Other relaxation terms of these saccharide solutions are also subject to noticeable changes by the salt, indicating specific carbohydrate-cation interactions. The ultrasonic spectra show that such interactions may exist also with carbohydrates which do not display the particular hydroxyl group sequences that are considered to promote complexation with cations.

[Tracheostoma valve with integrated cough lid for improvement of hands-free speech in laryngectomees - long term results]

BACKGROUND

Tracheostoma valves for laryngectomized patients were introduced to enable the laryngectomee after successful surgical voice restoration either by a voice prosthesis, a surgical shunt or microvascular laryngoplasty, to speak without using his fingers to close the tracheostoma. The basic principle of these aids is a mobile valve, which closes automatically at a certain air flow, directing the expired air of the lungs into the pharynx. In spite of the clear advantage of enabling a hands-free speech, the long term acceptance rate is still rather low, which is mainly caused by problems of an airtight fixation within or at the tracheostoma. Another important disadvantage of these tracheostoma valves is the necessity of removing the valve during coughing. The new tracheostoma valve "Window" (ADEVA Company, Lübeck, Germany) offers a clear improvement regarding this point. It is constructed with an additional coughing lid, which opens at a certain airflow and closes automatically after the coughing attack. After successful development and clinical testing of the new aid in 1999 and 2000, it was now the question, if the previously low acceptance rate of tracheostoma valves could be improved in the long term use by this new type of valve.

PATIENTS

Within the last 4 years 70 patients were provided with the "Window" tracheostoma valve. Patients were followed up at regular intervals in order to evaluate the function, the acceptance and the durability of the new device. Additional to the clinical examination patients had to fill in a questionnaire in order to investigate the subjective estimation by each patient himself. 15 patients did not send back their questionnaire or did not fill it in correctly, 5 patients refused clinical supervision after adjustment of the device, so finally the long term use in 50 patients could be analysed.

RESULTS

82 % of the patients reported, that the coughing lid worked safely and opened immediately during the coughing attack. Most of the patients were satisfied with their device, but had nevertheless some proposals for a further improvement: although they cover the tracheostoma either with their clothes or a protection scarf, most of the patients would prefer a device which is smaller than the current model. Some patients reported on an insufficient stability of the plastic material, which led to a defect at the sliding mechanism of the coughing lid. The greatest problem regarding the regular use of the valve was - comparable to conventional tracheostoma valves - the occurrence of an air leakage around the tracheostoma. Although there are three different models of the "Window" tracheostoma valve available, only patients being fitted with the "standard-T-type" version could wear the device 10 hours a day or longer without any problems of air leakage.

CONCLUSIONS

The "Window" tracheostoma valve with an integrated coughing lid provides further improvement in speech rehabilitation of laryngectomees. The actual rate of acceptance of 62 % for all "Window" patients (1 month daily use for at least 2 hours) is superior to other reports on the use of tracheostoma valves and probably caused by the additional comfort provided by the coughing lid. Another important factor for the long term use of tracheostoma valves is however the safe fixation of the device in or around the tracheostoma. In this point further improvement is necessary, as only the model with the fixation within the trachea (T-type) led to a satisfactory long term airtight fixation.

Zherlock: an open source data analysis software

Zherlock is an open source software that provides state-of-the-art data analysis tools to the user in an intuitive and flexible way. It is a front-end to different numerical "engines" to produce a seamless integration of algorithms written in different computer languages. Of particular interest is creating an interface to high-level scientific languages such as Octave (a Matlab clone) and R (an S-PLUS clone) to enable efficient porting of new data analytical methods. Zherlock uses advanced scientific visualization tools in 2-D and 3-D and has been extended to work on virtual reality (VR) systems. Central to Zherlock is a visual programming environment (VPE) which enables diagram based programming. These diagrams consist of nodes and connection lines where each node is an operator or a method and lines describe the flow of data between nodes. A VPE is chosen for Zherlock because it forms an effective way to control the processing pipeline in complex data analyses. The VPE is similar in functionality to other programs such as IRIS Explorer, AVS or LabVIEW.

[Are titanium implants superior to gold implants in the tympanic cavity?]

BACKGROUND

Gold implants in reconstructive surgery of the middle ear have proved to work sufficiently: That applies to tympanic cavity conditions without signs of chronic inflammation as also to the bacterially infected middle ear. For some years titanium implants are also in the use and established as well. The biocompatibility of titanium, the clinical and the audiological results are satisfactory. When using gold-prostheses in stapes surgery however, the still unsolved problem of occasional deafness has to be considered.

PATIENTS

The clinical and functional results of middle ear surgery were examined retrospectively. There was no preselection of patients. 53 patients underwent middle ear surgery with titanium prostheses, 42 patients with gold prostheses.

RESULTS

Due to their material properties and due to their delicate shape titanium prostheses (PORP, TORP) can be inserted into the tympanic cavity more simply and with better fit. The audiological results of gold and titanium prostheses are comparable. The extruding rate of the gold prostheses is substantial, whereas the extruding rate of titanium is negligible.

CONCLUSION

The functional results of both materials are comparable. Due to the high extruding rates of gold prostheses titanium is clearly superior.

[Mechanical ileus caused by a Provox voice prosthesis -- an "iatrogenic" enteral complication in voice prosthesis rehabilitation of laryngectomees]

BACKGROUND

During the exchange of a defect Provox-I voice prosthesis followed by an insertion of a Provox-II voice prosthesis the esophageal part of the prosthesis often is pushed into the esophagus, as the enteral passage of the prosthesis was thought to be less traumatic for the voice shunt in comparison to a complete extraction of the stiff esophageal flange through the tracheostoma. This procedure is also recommended in the users video of the ATOS company.

CASE

A laryngectomized patient, in whom the change of the voice prosthesis was carried out pushing the esophageal flange of the prosthesis into the esophagus, developed a mechanical ileus, as the voice prosthesis got stuck in Bauhin's valve. This resulted in the necessity of a laparatomy for removal of the voice prosthesis.

CONCLUSION

During the replacement of the Provox voice prosthesis it is necessary in all cases that the esophageal remnant of the voice prosthesis either is pulled out of the tracheoesophageal shunt via the tracheostoma or removed with a guide-wire transorally.

[Functional long-term results following hemipharyngo-hemilaryngectomy and microvascular reconstruction using the radial forearm flap]

BACKGROUND

The surgical treatment of advanced hypopharyngeal carcinomas with infiltration of the laryngeal skeleton often includes total laryngectomy for functional reasons, although tumor infiltration is limited to only one half of the larynx. When not only the infiltrated half of the thyroid cartilage but also the cricoid cartilage of the involved side has to be removed, in spite of adequate reconstruction using local or pedicled flaps (f. e. pectoralis major flap) persistent dysphagia and aspiration prevent oral food intake and closure of the tracheostoma. These functional disturbances are increased by the negative effects of postoperative radiotherapy, which has to be applied in most of the cases for oncological reasons. The routine use of free, microvascularly anastomosed flaps for reconstruction of defects following removal of extended carcinomas of the mouth, the tongue or the oropharynx as well as in total pharyngolaryngectomy led to considerable improvements in functional rehabilitation of swallowing and speech. An improved functional outcome is also reported following partial resections of the hypopharynx and reconstruction by means of these thin and pliable transplants (f. e. replacement of the entire posterior hypopharyngeal wall).

METHOD

Since 1991 in 30 patients with a T3 or T4 squamous cell carcinoma of the piriform sinus a complete hemipharyngo-hemilaryngectomy including resection of the involved thyroid and cricoid cartilage was carried out. For reconstruction a radial forearm flap was dissected with two separate epithelial islands: The smaller island was used to create an epithelialized endolarynx, which allows complete closure of the glottis by the healthy vocal chord. With the bigger second island the hypopharynx was replaced, creating a highly mobile, adaptable neo-piriform-sinus, which was suspended to the ipsilateral half of the hyoid bone. Parts of the both islands were sutured together to create a new aryepiglottic fold. The laryngeal skeleton intentionally was not reconstructed.

RESULTS

One year evaluation revealed 25 of the 30 patients swallowing normal diet and being decannulated. 4 patients could take up a soft diet, 1 patient with a severe stricture at the entrance to the esophagus however had to be laryngectomized for functional reasons. Most of the patients judged their postoperative voice as satisfactory, although there was a different impairment of the voice (quite normal up to a marked hoarseness). During follow-up (up to 10 years) 4 patients developed a local recurrence, in 3 cases a secondary metastasis after neck dissection occurred. In 3 patients a second primary was detected (oropharynx 2, esophagus 1), 3 patients died with lung metastases.

CONCLUSION

Rehabilitation of normal swallowing and a satisfying voice restoration without a permanent tracheostoma following complete hemipharyngo-hemilaryngectomy can obviously be improved by the use of microvascular transplants (here radial forearm flap) in comparison to other surgical techniques. The necessary radical extirpation of these extended carcinomas also is guaranteed like in total laryngectomy, so that in spite of the advanced tumor stage an organ preserving surgery can be offered. A prolonged course of swallowing rehabilitation however has to be taken into consideration.

A highly specific one-step PCR - assay for the rapid discrimination of enteropathogenic Yersinia enterocolitica from pathogenic Yersinia pseudotuberculosis and Yersinia pestis

Based on differences within the yopT-coding region of Yersinia. enterocolitica, Y pseudotuberculosis and Y pestis, a rapid and sensitive one-step polymerase chain reaction assay with high specificity for pathogenic Y enterocolitica was developed. By this method pathogenic isolates of Y enterocolitica can be easily identified and discriminated from other members of this genus. The entire coding sequence of the yopT effector gene of Y. pseudotuberculosis Y36 was determined.

[Tracheostomy valve with integrated cough flap for improving hands-free speech in laryngectomized patients--development and clinical applications]

BACKGROUND

Following successful voice restoration after laryngectomy either by a voice prosthesis, a surgical shunt or microvascular laryngoplasty, a further goal in rehabilitation is the insertion of a tracheostoma valve, which enables the patient to speak without using his fingers for closure of the tracheostoma. One important disadvantage of the tracheostoma valves, which are available today, is the necessity of removal of the valve in case of coughing, because the valve could be thrown from the stoma by the strong air flow during coughing. As many laryngectomies suffer from chronic bronchitis, this coughing problem is one of the reasons why only few patients could be provided with this useful aid.

METHOD

At the department of biomedical engineering of the faculty of medicine at the university of Groningen, the Netherlands, 1994 two prototypes of a tracheostoma valve with an integrated cough lid were developed. These devices contain two separate valve systems: the normal speaking valve and a special coughing valve, which opens at a certain air flow and closes automatically after the coughing attack. Thus no manipulations are necessary during coughing, the patient can speak undisturbed. The ADEVA company (Lübeck, Germany) undertook the industrial production of this new type of tracheostoma valve creating different modifications of the prototype #2.

PATIENTS

In four series with 6-8 patients per group the modified tracheostoma valves were tested clinically and the occurring faults or lack of correct function eliminated by small changes in the production.

RESULTS

Meanwhile a suitable model for routine use is available, which was tested in 30 patients so far. This suitability was achieved by improvements in the valve mechanism, the valve seal and the adjustment mechanisms for the individual pressure level of the speaking and the coughing valve.

CONCLUSION

The newly developed tracheostoma valve with integrated coughing lid (Window, ADEVA-medical Company, Lübeck, Germany) provides further improvement in speech rehabilitation of laryngectomies. The low acceptance of tracheostoma valves, which enable the patient to speak without using his fingers for closure of the tracheostoma, possibly may be raised by this new aid.