Stratospheric ozone effects on temperature.

Calculated surface temperature changes, DeltaT(8), due to stratospheric ozone depletion (at 35 degrees N latitude in April) are less than previously estimated and range between -0.6 and +0.9 degrees K. The sign of DeltaT(8), is determined by the surface albedo and the presence or absence of a low-lying particulate layer (heating with particles, cooling without particles). The calculations indicate that a 90 percent stratospheric ozone depletion does not cause the temperature inversion at the tropopause to vanish, although it is weakened substantially.

Aerosols in the atmosphere: calculation of the critical absorption/backscatter ratio.

The ratio of the absorption coefficient to the backscatter coefficient for which heating and cooling effects due to aerosols exactly balance at the earth's surface has been calculated with the use of a radiative-convective atmospheric model. The results are compared with those obtained from several simpler mean radiative-transfer models.

Aerosols and polar temperature changes.

Calculations indicate that aerosols are not directly responsible for the present increase in ice abundance in the Northern Hemisphere. Indeed it appears that aerosols cause heating of the atmosphere near the poles. The present background aerosol density at 85 degrees S latitude causes a temperature increase of approximately 0.2 degrees K, while that at 85 degrees N causes an increase of approximately 0.05 degrees K.

[Chronic back pain and expert opinion]. / Der chronische Rückenschmerz und seine Begutachtung (I).

Back pain, especially chronic back pain, is not only a medical and psychological burden but also an economic problem due to the extremely high associated costs. These are generated by treatment and rehabilitation measures, pensions and loss of working hours. The cause of pain is multifocal and frequently remains unclear. It is not the etiology of back pain that has changed in the last 20 years, but its rate of assessment and treatment options. According to the relevant literature, treatment of chronic back pain will most probably only succeed using multimodal concepts that have to consider medical/somatic and psychosocial aspects and be based on scientific training experience. Pain assessment is based on common legal and certification standards. However, typical decision and rating problems result from the difficulty of objective medical registration and grading of pain. Medical certification may often be complicated by co-morbidities such as somatic pain attacks, fibromyalgia, depression or anxiety. These cases necessitate close cooperation with other medical specialities.

Bioactive glass-ceramics in middle ear surgery. An 8-year review.

An 8-year follow-up of Ceravital middle ear prostheses showed there was extremely good tolerance in the middle ear space. Incompatibility phenomena were not observed, and inflammatory reactions were neither caused nor supported by the implants. The tympanoplasties were always performed without interposition of cartilage between the tympanic membrane or the tympanic membrane graft and the disk-shaped portion of the implant, and extrusions were never observed. Long-lasting inflammatory processes appeared to destroy implants the same way they destroy ossicles. Transient inflammatory periods (such as episodes of purulent otitis media, which occurred soon after the prostheses were implanted) did not lead to any remarkable changes of the surface of the implant. In healthy middle ears, the hearing results were stable.

Value and limits of computer-assisted tomography.

Three years ago, at the VIIth International Congress of Radiology in Otorhinolaryngology, held in Copenhagen, the early impressive results of computer-assisted tomography (CAT) in otorhinolaryngology were presented. Since considerable technologic and diagnostic progress of CAT has taken place in the meantime, questions about the increase in CAT's value and the expansion of its limits are appropriate now. Computed and, in some cases, conventional tomograms of facial lesions are used in the discussion of these questions. There is no doubt of CAT's advance within the last few years; there are, however, limits of CAT to be emphasized: (a) coronal CAT might be uncomfortable (especially if the gantry cannot be tilted), unsuccessful (e.g., in cases of neck stiffness), and even dangerous (when head injury is combined with trauma to the cervical spine); (b) enhancement is often not useful (except when intracranial tumor invasion is suspected); (c) specific diagnosis, based on CAT findings only, is impossible in most cases; (d) the radiation dose, which increases with improvement in the quality of the image, must be considered in each case; and (e) CAT does not replace conventional x-ray techniques, least of all polytomography.

Bioactive glass-ceramics in ear surgery: animal studies and clinical results.

In the search for better materials for middle ear reconstruction, ceramics have been suggested as an alternative. The bioactive glass-ceramic Ceravital was made available to us for animal experiments and clinical trials. To test its suitability in ear surgery, 101 ear operations were carried out in 53 rabbits including the reconstruction of 78 posterior auditory canal walls and the insertion of 174 middle ear implants. Parameters studied include the effects of bone paté in inducing new bone growth, the chronological course of bone apposition and remodeling, microscopic examination of mucous membrane growth on the implants and degree of lysis of the implant. In the past two and one half years some 250 ossicular prostheses have been implanted in man for reconstruction of the ossicular chain. A statistical analysis of 119 tympanoplasties after a follow-up of one and one half years shows no perforations of the tympanic membrane over the implants or rejection of the prosthesis from the middle ear. The audiological results achieved were more favorable with the use of ossicular prostheses made of bioactive glass-ceramic than those using allogenic ossicular grafts. On the basis of the histologic findings and observed clinical results, the bioactive material Ceravital is remarkably well suited for reconstruction of the posterior auditory canal wall and for implantation in direct contact with the tympanic membrane.

Bioactive glass ceramic: a new material in tympanoplasty.

The practicability of the bioactive glass ceramic Ceravital in ear surgery was tested in animals. The histological findings are presented. Over the last 3 years implants of bioactive glass ceramic were used in humans. Prostheses for the total or partial reconstruction of the ossicular chain and the reconstruction of the bony wall of the outer ear canal were fashioned. We have conducted about 300 tympanoplasties and 60 total or partial reconstructions of the bony wall of the outer ear canal. The otoscopic and functional results were satisfactory.

[Reoperations in otosclerosis. Indications, intraoperative findings, and results]. / Las reintervenciones en la otosclerosis. Indicaciones, hallazgos intraoperatorios y resultados.

The audiological outcome of 140 stapedectomy revisions done between 1977 and 1987, as well as the pre- and intraoperative findings and the subjective appraisal of the revisions, are presented. The recurrence of the conductive deafness was the most often indication for the surgical revision and the shift of the prosthesis, verified intraoperatively, the most encountered finding. Audiological results showed, as mean value, an important reduction of the transmissive hearing loss whilst the bone conduction remained unaltered. Patients' subjective evaluation of the results were worse than audiometric controls. From the retrospective study of these 140 revisions the AA' experience is that the stapedectomy revision offers no major risk for the inner ear.

[Calcium phosphates in otologic surgery. III. The role of fibrin glue in the integration of calcium phosphate implants. Experimental study]. / Fosfatos cálcicos en la cirugía otológica. III. El papel de la cola de fibrina en la integración de implantes de fosfato cálcico. Estudio experimental.

Obliteration of the mastoid cavity has been realized with calcium phosphates associated to heterologous fibrin glue in otologic surgery. 22 artificially created epitympanic and 65 femoral defects in 22 rabbits were closed by means of dense or porous granulates of hydroxyapatite with homologous fibrin glue. Follow-up was for three weeks to 6 months. Osteo-integration of the implants was significantly delayed in the first weeks, comparing the integration of the same phosphates without fibrin glue.

[Calcium phosphates in otological surgery. II. The bony integration of calcium phosphates. An experimental study]. / Fosfatos cálcicos en la cirugía otológica. II. La integración ósea de implantes de fosfato cálcico. Estudio experimental.

Calcium phosphates have been proposed for obliteration of the mastoid cavity as well as TORP and PORP. Their use is based on a very good biocompatibility and host acceptance. The osseous integration of a dense and a porous hydroxyapatite is studied experimentally in artificially created epitympanic holes of rabbits. Osteoneogenesis was observed from the third week after surgery starting from the walls od the defects themselves. This had been evidenced using intravital fluorescent dyes. Porous granules showed more "osteoconductivity" in the beginning, probably due to their greater surface area. Bonding osteogenesis with both materials did not show differences after six months. No resorption was observed, excepting remodelation processes.

[Calcium phosphates in surgery of the middle ear. I. The concepts and definitions]. / Fosfatos cálcicos en la cirugía de oído medio. I. Conceptos y definiciones.

The techniques which pursue the closure of radical cavities include the use of local flaps as well as alloplastic material. Calcium phosphates are classified as "degradable" or "not degradable". The paper tries to offer an explanation why hydroxyapatite or tricalcium phosphate, mostly used calcium phosphates, may be include in both groups. The introduction in the use of alloplastic materials should serve as orientation for those who initiate and stimulate to revision of clinical results. The comparison of same calcium phosphates seems not to be possible as their preparation techniques may be completely different.

[Transoral resection of locally advanced squamous cell carcinoma of the lateral oropharynx: combination of CO2 laser microsurgery with flap reconstruction]. / Transorale Resektion lokal fortgeschrittener Plattenepithelkarzinome der Oropharynxseitenwand: Kombination der CO2-Lasermikrochirurgie mit einer primären Defektdeckung.

INTRODUCTION: Transoral laser microsurgery of locally advanced carcinomas of the lateral pharynx often results in exposure of major vessels of the neck and is accompanied by a substantial risk of intra- and postoperative bleeding. We therefore only perform these operations after external protection of neck vessels, if necessary combined with flap reconstruction. PATIENTS AND METHODS: Between October 2001 and December 2004, 11 locally advanced squamous cell carcinomas of the lateral oropharynx that reached the major vessels of the neck were treated as follows: after ipsilateral neck dissection with temporary protection of the jugular vein and carotid arteries, the neck remained open while transoral laser surgery of the primary tumor was performed. Pharyngeal defects were subsequently closed by either primary suture or a platysma myofascial flap. All patients underwent adjuvant radiotherapy. RESULTS: All primary tumors were completely resected. None of the patients required tracheotomy or placement of a percutaneous endoscopic gastrostomy tube. The mean duration of nasogastric feeding tubes was 12.7 days. In one case, the routine radiological contrast study revealed a blind cervical fistula 10 days after surgery. This healed spontaneously within 7 days. One mild postoperative hemorrhage had to be stopped by endoscopic coagulation under general anesthesia. During a mean follow-up of 19.4 months, none of the patients developed a local and/or regional recurrence. CONCLUSION: The surgical procedure described ensures sufficient protection of neck vessels during and after the transoral resection of advanced carcinomas of the pharynx. It successfully combines the advantages of minimally invasive laser microsurgery with those of flap reconstruction known from traditional surgery.

Tissue reactions to glass ceramics in the middle ear.

The bioactive glass ceramic "Ceravital" was used to fashion prostheses for the replacement of various ossicles in the middle ear. They were tested in 70 rabbit ears, where they were accepted in osseous areas without formation of surrounding fibrous tissue. Histological examinations regularly showed an osseous bond with the surrounding bony tissue. Mucous membrane covered these ossicular chain prostheses and showed no evidence of inflammatory reactions. Glass ceramic implants were also used to reconstruct the ossicular chain and the posterior wall of the outer ear canal in 100 patients. The functional results were satisfactory in all cases.