[Experience with orbital implants in particular with porous hydroxyapatite materials]. / Erfahrungen mit Orbitaimplantaten, insbesondere mit porösen Hydroxylapatitmaterialien.

PURPOSE: Various materials have been developed since the first implantation of a hydroxyapatite sphere in 1985. They are similar to the porous basic structure and imitate the biological behavior of coralline implants. This article presents own clinical experience with hydroxyapatite implants from 1993 to 2003 and compares own results and other porous orbital implants in the international scientific literature. RESULTS: The original hydroxyapatite implant is well tolerated and implant extrusion is rare. A retrospective analysis of 357 patients regarding this complication shows an extrusion rate of 2.6% over 10 years. The subjective positive tolerance of 71.2% corresponds to the results of international studies. After several stages of development the synthetic product (FCI3) is now comparable with the original product with regard to operative complications and subjective compatibility. Both orbital implants should be used with a protective covering to avoid premature extrusion and to facilitate suturing the extraocular muscles anterior. When using material from humane donors the material must be guaranteed to be completely sterile. The use of vicryl as an orbital plomb wrapping leads to contradictory reports in the literature. Hydroxyapatite ceramics in combination with silicone india rubber represent an alternative to the materials listed above and in this case a wrapping of the orbital plomb is unnecessary. Spherical orbital implants made of aluminum oxide (bioceramic implant) are an alternative to corraline hydroxyapatite implants. Because of their porous,crystalline structure bioceramic implants vascularize well. Porous polythylene orbital implants,which are not available in Germany, are economical, but due to their porosity and vascularization properties they are not comparable with pure hydroxyapatite or hydroxyapatite ceramics. FUTURE VIEW: The dynamic development of the infant anopthalmus adapted to the size growth of the orbita and the exact volume replenishment of the adult orbita cannot yet be fulfilled with the presently available porous hydroxyapatite materials and is the subject of future research.

Phosphorylation of uridine and cytidine nucleoside analogs by two human uridine-cytidine kinases.

Uridine-cytidine kinases (UCK) have important roles for the phosphorylation of nucleoside analogs that are being investigated for possible use in chemotherapy of cancer. We have cloned the cDNA of two human UCKs. The approximately 30-kDa proteins, named UCK1 and UCK2, were expressed in Escherichia coli and shown to catalyze the phosphorylation of Urd and Cyd. The enzymes did not phosphorylate deoxyribonucleosides or purine ribonucleosides. UCK1 mRNA was detected as two isoforms of approximately 1.8 and approximately 2.7 kb. The 2.7-kb band was ubiquitously expressed in the investigated tissues. The band of approximately 1.8 kb was present in skeletal muscle, heart, liver, and kidney. The two isoforms of UCK2 mRNA of 1.2 and 2.0 kb were only detected in placenta among the investigated tissues. The genes encoding UCK1 and UCK2 were mapped to chromosome 9q34.2-9q34.3 and 1q22-1q23.2, respectively. We tested 28 cytidine and uridine nucleoside analogs as possible substrates of the enzymes. The enzymes phosphorylated several of the analogs, such as 6-azauridine, 5-fluorouridine, 4-thiouridine, 5-bromouridine, N(4)-acetylcytidine, N(4)-benzoylcytidine, 5-fluorocytidine, 2-thiocytidine, 5-methylcytidine, and N(4)-anisoylcytidine. The cloning and recombinant expression of the two human UCKs will be important for development of novel pyrimidine ribonucleoside analogs and the characterization of their pharmacological activation.

[Laser canaliculoplasty]. / Lasercanaliculoplastik.

BACKGROUND: Laser canalicular plastic surgery using the erbium-YAG laser is a new method for treating canaliculus stenosis. We compared results of this method with those of conventional surgical operations on canaliculi. PATIENTS AND METHODS: Between 1996 and 1998 a total of 44 cases of symptomatic canaliculus stenosis were treated by laser. An erbium-YAG laser with a maximum power of 100 mJ was used in conjunction with a sapphire fiber 3 cm long and 325 microns in diameter. Endoscopic diagnosis of the other parts of the lacrimal passage was carried out before and after laser treatment and after tubular intubation. After an average of 12 months the results were assessed via questionnaires and follow-up examinations. RESULTS: The success rate for reducing epiphora was 67%. Overall 86% of patients reported an improvement in canaliculus communis stenosis. CONCLUSIONS: Laser canalicular plasty as minimally invasive surgical treatment is an excellent surgical method for treating point-focal, noninflammatory canalicular stenosis.

[Long-term results of implantation of hydroxylapatite as artificial eye]. / Langzeitresultate mit der Implantation von Hydroxylapatit als Bulbusersatz.

BACKGROUND: Since its first implantation as an eyeball replacement in the United States in 1985, hydroxyapatite has been rarely used as an orbital implant in Germany. The aim of the study was to collect data on long-term tolerance, postoperative complications and the cosmetic end results. PATIENTS AND METHODS: In the spring of 1997, 52 patients underwent a follow-up examination at our hospital. The average post-operative follow-up period was 23 (12-41) months. RESULTS: The subjective tolerance was considered good by 3/4 of the patients. In the comparison of position and prominence of the artificial eye, 8 patients achieved complete equalization. As regards defective lid position, 8 patients had a ptosis, 6 an ectropium, and there was one case of entropium. Changes in conjunctiva stretched from muciferous secretion to follicular squamous hyperplasia. There was no case of implant extrusion in the series examined. With reference to the method of implantation, far superior motility was observed in primary implantations. Statistically significant motility differences could not be shown regarding muscle attachment because of the small number of the cases. CONCLUSIONS: In the series examined, hydroxyapatite proved to be a generally well-tolerated orbital implant with few postoperative complications and good motility. Primary implantation with attachment of all six eye muscles gave the best results.

Conserved gene structure and transcription factor sites in the human and mouse deoxycytidine kinase genes.

Deoxycytidine kinase (dCK) phosphorylates several anti-cancer and anti-viral nucleoside analogs. The enzyme is predominantly expressed in lymphoid tissues regulated by an unknown mechanism. We have cloned and sequenced the 20 kbp mouse dCK gene and approximately 1.7 kbp of the 5' flanking regions of both the human and mouse dCK genes. Five major inter-species conserved motifs were identified in the 5' region including the transcription initiation region, an SP1 site and two closely located putative octamer transcription factor sites. Luciferase reporter experiments showed that the human dCK 5' region efficiently initiated transcription but no tissue regulatory element could be identified.

Pharmacokinetics of melphalan in isolated limb perfusion.

The pharmacokinetics of melphalan was studied by sampling of tissue and plasma in 72 rats that underwent isolated hyperthermic limb perfusion under different conditions. A miniaturized extracorporeal circulation system for small animals was used for perfusion of the rat hindlimb. Melphalan levels (L-phenylalanine mustard, L-PAM) were determined by high-performance liquid chromatography (HPLC). The temperature of the perfusate plasma and tissue, pH, administration method, and flow rate were modified and compared with regard to their influence on pharmacokinetic parameters. The highest tissue penetration of melphalan was observed under the following conditions: (a) pH range of the perfusate plasma between 7.3 and 7.7 (physiological environment), (b) temperature range of the perfusate from 40 degrees to 41.5 degrees C (destruction of cellular carrier systems at higher temperatures and increased inactivation by hydrolysis of melphalan above 41.5 degrees C), (c) application of melphalan as a single dose into the reservoir of the extracorporeal circuit (optimal tissue penetration), and (d) reduced perfusate flow (prolonged contact time between perfusate and tissue).