Instrument flight to the inner ear.

Surgical robot systems can work beyond the limits of human perception, dexterity and scale making them inherently suitable for use in microsurgical procedures. However, despite extensive research, image-guided robotics applications for microsurgery have seen limited introduction into clinical care to date. Among others, challenges are geometric scale and haptic resolution at which the surgeon cannot sufficiently control a device outside the range of human faculties. Mechanisms are required to ascertain redundant control on process variables that ensure safety of the device, much like instrument-flight in avionics. Cochlear implantation surgery is a microsurgical procedure, in which specific tasks are at sub-millimetric scale and exceed reliable visuo-tactile feedback. Cochlear implantation is subject to intra- and inter-operative variations, leading to potentially inconsistent clinical and audiological outcomes for patients. The concept of robotic cochlear implantation aims to increase consistency of surgical outcomes such as preservation of residual hearing and reduce invasiveness of the procedure. We report successful image-guided, robotic CI in human. The robotic treatment model encompasses: computer-assisted surgery planning, precision stereotactic image-guidance, in-situ assessment of tissue properties and multipolar neuromonitoring (NM), all based on in vitro, in vivo and pilot data. The model is expandable to integrate additional robotic functionalities such as cochlear access and electrode insertion. Our results demonstrate the feasibility and possibilities of using robotic technology for microsurgery on the lateral skull base. It has the potential for benefit in other microsurgical domains for which there is no task-oriented, robotic technology available at present.

[Methaemoglobinaemia in a child treated with Emla(®) cream: circumstances and consequences of overdose]. / Méthémoglobinémie après application de crème Emla(®) chez un enfant : circonstances et conséquences d'un surdosage.

BACKGROUND: Emla(®) cream, a mixture of two local anaesthetics (prilocaine 2.5%, lidocaine 2.5%) has a good benefit-risk profile. However, methaemoglobinaemia can occur, especially when the cream is applied in excessive amounts or over long periods. PATIENTS AND METHODS: The authors report a case of seizure and respiratory disturbances (MetHb=20.1%) after excessive application of Emla(®) (30g) for curettage of molluscum contagiosum in a young girl with eczema. The patient's clinical condition improved after withdrawal of the cream and administration of methylene blue, and she returned home on day two. DISCUSSION: This new case of methaemoglobinaemia in a child following application of Emla(®) cream highlights the importance of strict compliance with the instructions for use of this medicinal product.

Telomere dynamics: the means to an end.

Telomeres are among the most important structures in eukaryotic cells. Creating the physical ends of linear chromosomes, they play a crucial role in maintaining genome stability, control of cell division, cell growth and senescence. In vertebrates, telomeres consist of G-rich repetitive DNA sequences (TTAGGG)n and specific proteins, creating a specialized structure called the telosome that through mutual interactions with many other factors in the cell give rise to dynamic regulation of chromosome maintenance. In this review, we survey the structural and mechanistic aspects of telomere length regulation and how these processes lead to alterations in normal and immortal cell growth.

Molecular mechanisms involved in the antiproliferative action of protein tyrosine phosphatase inhibitor potassium bisperoxo(1,10-phenanthroline)oxovanadate.

Potassium bisperoxo(1,10-phenanthroline)oxovanadate, bpV(phen), a powerful protein phosphotyrosine phosphatase inhibitor and a potent insulinomimetic, influenced three fundamental cellular processes in HL-60 human leukemic cells: 1) inhibition of proliferation, 2) induction of differentiation and 3) apoptotic cell death. In the presence of micromolar concentrations of bpV(phen) cell number and DNA synthesis decreased progressively with time of incubation. A single treatment with bpV(phen) (3 microM) activated a differentiation program; after 6 days of incubation 82% of cells were differentiated, but differentiation started already within the first 24 h. Concentrations of 5-10 microM bpV(phen) caused the characteristic DNA ladder pattern, starting after 4.5 h. Differentiation in HL-60 cells appear to be associated with activation of extracellular signal-regulated kinase while apoptosis is connected with phosphorylation and activation of both extracellular signal-regulated kinase and c-Jun N-terminal kinase in a concentration and time-dependent manner. The antiproliferative and apoptotic action of bpV(phen) could be exploited in combination chemotherapy in leukemia.

Genetic factors in dilated cardiomyopathy.

Recent studies have demonstrated that genetic factors are likely to play a major role in the pathogenesis of idiopathic dilated cardiomyopathy (IDC). In clinical surveys, a familial trait has been demonstrated in 20 to 30% of idiopathic dilated cardiomyopathy patients (familial dilated cardiomyopathy). Molecular genetic studies have confirmed the clinical hypothesis of genetic heterogeneity in familial dilated cardiomyopathy, and are currently producing relevant advances in the understanding of this disease. The autosomal dominant form is considered to be the most frequent form of inherited idiopathic dilated cardiomyopathy. After the exclusion of a large series of candidate genes, the first familial dilated cardiomyopathy gene has been mapped to the long arm of chromosome 9. A second locus has been found on chromosome 1. Moreover, in two large families, characterized by a peculiar form of conduction delays and later development of myocardial dysfunction, the disease loci have been mapped to chromosome 1 and 3, respectively. The identification of the disease genes is in progress. In families with X-linked dilated cardiomyopathy, the disease gene has been identified as the dystrophin gene. The 5' end of the gene appears to be the critical region for the development of dilated cardiomyopathy without clinical evidence of muscle dystrophy. Furthermore, other cytoskeletal proteins, such as adhalin, could be involved in the pathogenesis of familial dilated cardiomyopathy. In familial right ventricular cardiomyopathy (or arrhythmogenic right ventricular dysplasia) characterized by isolated or prevalent right ventricular involvement, three different disease loci have been identified so far: two localized on the long arm of chromosome 14 and one on chromosome 1. The disease genes are still unknown and are currently under investigation. The study of the genetic factors at the molecular level is starting to elucidate the pathogenetic mechanisms of idiopathic dilated cardiomyopathy. These findings will also have relevant clinical and therapeutic implications.

Papillomavirus genomes in human cervical carcinoma: analysis of their integration and transcriptional activity.

Eighty-four biopsies derived from cervical tissues were analyzed for the presence of human papillomavirus (HPV) DNA types 6, 16 and 18 using Southern blot hybridization. HPV 6 was found in none of the cervical biopsies, and HPV types 16 and 18 were found in 44% of them. The rate of HPV 16/18 positive samples increased proportionally to the severity of the lesion. In normal tissue there were no positive samples, in mild and moderate dysplasias HPV 16/18 was present in 20% and in severe dysplasias and invasive carcinomas in 37 and 50%, respectively. In biopsies from 13 cases with squamous cell carcinoma of the uterine cervix and CIN III lesions HPV 16 was integrated within the host genome. It was concluded that the virus could be integrated at variable, presumably randomly selected chromosomal loci and with different number of copies. Transcription of HPV 16 and 18 was detected in one cervical cancer and in HeLa cells, respectively. These results imply that HPV types 16 and 18 play an etiological role in the carcinogenesis of human cervical epithelial cells.

Resistance of human larynx carcinoma cells to cisplatin, gamma-irradiation and methotrexate does not involve overexpression of c-myc or c-Ki-ras oncogenes.

In our previous study, we achieved resistance to cisplatin or vincristine (VCR) by repeated treatments of human larynx carcinoma HEp2 cells with these drugs. Resistant cells were cloned and four clones were selected: CA3 and VA3 clones were selected from cells acutely treated with cisplatin or VCR, while CK2 and VK2 cells were selected from cells chronically treated with cisplatin and VCR, respectively. The aim of this study was to examine whether the development of resistance to cisplatin and vincristine changes the expression of c-myc and c-Ki-ras oncogenes and to determine whether there is a correlation between the expression of these oncogenes and the sensitivity of selected clones to cisplatin, methotrexate and gamma-rays. The cell sensitivity to cisplatin, methotrexate and gamma-rays was determined on the basis of the clonogenic survival assay. The expression of c-myc and c-Ki-ras oncogenes was examined by the use of RNA dot blot and Northern blot analyses. The results show that the development of resistance to selected drugs does not alter the expression of either c-myc or c-Ki-ras oncogene. CA3 and CK2 clones were resistant to cisplatin, while the vincristine resistant clones VA3 and VK2 became sensitive to this drug. The sensitivity of resistant clones to gamma-rays varied. CA3 cells were resistant, VA3 and VK2 cells sensitive, while CK2 cells exhibited the same sensitivity to gamma-rays as did the parental cells. All four clones tested became cross-resistant to methotrexate. We can conclude that development of resistance to cisplatin and vincristine does not alter the expression of c-myc or c-Ki-ras oncogene. We did not find any correlation between expression of these oncogenes and the sensitivity to cisplatin, methotrexate or gamma-rays.

Multiple fractions of gamma rays do not induce overexpression of c-myc or c-Ki-ras oncogenes in human cervical carcinoma cells.

Multiple fractions of gamma rays (0.5 Gy daily, 30 fractions) had previously been found to change the sensitivity of human cervical carcinoma HeLa cells to anticancer drugs. Preirradiated cells became resistant to cisplatin, methotrexate and vincristine, but retained the same sensitivity to gamma rays and ultraviolet light. Some mechanisms involved in resistance of preirradiated cells to cisplatin and vincristine were determined, i.e. the increased levels of metallothioneins and increased expression of plasma membrane P glycoprotein. As recent reports indicated that the resistance to cisplatin and ionizing radiation may involve expression of oncogenes, we examined whether multiple fractions of gamma rays can change the expression of c-myc and c-Ki-ras oncogenes in HeLa cells and determined whether there is a correlation between expression of these oncogenes and sensitivity of preirradiated cells to cisplatin and gamma rays. The expression of c-myc and c-Ki-ras oncogenes were examined by the use of DNA dot blot, RNA dot blot and Northern blot analyses. The results show that preirradiation did not induce either amplification or elevated expression of c-myc or c-Ki-ras oncogenes. Further, there is no correlation between expression of c-myc and c-Ki-ras oncogenes and the acquired resistance to cisplatin.

Induction of plasminogen activator by N-methyl-N'-nitro-N-nitrosoguanidine in mer+ and mer- human tumour cell strains.

Plasminogen activator (PA) synthesis in alkylation DNA repair deficient (mer-) and proficient (mer+) human tumour cell strains exposed to an alkylating agent, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), has been studied. MNNG enhanced the production of PA in mer- cell strains (U87MG, A1235, A1336, A172), but not in mer+ strains (TE85, HT29, U178MG, A288), which reactivated and supported well the growth of alkylation damaged adenovirus 3. Several mer+ strains (A549 and A2182), which are highly susceptible to killing by MNNG, produced moderately elevated enzyme levels after alkylating treatment. In the alkylation repair defective strains, enhanced production of both intra and extracellular PA occurred with 2-10 microM MNNG causing a 20-40% inhibition of [3H]thymidine incorporation. Maximum PA induction was observed 30-48 h after alkylation treatment and the levels of enzyme produced were 5-10 times as high as those of untreated control levels. As shown by electrophoretic analysis, MNNG enhances in mer- cells the synthesis of 40,000-50,000 Dalton of human urokinase type PA which is also present in lower amounts in untreated cells. This alkylation induced PA production by mer- cells required RNA and protein synthesis because it did not occur in the presence of actinomycin D or cycloheximide. PA induction by MNNG occurred throughout the cell cycle of synchronized mer- cells indicating that blockage of DNA synthesis is not responsible for enzyme induction and that it may result from DNA transcription on a damaged template. It was thus concluded that PA induction is causally associated with deficient DNA repair, which makes it useful as a sensitive assay for identification of alkylation repair deficient cell strains.