Positioning Accuracy in Otosurgery Measured with Optical Tracking

Objectives

To assess positioning accuracy in otosurgery and to test the impact of the two-handed instrument holding technique and the instrument support technique on surgical precision. To test an otologic training model with optical tracking.

Study Design

In total, 14 ENT surgeons in the same department with different levels of surgical experience performed static and dynamic tasks with otologic microinstruments under simulated otosurgical conditions.

Methods

Tip motion of the microinstrument was registered in three dimensions by optical tracking during 10 different tasks simulating surgical steps such as prosthesis crimping and dissection of the middle ear using formalin-fixed temporal bone. Instrument marker trajectories were compared within groups of experienced and less experienced surgeons performing uncompensated or compensated exercises.

Results

Experienced surgeons have significantly better positioning accuracy than novice ear surgeons in terms of mean displacement values of marker trajectories. The instrument support and the two-handed instrument holding techniques significantly reduce surgeons’ tremor. The laboratory set-up presented in this study provides precise feedback for otosurgeons about their surgical skills and proved to be a useful device for otosurgical training.

Conclusions

Simple tremor compensation techniques may offer trainees the potential to improve their positioning accuracy to the level of more experienced surgeons. Training in an experimental otologic environment with optical tracking may aid acquisition of technical skills in middle ear surgery and potentially shorten the learning curve. Thus, simulated exercises of surgical steps should be integrated into the training of otosurgeons.     

Luteinizing hormone has a stage-limited effect on preantral follicle development in vitro

Although it is known that LH receptors are present from the time of thecal differentiation, the role of LH during early follicle development is not yet clear. The effect of LH on preantral follicle development has therefore been investigated in vitro using a culture system that supports the development of intact follicles. We have previously shown that although preantral follicles 150 micrometer in diameter (2-3 granulosa cell layers) do not require LH to proceed through antral development, smaller follicles (1-2 granulosa cell layers, 85-110 micrometer in diameter) do not develop beyond the large preantral stage in the presence of only FSH and 5% mouse serum. Follicles of this size were therefore used to determine the effects of LH and serum on their development in vitro. The results showed that although FSH must be continuously present, a low concentration of LH together with a slight increase in serum concentration was necessary, specifically during the primary stage of follicle development (from 85 micrometer in diameter until the follicles had reached 150 micrometer in diameter) to induce the capacity for subsequent LH-independent rapid growth and antral development. The in vitro development of maturable oocytes with normal spindle and chromatin morphology was also supported. These results indicate that LH probably induces changes in the early differentiating thecal cells, which are critical for the completion of subsequent follicular and oocyte development.     

A case report of spontaneous opening of congenitally fused labia in a female common marmoset (Callithrix jacchus) followed by pregnancy and birth of twins

A first case of spontaneous opening of congenitally fused labia (CFL phenotype) in a captive common marmoset followed by pregnancy and birth is presented here. The occurrence of this phenotype has been previously published in captive marmosets, but so far the etiology is unknown.     

M?nnchen-überschu? bei Schwarzspechtnestlingen (Dryocopus martius)?

Zusammenfassung Von 1979 bis 1991 wurde auf einer etwa 200 km² großen Mischwaldfläche in Süddeutschland bei 445 Schwarzspechtnestlingen (140 Bruten; Alter der Jungvögel: 14 bis 20 Tage) eine Geschlechtsbestimmung vorgenommen. Das Gesamtgeschlechterverhältnis (0,92 :1 ; alle Daten von 1979 bis 1991 zusammengefaßt) sowie die Geschlechterverhältnisse der Einzeljahre wichen nicht signifikant von einem ausgeglichenen Geschlechterverhältnis ab. Eine statistische Überprüfung aller zum sekundären Geschlechterverhältnis beim Schwarzspecht vorliegenden Literaturangaben ergab ebenfalls in keinem Fall einen statistisch signifikanten Unterschied zwischen den ermittelten Geschlechterverhältnissen und einem Verhältnis von 1:1. Die mehrmals in der Literatur vertretene Meinung, bei Schwarzspechtnestlingen sei ein -Überschuß festzustellen, ist somit nicht länger haltbar.

---

Is there a surplus of males in Black Woodpecker nestlings (Dryocopus martius)?

Summary A population of Black Woodpeckers was studied in an area of about 200 km² in southern Germany from 1978 up to 1991. Once a year the nesting trees were visited to record the age and number of young and to ring the nestlings. In 1979 the sex of seven birds (two broods) was determined additionally (crown feathers showing red from tenth day in , bluish-black in — only nape is red). From 1980 onwards the young of all broods censused were sexed (445 birds; 140 broods; age of the birds: 14 to 20 days). In contrast to several studies which had pointed to a -biased secondary sex ratio in the Black Woodpecker, but corresponding to findings in various bird species sexually monomorphic in size, neither the overall sex ratio (0,92 :1 ; pooled data from 1979 to 1991) nor the ratios of single years showed any significant deviations from 1:1. Likewise, we did not find any differences between the sex ratios of Black Woodpecker nestlings reported in the literature and a balanced ratio. For these reasons it is not tenable any longer to speak about a surplus of in Black Woodpecker nestlings.

     

Inhibition of apoptosis prevents West Nile virus induced cell death

Background  

West Nile virus (WNV) infection can cause severe meningitis and encephalitis in humans. Apoptosis was recently shown to contribute to the pathogenesis of WNV encephalitis. Here, we used WNV-infected glioma cells to study WNV-replication and WNV-induced apoptosis in human brain-derived cells.     

Pharmacological activity of DTPA linked to protein-based drug carrier systems

The chelating agent diethylenetriaminepentaacetic acid (DTPA) inhibits human cytomegalovirus replication. Since chelating agents are known to exhibit anti-cancer effects, DTPA-induced cytotoxicity was evaluated in breast cancer cells (MCF-7) and neuroblastoma cells (UKF-NB-3). DTPA inhibited cancer cell growth in threefold lower concentrations compared to human foreskin fibroblasts (HFF). Antiviral and anti-cancer activity of chelating agents is caused by intracellular complexation of metal ions. DTPA, an extracellular chelator, was covalently coupled to human serum albumin (HSA) molecules, HSA nanoparticles (HSA-NP), gelatin type B (GelB) molecules, and GelB nanoparticles (GelB-NP) to increase cellular uptake. Coupling of DTPA to drug carrier systems increased its cytotoxic and antiviral activity by 5- to 8-fold. Confocal laser scanning microscope examination revealed uptake of DTPA-HSA-NP in UKF-NB-3 cells and HFF. Therefore, coupling of DTPA to protein-based drug carrier systems increases its antiviral and anti-cancer activity probably by mediating cellular uptake.     

Congenitally caused fused labia in the common marmoset (Callithrix jacchus)

In this paper, the occurrence of an external genital abnormality in female marmoset monkeys (fused labia) is discussed. This malformation was detected, for the first time, in a group of animals at the German Primate Center (GPC), Goettingen. The malformed vulva was completely sealed except for an opening of 1.5-2.5 mm around the urethra sufficient for urination. Because of this defect the animals were not able to copulate. As a consequence, the affected females were functionally infertile although they had a normal genital tract and a regular cycle. This vulvar abnormality was found in 12 females, offspring of 10 pairs in which either one or both came to the German Primate Center from two genetically related colonies in Munich, Germany, and one colony in Basel, Switzerland. The abnormality appeared to be recessive and inheritable from either parent. In pairs in which both animals were from one of the mentioned colonies, 45% of the female offspring were affected. In pairs where only one partner came from these colonies, 26% of female offspring had the malformation. These results indicate that avoidance of inbreeding, which is frequently performed in primate colonies, may reduce, but not eliminate the expression of abnormalities of genetic origin. Therefore selective breeding is required, and, in colonies where these recessive mutations are widespread, the development of genetic screening tests would be advantageous.     

Increased elongation of N-acetyllactosamine repeats in doubly glycosylated lysozyme with a particular spacing of the glycosylation sites

Lysozyme is an example of an extensively studied secretory enzyme. Glycosylated mutant human lysozyme has been used as a model in studies on the biosynthesis of N-acetyllactosamine repeats in N-linked oligosaccharides. We examined the biosynthesis of the repeats in two doubly glycosylated mutants and describe here a rapid purification and separation of singly and doubly glycosylated molecules. In one of the mutants, the elongation of the repeats is enhanced if the molecules are doubly glycosylated, but not if the carbohydrate is attached to either site individually. This enhancement is not seen in the other doubly glycosylated mutant. Since lysozyme is not structurally related to glycoproteins bearing carbohydrate with N-acetyllactosamine repeats, we propose that in multivalent substrates the synthesis of the repeats can be promoted by a proper spacing of the elongated carbohydrate antennae in addition to any role of the protein backbone.     

Combined fluorescence and photovoltage studies on chlorosome containing bacteria

Energy transfer kinetics, primary charge separation, antenna size and excitonic connectivity of photosynthetic units (PSU) in whole cells of Chloroflexus aurantiacus were studied at room temperature by ps-fluorescence and ps-photovoltage as well as by stationary fluorescence-spectroscopy and fluorescence induction measurements. The fluorescence decay kinetics measured at different wavelengths are in accordance with the currently accepted sequential energy transfer from the chlorosomes via the baseplates to the B808–866 complexes and the final trapping in the RC with time constants of 19 ± 2 ps, 40 ± 4 ps and 90 ± 9 ps, respectively. However, the quantitative analysis of fluorescence spectra and the occurrence of slow phases in the fluorescence decays reveal that in whole cells a significant fraction of BChl c in the chlorosome and of BChl a in the baseplate is unconnected. The photovoltage kinetics consisted of two electrogenic phases with time constants of 118 ± 5 ps and 326 ± 35 ps and comparable electrogenicities. The first phase is ascribed to trapping from the B808-866 complexes by P+H_A- formation and the second one to charge stabilization on a quinone acceptor. Fluorescence induction curves displayed a pronounced sigmoidicity, indicating efficient lateral energy transfer between neighbored PSUs and a dense packing of 19 reaction centers (RC) beneath one chlorosome. A quantitative analysis of the fluorescence-induction curves at different excitation wavelengths allows the estimation of pigment stoichiometries (i.e. antenna sizes): BChl c/RC 794 and B808/RC 15.     

Bone marrow and lymphocyte cytogenetics of rhesus monkeys (Macaca mulatta) treated with the clastogen mitomycin C

Rhesus monkeys (Macaca mulatta) were used to determine their effectiveness as experimental animals for different cytogenetic tests with mitomycin C (MC). The micronucleus test (MNT) and/or chromosome analysis of blood and bone marrow were made before and/or after the treatment with mitomycin C. Thus, the controls data and treated data were obtained from the same animals. With the employed methology, the micronucleus test could not be performed on living animals. Less chromosomal damage was detected in the micronucleus test of post-mortem samples than in the chromosome analysis of bone marrow. No influence by the mutagen could be observed in lymphocyte chromosomes at any of the different times of analysis. In contrast to this, bone-marrow chromosomes seemed to be highly affected by mitomycin C at day 1, 2 and 3 after injection. However, before treatment and at day 14, 16 and 17 after treatment there was no visible increase in chromosomal aberration in bone marrow.