Biomedical subjects

J Mühling

Publications and source records attributed to J Mühling.

At least 19 recordsLinked to original sources

PubMed2006

Pathways involved in alanyl-glutamine-induced changes in neutrophil amino- and alpha-keto acid homeostasis or immunocompetence.

We examined the effects of DON [glutamine-analogue and inhibitor of glutamine-requiring enzymes], alanyl-glutamine (regarding its role in neutrophil immunonutrition) and alanyl-glutamine combined with L-NAME, SNAP, DON, beta-alanine and DFMO on neutrophil amino and alpha-keto acid concentrations or important neutrophil immune functions in order to establish whether an inhibitor of *NO-synthase [L-NAME], an *NO donor [SNAP], an analogue of taurine and a taurine transport antagonist [beta-alanine], an inhibitor of ornithine-decarboxylase [DFMO] as well as DON could influence any of the alanyl-glutamine-induced effects. In summary, irrespective of which pharmacological, metabolism-inhibiting or receptor-mediated mechanisms were involved, our results showed that impairment of granulocytic glutamine uptake, modulation of intracellular glutamine metabolisation and/or de novo synthesis as well as a blockade of important glutamine-dependent metabolic processes may led to significant modifications of physiological and immunological functions of the affected cells.

Adult↗

PubMed2006

Nitric oxide and polyamine pathway-dependent modulation of neutrophil free amino- and alpha-keto acid profiles or host defense capability.

We have examined the effects of N(omega)-nitro-L-arginine-methylester-hydrochloride [L-NAME; inhibitor of nitric oxide synthase], S-nitroso-N-acetyl-penicillamine [SNAP; nitric oxide donor], alpha-difluoro-methyl-ornithine [DFMO; inhibitor of ornithine decarboxylase] arginine or ornithine as well as the combination of arginine or ornithine with L-NAME, SNAP or DFMO on intracellular free amino- and alpha-keto acid profiles and the immune function markers superoxide anion and hydrogen peroxide generation as well as released myeloperoxidase activity in neutrophils (PMN). Although the underlying mechanisms still remain unclear, we believe from our results that nitric oxide as well as polyamine-dependent pathways are involved in the signal transmission of free radical molecule, beneficial nutritional therapy or maleficient pharmacological stress-induced alterations in PMN nutrient composition. Relevant changes in intragranulocyte free amino- and alpha-keto acid homeostasis and metabolism, especially, may be one of the determinants in PMN nutrition that positively or negatively influences and modulate neutrophil host defence capability and immunocompetence.

Adult↗

PubMed2006

Piezosurgery--a new safe technique in cranial osteoplasty?

All surgical interventions on the neurocranium bear the risk of injury of the dura mater and development of a cerebrospinal fluid fistula. Therefore, despite careful preparation, damage to the dura mater cannot always be omitted. Especially after surgery and in patients with increased intracranial pressure (craniosynostoses) there is a high risk of perforating the dura. In this article a new surgical technique for osteotomy (Piezosurgery) that avoids perforation of the dura is presented. Ultrasonic microvibrations allow a selective cut of only mineralized structures without damage to the soft tissue. Even in case of accidental contact the dura remains undamaged. This advantage is also useful for bone splitting, to separate the tabula externa from the tabula interna in situ, without any risk of dura perforation even in case of the very thin bones in an infantile skull. The present work shows the applicability of piezoelectric surgery in high-risk patients after osteotomy, avoiding perforation of the dura mater.

Brain Injuries↗

PubMed2006

Image-to-patient registration techniques in head surgery.

Frame-based stereotaxy was developed in neurosurgery at the beginning of the last century, evolving from atlas-based stereotaxy to stereotaxy based on the individual patient's image data. This established method is still in use in neurosurgery and radiotherapy. There have since been two main developments based on this concept: frameless stereotaxy and markerless registration. Frameless stereotactic systems ('navigation systems') replaced the cumbersome stereotactic frame by mechanically and later also optically or magnetically tracked instruments. Stereotaxy based on the individual patient's image data introduced the problem of patient-to-image data registration. The development of navigation systems based on frameless stereotaxy has dramatically increased its use in surgical disciplines other than neurosurgery, but image-guided surgery based on fiducial marker registration needs dedicated imaging for registration purposes, in addition to the diagnostic imaging that might have been performed. Markerless registration techniques can overcome the resulting additional cost and effort, and result in more widespread use of image-guided surgery techniques. In this review paper, the developments that led to today's navigation systems are outlined, and the applications and possibilities of these methods in the field of maxillofacial surgery are presented.

Cephalometry↗

PubMed2006

[Malposition of the orbita from the surgical point of view].

The individual appearance of a person is mainly determined by the head and, in particular, by the eyes. The orbita exerts a decisive influence on the harmony of the face. Anomalies of the neuro- and viscerocranium have varying impact on the orbits as well as on the structures of the bulb, resulting in dysmorphia or dystopia of the orbits which, in turn, lead to corresponding functional impairments. Premature craniosynostoses, representing the most frequent craniofacial malformation, may have an influence on the region of the orbita in different manner. Symptomatics depend on localisation, number and severity of the synostoses. Main symptoms are uni- or bilateral exophthalmus as well as hypo- or hypertelorism. The deformation of the patients is not only a "cosmetic problem" but often also a barrier to social communication with all consequent impairments of the patient's development. Sometimes it is even the only reason for a mental retardation of the child. Apart from augmentation of the intracranial volume, the main aim of corrective surgery, therefore, is normalisation of the patient's appearance. There are various surgical procedures for operative correction. However, therapy is not only directed towards the orbita but has to be integrated into the overall concept for therapy of the disease. In this article we show the surgical approaches for the treatment of orbital malformations caused by various craniofacial malformations, using clinical examples.

Eye Abnormalities↗

PubMed2005

Relationship of taurine and other amino acids in plasma and in neutrophils of septic trauma patients.

Recently, an interdependency of plasma taurine and other amino acids as well as metabolic and clinical variables implicating therapeutic options was reported. This result may be an indication that plasma taurine levels are directly related to intracellular levels. Therefore, the aim of this study was to analyse the possible relationship between taurine levels in plasma and in neutrophils, the relationship to other amino acids, and variables quantifying metabolic impairment and severity of sepsis in multiple trauma patients developing sepsis. After multiple trauma taurine decreased significantly in plasma in thirty-two patients as well as within the neutrophil and does not recover in sepsis. Lower individual levels in the neutrophil did not follow lower individual levels in plasma and no correlation of taurine in plasma and in the neutrophils could be observed. In sepsis, only plasma showed an interdependency of taurine, aspartate, and glutamate. No association between taurine plasma or intracellular levels and SOFA score as indicator for severity of sepsis or metabolic variables was observed. After multiple trauma and in sepsis, taurine uptake in cells (which is regulated in different ways), and intracellular taurine (which serves e.g. as an osmolyte) can be influenced. Therefore a prediction of the neutrophil taurine pool seems not fully possible from taurine plasma levels. Intracellular taurine has some unique properties explaining the missing interdependency despite some similarities in osmoregulation and metabolic interactions to other amino acids. The association of taurine, aspartate, and glutamate in plasma cannot be simply transferred to the neutrophils intracellular level. The clinical meaning of the plasma correlation remains unclear. A dependency of plasma and neutrophil taurine to severity of sepsis and to metabolic variables seems not possible because of the multifactorial pathophysiology of sepsis.

Adult↗

PubMed2005

Alterations in neutrophil (PMN) free intracellular alpha-keto acid profiles and immune functions induced by L-alanyl-L-glutamine, arginine or taurine.

The objective of this study was to determine the dose as well as duration of exposure-dependent effects of L-alanyl-L-glutamine, arginine or taurine on polymorphonuclear neutrophil (PMN) free alpha-keto acid profiles and, in a parallel study, on PMN immune functions. Exogenous L-alanyl-L-glutamine significantly increased PMN alpha-ketoglutarate, pyruvate PMN superoxide anion (O2-) generation, hydrogen peroxide (H2O2) formation and released myeloperoxidase (MPO) activity. Arginine also led to significant increases in alpha-ketoglutarate, pyruvate, MPO release and H2O2 generation. Formation of O2- on the other hand was decreased by arginine. Incubation with taurine resulted in lower intracellular pyruvate and alpha-ketobutyrate levels, decreased O2- and H2O2 formation and a concomitant significantly increased MPO activity. We therefore believe that considerable changes in PMN free-alpha-keto-acid profiles, induced for example by L-alanyl-L-glutamine, arginine or taurine, may be one of the determinants in cell nutrition that considerably modulates the immunological competence of PMN.

Adult↗

PubMed2005

[Markerless patient registration. A new technique for image-guided surgery of the lateral base of the skull].

BACKGROUND: Markerless patient registration is a new procedure that may reduce logistical efforts and possibly also the radiation load on the patients prior to a computer-assisted intervention. Congruent surfaces, such as bone surfaces or skin surfaces, represented in a data set and in the surgical site, can be overlapped with the help of surface matching. Hitherto, these techniques were performed by using the periorbital and frontal skin of the face. The present clinical study assessed the usability of the auricle as a skin structure for markerless patient registration in lateral skull base surgery. PATIENTS AND METHODS: The periauricular precision of the navigation system SSN was investigated clinically in ten patients. Radiopaque registration markers in the periauricular region served as a target in order to evaluate the markerless registration method. RESULTS: Exact patient registration failed in five cases due to temporary deformation of the auricle caused by the head support during CT imaging. An excellent patient registration (mean target registration error = 0.9+/-0.2 mm) was found as long as the auricles had not been temporarily deformed during CT imaging. CONCLUSION: Laser-scan registration of the auricle reduces logistics in image-guided lateral skull base surgery. The problem of temporary deformation of the auricle during CT imaging might be solved by an appropriate opening in the head support at the level of the auricles.

Humans↗

PubMed2005

An augmented reality system for image-guided surgery.

The introduced new developed navigation system is a High Intensity Approach Light System for augmented reality in image-guided surgery. The surgeon follows the projected approach lights with his ordinary surgical instruments. Thus, tracked instruments are not necessary with this system.

Humans↗

PubMed2005

[A new method for computer-assisted orbitotomies].

BACKGROUND: Surgical planning and tumor margins from preoperative image data sets can be transferred to the surgical site by use of computer-assisted navigation systems. Usually registration markers are placed prior to image data acquisition in order to correlate the patient's preoperative image data set with his/her position in the operating room. Pointers are commonly used for navigation, and the position of the pointer within the surgical site is compared to its position within the image data set. With a new navigation system, patient registration can be performed without registration markers. Tumor margins and osteotomy lines can be projected onto the surgical site. MATERIALS AND METHODS: With the new navigation system, which has been developed by the Sonderforschungsbereich 414 of the Deutsche Forschungsgemeinschaft, markerless patient registration is performed using the contours of the patient's face. A scanner is mounted above the operating table, which detects the surface of the surgical site intraoperatively. Osteotomy lines and tumor margins are projected onto this surface using an intense beamer. The procedure is illustrated for a patient with a meningeal tumor of the orbit. RESULTS: Patients can be registered with an accuracy of 1 mm. Pointers are not required to transfer the data on the surgical site. Furthermore, monitors are no longer required, since the information is projected directly on the patient's surface. CONCLUSIONS: Surgical planning and tumor margins can exactly be visualized within the surgical site. Ergonomics are especially improved for navigated orbitotomies via a coronal approach.

Adult↗

PubMed2005

[Sepsis and multiple organ failure - update of current therapeutic concepts].

Severe sepsis with multiple organ dysfunctions is still the leading cause of death in non-cardiac intensive care units. The incidence is expected to rise in the future due to the growing number of older and immuno-compromized patients, the use of invasive procedures, and an increase in the percentage of aggressive or resistant microorganisms. Despite the enormous investment in critical care resources, mortality of severe sepsis remaines on a high level and ranges from 28 - 50 %. Based on the disappointing experiences with anti-inflammatory strategies, we now realize that sepsis is more than just inflammation. The new therapeutic approaches take account of this more sophisticated view of pathophysiologic changes, resulting in the modulation of the coagulation in combination with an improvement of the ICU-management of organ dysfunctions. This review discusses the therapeutic concepts, reported es exciting new interventions in the ICU setting to decrease the inacceptable high mortality in patients with severe sepsis.

Catecholamines↗

PubMed2005

Laser surface registration for lateral skull base surgery.

OBJECTIVE: Logistics in the run-up to computer-assisted lateral skull base intervention can be reduced by markerless registration methods. So far, only the facial skin surface but not the skin surface that was near to the lateral skull base was used for markerless patient registration. The present study was designed to evaluate whether the auricles may serve as an accurate spatial reference for markerless patient registration in image-guided lateral skull base surgery. STUDY DESIGN: In a prospective clinical study, the precision of markerless patient registration was checked by using periauricular evaluation markers and additional distant oral evaluation markers that served as targets for the infrared pointer of a navigation system. Ten patients with cranial tumors, bony malformations, or foreign bodies who were planned for image-guided surgery were selected. Markerless patient registration was performed by laser-scanning with the SSN++ navigation system. RESULTS: Based on the auricle, a high accuracy (mean target detection error tde = 0.9 mm +/- s = 0.3 mm) was achieved in markerless patient registration as long as the auricle was not deformed during CT imaging or during laser scanning. However, the conventional CT acquisition with a head support caused temporary auricular deformations in half of the patients, which made a precise laser-scan registration impossible. CONCLUSIONS: Automated laser registration of the auricle reduces the logistical input in connection with computer-assisted lateral skull base surgery, ensuring the accuracy that has been achieved up to now with marker-based methods. Constantly good results can be achieved if the head support of the computer tomograph has an appropriate opening at the level of the auricles in order to avoid auricular deformations during CT acquisition.

Adult↗

PubMed2005

Robot-assisted craniotomy.

In the Special Research Centre 414 of the German Research Funding (DFG, Bonn) a system for robot-assisted cranial surgery was developed. It is designed for the accurate and safe execution of craniotomies and repositioning of bone pieces. The system is intended for use in the surgical therapy of craniosynostosis. Preoperatively, CT imaging is performed. In a computerized planning system the position and shape of the intended craniotomy is intuitively planned on a virtual model of the patient's skull. Intraoperatively, after conventional removal of the covering soft tissue, the robot performs the craniotomy autonomously. Extensive testing in phantom studies and animal tests confirmed the reliability and accuracy of the system. A thorough risk analysis of the system was performed. In this paper, the first clinical use of the system on a patient is described and the clinical importance is discussed.

Bone Cysts↗

PubMed2005

Geometric accuracy of the NewTom 9000 Cone Beam CT.

OBJECTIVES: To determine the geometric accuracy of digital volume tomograms to assess their usability for implant planning. METHODS: A measuring object with 216 measuring points, whose geometry is exactly known, is X-rayed with a NewTom 9000 cone beam scanner; thereafter the geometry of the volume tomogram of the object is compared with the original body. RESULTS: Considering all three coordinate axes, geometric mean deviations of 0.13 +/- 0.09 mm with a maximum deviation of 0.3 mm were determined. These geometric deviations are below the resolution power of the volume tomograph. CONCLUSION: The digital volume tomographies of NewTom 9000 present images which are geometrically correct and, from a geometrical point of view, suitable for three-dimensional implant planning.

Dental Implantation, Endosseous↗

PubMed2004

Benzodiazepine receptor-dependent modulation of neutrophil (PMN) free amino- and alpha-keto acid profiles or immune functions.

We have examined the effects of midazolam, Ro 5-4864 (agonist for "peripheral" [p] benzodiazepine receptors [BR]), PK 11195 (antagonist for pBR), flumazenil (antagonist for "central" BR), naloxone (antagonist for opiate receptors) and the combination of midazolam and Ro 5-4864, PK 11195, flumazenil or naloxone on intracellular amino- and alpha-keto acids and the immune function markers superoxide anion (O(2)(-)), hydrogen peroxide (H(2)O(2)) and released myeloperoxidase (MPO) activity in neutrophils (PMN). Only midazolam and Ro 5-4864 led to significant changes in the dynamic PMN free amino- and alpha-keto acid pools. Concerning PMN immune function markers, midazolam and Ro 5-4864 significantly decreased O(2)(-) and H(2)O(2) formation and released MPO. When midazolam and Ro 5-4864 were applied together they appeared to act additively. Pre-incubation with PK 11195 partially neutralized the midazolam effects whereas flumazenil or naloxone showed no effects. We therefore believe that pBR are involved in the signal transmission of anesthetic-induced cellular metabolic changes in PMN.

Adult↗

PubMed2004

Effects of ornithine on neutrophil (PMN) free amino acid and alpha-keto acid profiles and immune functions in vitro.

The objective of this study was to determine the effects of ornithine on polymorphonuclear leucocyte (PMN) free amino- and alpha-keto acid profiles, superoxide anion (O2-) generation, hydrogen peroxide (H2O2) formation and released myeloperoxidase activity (MPO). Exogenous ornithine significantly increased PMN asparagine, glutamine, aspartate, glutamate, arginine, citrulline, alanine, alpha-ketoglutarate and pyruvate as intracellular ornithine increased. Concerning PMN immune function markers ornithine increased H2O2-generation and MPO activity while O2- -formation was decreased. We believe therefore that ornithine is important for affecting PMN "susceptible free amino- and alpha-keto acid pool" although the mechanisms are not yet clear. This may be one of the determinants in PMN nutrition considerably influencing and modulating PMN host defense capability.

Adult↗

PubMed2004

Automated laser registration in image-guided surgery: evaluation of the correlation between laser scan resolution and navigation accuracy.

Markerless patient registration based on the facial skin surface makes logistics prior to image-guided surgery much easier, as it is not necessary to place and measure registration markers. A laser scan registration of the surgical site takes the place of conventional marker-based registration. In a clinical study, the stability and accuracy of markerless patient registration was evaluated in 12 patients. Intraoral titanium markers served as targets for the infrared-pointer of the navigation system in order to check the accuracy of the markerless registration process. The correlation between laser scan resolution and navigation accuracy was checked using seven different laser scan resolutions (a cloud of 300,000 laser scan points down to 3750 laser scan points of the surgical site). The markerless patient registration was successful as long as high laser scan resolution was used (30,000 laser scan points and more): the titanium markers were detected with a mean deviation of 1.1 +/- 0.2 mm. Low resolution laser scans (6000 laser scan points of the surgical site and less) revealed inaccuracies up to 6 mm.

Humans↗

PubMed2004

Robots in the operating theatre--chances and challenges.

The use of surgical robots and manipulators is still being frequently discussed in the mass media as well as in the scientific community. Although it was already noted in 1985 that the first patient was treated by a joint team of robot and surgeon, today such systems are not routinely used. This can be explained by the high complexity of such systems and the often limited usability, but also, that it is difficult for surgeons to accept "automatic" machines. In this paper the possibilities and chances of robots and manipulators will be explained and it will be shown that robots will never work alone in the operating theatre as it is common in industry today. On the other hand, also limitations and challenges will be outlined. Therefore first a review on today's systems is given in different disciplines including oral- and cranio-maxillofacial surgery, then advantages and disadvantages are shown.

Equipment Design↗