Ancient Oil as a Source of Carbonaceous Matter in 1.88-Billion-Year-Old Gunflint Stromatolites and Microfossils.

The 1.88-billion-year-old Gunflint carbonaceous microfossils are renowned for their exceptional morphological and chemical preservation, attributed to early and rapid entombment in amorphous silica. The carbonaceous matter lining and partly filling filamentous and spherical structures is interpreted to be indigenous, representing thermally altered relicts of cellular material (i.e., kerogen). Here we show that stromatolitic black cherts from the Gunflint Formation, Schreiber Beach, Ontario, Canada, were saturated in syn-sedimentary oil. The thermally altered oil (pyrobitumen), which occurs in the stromatolites and intercolumn sediments, fills pores and fractures, and coats detrital and diagenetic grain surfaces. The occurrence of detrital bitumen grains in the stromatolites points to the proximity of shallow seafloor oil seeps and hence the possible existence of chemosynthetic microbes degrading hydrocarbons. We suggest that hydrocarbons that migrated through the silicifying stromatolites infiltrated semi-hollow microbial molds that formed following silica nucleation on the walls or sheaths of decayed cells. Upon heating, the hydrocarbons were transformed to nanoporous pyrobitumen, retarding silica recrystallization and enhancing detailed preservation of the carbon-rich microfossils. Hydrocarbon infiltration of silicified microbes offers a new explanation for the preservation of the Gunflint microfossils and may have played a role in the formation of some of Earth's oldest microfossils.

Controlled mechanical ventilation to detect regional lymph node metastases in esophageal cancer using USPIO-enhanced MRI; comparison of image quality.

BACKGROUND: Artifacts caused by respiratory motion or ventilation-induced chest movements are a major problem for thoracic MRI, as they can obscure important anatomical structures such as lymph node metastases. We compared image quality of routine breathhold with intermittent apnea during controlled mechanical ventilation of patients under general anesthesia as the ideal situation without respiratory motion in the detection and characterization of regional lymph nodes in esophageal cancer. METHODS: In this prospective study, 10 patients treated for esophageal cancer underwent ultrasmall superparamagnetic iron oxide (USPIO) enhanced MRI scans. Before neoadjuvant therapy, MRI scans were acquired with a routine breathhold technique. After neoadjuvant therapy, patients were scanned under general anesthesia immediately prior to surgery with controlled mechanical ventilation. The image quality was compared using a Likert scale questionnaire based on visibility of anatomical structures and image artifacts. RESULTS: MRI with controlled mechanical ventilation and prolonged controlled apnea of 4 min was safe and feasible. All cardio-respiratory monitoring parameters remained stable during the apnea phases. Mediastinal and upper abdominal lymph nodes down to 2 mm in size could be visualized with all sequences. All image quality criteria, including visibility of thoracic structures and regional lymph nodes were scored higher using the controlled ventilation sequences compared to the routine breathhold phase. CONCLUSION: USPIO-enhanced MRI with controlled mechanical ventilation is superior to routine breathhold MRI in visualizing lymph nodes, which warrants new motion reduction techniques to use MRI for the detection of lymph node metastases in patients with esophageal cancer.

Long-term incidence of sensory disturbance in the forehead after fronto-orbital advancement in isolated nonsyndromic craniosynostosis.

In the majority of the craniofacial literature, preservation of the supraorbital nerve during fronto-orbital advancement (FOA) is recommended. However, only a few studies have evaluated the incidence of sensory disturbance in the forehead after FOA during long-term follow-up. 57 children who underwent FOA in their first year of life because of isolated nonsyndromic craniosynostosis including trigonocephaly, anterior plagiocephaly or oxycephaly, were evaluated for sensory disturbance in the frontal region with a minimum follow-up of 27 months. An objective and repeatable measurement using the Semmes-Weinstein test was possible in 36 children older than 5 years at last follow-up. We revealed no sensory deficits in all patients, even in 3 patients, where one of the supraorbital nerves was transected during FOA. As previous reports have suggested a full recovery of sensation after transection of the supraorbital nerve during FOA I seen, the need to preserve the nerve has to be evaluated. However, as release of the nerve from the supraorbital rim is possible, we generally recommend preserving this structure, to minimize the risk of sensory deficits in the forehead region.

Long-term results in nonsyndromatic unilateral coronal synostosis treated with fronto-orbital advancement.

Children with unilateral isolated coronal suture synostosis suffer from frontal plagiocephaly. In this retrospective study we analyzed 21 patients who were treated with an identical and standardized surgical technique of fronto-orbital advancement with hypercorrection with an average follow-up of 57.5 months. The median age at surgery was 12.1 months. The median average amount of blood loss during the operation was less than 188 ml. Not a single major complication was observed. According to the classification of Whitaker, 15 patients had a Class 1 outcome, with excellent surgical results. Three patients were defined as Class 2 outcome. One of our patients was Class 3 and two patients were Class 4 because of severe forehead retrusion and temporal hollowing. Re-operation rate was 14.3%. 67% of our patients showed a correction or an improvement of the typical C-shaped deformity in their follow-up examination. Aesthetic outcomes were excellent in 13, good in 5, and poor in 3 of cases, as judged by their families and the craniofacial team. Unilateral coronal synostosis can be successfully treated by fronto-orbital advancement with a low complication rate and an excellent clinical outcome. To minimize the need of re-operations, fronto-orbital advancement should be performed with an overcorrection on the affected side.

Subtotal cranial vault remodelling in anterior sagittal suture closure: impact of age on surgical outcome.

Isolated fusion of the sagittal suture is usually treated before 1 year of age, but some patients present at a later age. The aim of this study was to evaluate the impact of children's age on the surgical outcome. The authors investigated 46 patients with isolated nonsyndromic sagittal craniosynostosis limited to the anterior two-thirds of the cranial vault. All patients underwent subtotal cranial vault remodelling, 36 patients (78.3%) before the age of 12 months (mean 8.92 months) and 10 patients after the age of 12 months (mean 15.77 months). Perioperative parameters and measurements of the cephalic index, preoperatively and postoperatively, were evaluated. All 46 patients showed improved head shape independent of their age. In patients younger than 12 months, mean cephalic indices improved from 65.99 to 74.49 (p<0.0001) and in patients older than 12 months from 66.38 to 74.38 (p<0.0004). There were no statistical differences in perioperative parameters including length of surgery, intraoperative blood loss and duration of hospital stay. In this study, patients showed no significant differences in surgical outcome that could have been related to the age at surgery. Surgical treatment should be performed early enough to benefit from the remodelling potential of the skull.

Surgical outcome after using a modified technique of the pi-procedure for posterior sagittal suture closure.

Fusion of the sagittal suture is the most prevalent form of craniosynostosis. Due to the variety of deformities of scaphocephaly depending on the location of the fused sagittal suture, the surgical procedure has to be adjusted to the individual case. In this study, 38 patients with a predominantly posterior sagittal suture closure were treated with a modified technique of the pi-procedure and the surgical outcome has been evaluated with respect to complications, morphological and aesthetic outcome. The improvement of the cephalic index in our series in the follow-up examination (mean 60.1 months) after surgery was significant (p<0.0001). According to the classification of Whitaker, 31 patients had a Class 1 outcome, with excellent surgical results. Aesthetic outcomes were excellent in 29, good in 5, and poor in 4 of cases, as judged by both the families and the craniofacial team. No severe complications have been observed. Posterior sagittal suture with marked occipital bulging can be successfully treated with this modified posterior procedure with a low complication rate, significant improvement of the cephalic index and a good aesthetic outcome. In all cases of sagittal synostosis, the operative procedure should be tailored to the nature and severity of the deformity.

Negative impact of rAAV2 mediated expression of SOCS3 on the regeneration of adult retinal ganglion cell axons.

Intravitreal injections of recombinant ciliary neurotrophic factor (rCNTF) protect adult rat retinal ganglion cells (RGCs) after injury and stimulate regeneration, an effect enhanced by co-injection with a cAMP analogue (CPT-cAMP). This effect is partly mediated by PKA and associated signaling pathways, but CPT-cAMP also moderates upregulation of suppressor of cytokine signaling (SOCS) pathways after rCNTF injection, which will also enhance the responsiveness of RGCs to this and perhaps other cytokines. We now report that intravitreal injections of CPT-cAMP do not potentiate RGC axonal regeneration when CNTF is expressed via an adeno-associated viral vector (rAAV2), and concomitantly we show that increases in retinal SOCS mRNA expression are less when CNTF is delivered using the vector. We also directly tested the impact of elevated SOCS3 expression on the survival and regeneration of injured adult RGCs by injecting a bicistronic rAAV2-SOCS3-GFP vector into the vitreous of eyes in rats with a peripheral nerve graft sutured onto the cut optic nerve. Overexpression of SOCS3 resulted in an overall reduction in axonal regrowth and almost complete regeneration failure of RGCs transduced with the rAAV2-SOCS3-GFP vector. Furthermore, rAAV2-mediated expression of SOCS3 abolished the normally neurotrophic effects elicited by intravitreal rCNTF injections. In summary, CNTF delivery to the retina using viral vectors may be more effective than bolus rCNTF injections because the gene therapy approach has a less pronounced effect on neuron-intrinsic SOCS repressor pathways. Our new gain of function data using rAAV2-SOCS3-GFP demonstrate the negative impact of enhanced SOCS3 expression on the regenerative potential of mature CNS neurons.

Computer-assisted three-dimensional surgical planning: 3D virtual articulator: technical note.

This study presents a computer-assisted planning system for dysgnathia treatment. It describes the process of information gathering using a virtual articulator and how the splints are constructed for orthognathic surgery. The deviation of the virtually planned splints is shown in six cases on the basis of conventionally planned cases. In all cases the plaster models were prepared and scanned using a 3D laser scanner. Successive lateral and posterior-anterior cephalometric images were used for reconstruction before surgery. By identifying specific points on the X-rays and marking them on the virtual models, it was possible to enhance the 2D images to create a realistic 3D environment and to perform virtual repositioning of the jaw. A hexapod was used to transfer the virtual planning to the real splints. Preliminary results showed that conventional repositioning could be replicated using the virtual articulator.

Glutamine administration in patients undergoing cardiac surgery and the influence on blood glutathione levels.

BACKGROUND: Cardiac surgery with an extracorporeal circulation cardiopulmonary bypass (CPB) is characterized by an oxidative stress response. Glutathione (GSH) belongs to the major antioxidative defense. In metabolic stress, glutamine (GLN) may be the rate-limiting factor of GSH synthesis. Decreased GLN plasma levels were observed after various critical states. We evaluated, in patients undergoing open heart surgery with CPB, the effects of a peri-operative GLN supplementation on GSH in whole blood and assessed their influence on the Sequential Organ Failure Assessment score and the intensive care unit length of stay. METHODS: In this prospective, randomized, double-blinded study, we included 60 patients (age older than 70 years, ejection fraction <40% or mitral valve replacement) undergoing an elective cardiac surgery with CPB. We randomly assigned each subject to receive an infusion with either GLN (0.5 g/kg/day, group 1) or an isonitrogeneous, isocaloric, isovolemic amino acids solution (group 2) or saline (group 3). RESULTS: From the first post-operative day GLN plasma levels in group 1 were significantly increased compared with the other groups. With saline GSH the levels decreased significantly post-operatively compared with GLN. We observed a significant correlation between GLN delivery and GSH levels. CONCLUSIONS: A peri-operative high-dose GLN infusion increased plasma GLN concentrations and maintained the GSH levels after cardiac surgery with CPB.

Perioperative application of L-alanyl-L-glutamine in cardiac surgery: effect on the polarized T cell cytokine expression.

At risk patients undergoing cardiac surgery with cardiopulmonary bypass have increased rates of postoperative infectious morbidity. Postoperatively, after cardiac surgery, an immunosuppression in the form of a polarization of T helper (Th) cells with a decreased Th1 response (IL-2 and IFN-gamma) and an increased Th2 response (IL-4 and IL-10) is recognized. Therapeutic strategies to modulate the immunological response include special key nutrients such as the amino acid glutamine favoring the Th2 response. There is no information available concerning its effect in patients undergoing cardiac surgery. The aim of this clinical study was to evaluate the effects of a perioperative infusion of glutamine on the polarized lymphocyte T cell cytokine expression and on infectious morbidity in cardiac surgery patients at risk of infection. Seventy-eight patients were included in the study undergoing elective cardiac surgery with a lymphopenia less than 1.2 giga/l. One or more of the following criteria had to be met: age older than 70 years, ejection fraction less than 40%, or mitral valve replacement. We randomly assigned patients to receive infusions of either high-dose L-alanyl-L-glutamine dipeptide [0.5 g/(kg day) glutamine] dissolved in an amino acid solution or an isonitrogeneous, isocaloric, isovolemic nutritional solution. An additional group with normal saline served as control to eliminate any nonspecific nutritional effect. We started the infusion after induction of anesthesia with 1,000 ml/24 h and continued it for 3 days. The primary endpoint was intracellular T cell cytokine expression (including the description in tertiles) on the first postoperative day (pod 1). Secondary endpoints were postoperative infection rate, mortality rate, cardiovascular circulation ventilation time, and renal function. A high-dose perioperative glutamine application leading to mean plasma levels of 1,177 microM had only a minor influence on the polarized intracellular T cell cytokine expression. On pod 1 there was a polarization of T cells, i.e., an augmented Th2 response with an increased number of IL-6 and IL-10 producing cells. On the other side the Th1 response with IL-2 and TNF-alpha declined on pods 1 and 2. Only the intracellular IL-2 response in the lower tertile of IL-2 production was improved with glutamine indicating a small influence. We did not observe any effects on the numbers of postoperative infections; on mortality rate; on cardiovascular circulation; on ventilation time or on renal function. The elevation of glutamine plasma levels by a perioperative intravenous infusion of L-alanyl-L-glutamine influenced the intracellular expression of IL-2 in the lower tertile only slightly. However, mean glutamine values in the other groups remained above or close 500 microM, thus suggesting that glutamine supply to the immune cells was still adequate in most patients, and that glutamine deficiency, if it occurred, was marginal. In the event of a severe glutamine deficiency the observed effect on cytokine production could be more pronounced. Furthermore, we could not observe any obvious clinical advantage in this at risk cardiac surgical patient population. A glutamine supplementation for patients undergoing cardiac surgery without a clear glutamine deficiency is not recommended.

Intraoperative computed tomography and automated registration for image-guided cranial surgery.

OBJECTIVES: Two key problems for the use of navigation systems in image-guided surgery are accurate patient-to-image registration and the fact that with ongoing surgery the patient's anatomy is altered while the image data remains unchanged. A system for intraoperative CT imaging and fully automated registration of this image addresses both problems. It had been evaluated successfully in phantom studies. In this clinical study, we assessed the impact of the system on intraoperative workflow and registration accuracy in everyday patient care. METHODS: In ten patients who underwent image-guided surgery, CT image data were acquired intraoperatively and were automatically registered in the navigation system. Registration accuracy and surgical outcome were assessed clinically. In six of these patients, a maxillary splint with markers had been inserted to cross-check registration accuracy. The target registration error of these markers was measured. RESULTS: In all cases, registration accuracy was clinically sufficient and the surgical task could be performed successfully. In those cases where a maxillary template with target markers was attached for additional control of the registration accuracy, the target registration error was always better than 2 mm. Automated registration reduced the intraoperative registration time considerably and partially compensated for the time needed to perform the image data acquisition. CONCLUSIONS: Intraoperative CT imaging and automated registration successfully address the two key problems of image-guided surgery. The method is robust and accurate and proved its usability in everyday patient care.

Role of glutamine administration on T-cell derived inflammatory response after cardiopulmonary bypass.

BACKGROUND & AIMS: Cardiac surgery provokes an inflammatory response for which the endothelium, the myocardium, and monocytes/macrophages are primarily responsible. T cells are altered in a different way whereby the pro-inflammatory pathway is suppressed. From the results of experimental studies it was concluded that glutamine (Gln) enhances the production of T-cell cytokines in conditions of Gln deprivation. The aim of this clinical study was to evaluate the role of a perioperative Gln infusion on intracellular inflammatory T-cell cytokine expression in patients undergoing elective cardiac surgery and to evaluate the effects on systemic inflammation, organ dysfunction and ICU length of stay. METHODS: In this prospective, randomized, double-blind study, we included 78 patients (age level older than 70 years, ejection fraction less than 40%, or mitral valve replacement) undergoing elective cardiosurgery with cardiopulmonary bypass. We randomly assigned each subject to receive an infusion with either Gln (0.5 g/kg/day, group A) or an isonitrogenous, isocaloric, isovolemic nutritional solution (group B) or physiological NaCl 0.9% (group C, to eliminate an unspecific nutritional effect). We started the infusion after the induction of anesthesia with 1000 ml/24 h and maintained this state for 3 days. RESULTS: On the first postoperative day plasma Gln levels in group A were significantly increased (958 +/- 331 microM) compared to group B (527 +/- 105 microM) and group C (489 +/- 104 microM), and remained higher until the third postoperative day. At the beginning and after surgery intracellular interleukin (IL)-1, IL-6, IL-8, and tumor necrosis factor-alpha levels in T cells showed no differences between the groups. Also, no differences could be observed with regard to C-reactive protein, SOFA score, heart and circulation support, postoperative ventilation time, and ICU length of stay. CONCLUSIONS: The elevation of Gln plasma levels as a result of 0.5 g/kg/day perioperative Gln infusion has no influence on the T-cell derived inflammatory response, indicating a sufficient supply of Gln. A Gln supplementation in cardiac surgery patients without a clear Gln deficiency seems not to affect the intracellular inflammatory T-cell cytokine expression.

Geometric accuracy of digital volume tomography and conventional computed tomography.

Digital volume tomography is a recently established imaging method that is based on the principle of cone beam computed tomography (CBCT). One of its main applications is imaging in dental and maxillofacial surgery. The objective of this study was to compare the geometric accuracy of digital volume tomographic imaging with that of conventional CT and to assess the suitability for image-guided operating. A calibration cube with a defined pattern of tubes inside was scanned using CT and digital volume tomography. Spatial accuracy was analysed with a software evaluation tool. The positions of the intersections of the tubes were detected in imaging data and registered to the real positions in the calibration body. The deviation was calculated and compared for CT and digital volume tomography. Resolution of spatial images was similar for both methods. However, the spatial accuracy in digital volume tomography was slightly lower than that of CT but still in the submillimetric range. The accuracy was better in the middle, but lower in the margins of the volume. This is a disadvantage in technical image quality, but does not affect the diagnostic image quality. The geometric accuracy is sufficient for digital volume tomography-based image-guided surgery.

Automated registration of intraoperative CT image data for navigated skull base surgery.

OBJECTIVES: With a new intraoperative computed tomography (CT) imaging system, patient-to-image registration without any invasive registration markers is possible. Furthermore, registration can be performed fully automatically. The accuracy of this method for skull base surgery was investigated in this study. METHODS: We employed a phantom study design. A phantom skull was equipped with 33 target markers in the regions of the anterior and lateral skull base. CT image data were acquired with an intraoperative CT suite. Image data were transferred as DICOM data to the navigation system, and registration was performed automatically. For registration, the position of the patient and the position of the CT gantry were monitored in the imaging process, using the infrared camera of a navigation system. Using the pointing device of the navigation system, the target markers were identified. The accuracy was measured as the spatial difference of the target markers in image space and on the phantom. RESULTS: Accuracy was always sufficient for image-guided surgery of any region of the skull base, with an average target registration error of below 1.2 mm. In contrast to traditional non-invasive registration methods, there was no difference in registration accuracy between the anterior skull base and the lateral skull base. CONCLUSIONS: Fully automated registration based on a tracked CT gantry is a robust and accurate registration method for skull base surgery.

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.

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.

[Malposition of the orbita from the surgical point of view]. / Fehlstellung der Orbita aus chirurgischer Sicht.

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.

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.

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.

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.