The AE4 transporter mediates kidney acid-base sensing.

The kidney plays a key role in the correction of systemic acid-base imbalances. Central for this regulation are the intercalated cells in the distal nephron, which secrete acid or base into the urine. How these cells sense acid-base disturbances is a long-standing question. Intercalated cells exclusively express the Na+-dependent Cl-/HCO3- exchanger AE4 (Slc4a9). Here we show that AE4-deficient mice exhibit a major dysregulation of acid-base balance. By combining molecular, imaging, biochemical and integrative approaches, we demonstrate that AE4-deficient mice are unable to sense and appropriately correct metabolic alkalosis and acidosis. Mechanistically, a lack of adaptive base secretion via the Cl-/HCO3- exchanger pendrin (Slc26a4) is the key cellular cause of this derailment. Our findings identify AE4 as an essential part of the renal sensing mechanism for changes in acid-base status.

[Formation of desmoids in postoperative lumbar scars--a case report]. / Desmoidbildung in postoperativer lumbaler Narbe -- kasuistischer Beitrag.

Desmoids are tumours of the connective tissue cells with aggressive growth. Frequent recurrences of these tumours have often been described. Genetic and endocrine factors as well as local tissue biomechanics are thought to be responsible for the pathogenesis. This case report should contribute to the discussion about possible pathogenetic factors.

Neurobiology of polarization vision in the locust Schistocerca gregaria.

The polarization pattern of the blue sky serves as an important reference for spatial orientation in insects. To understand the neural mechanisms involved in sky compass orientation we have analyzed the polarization vision system in the locust Schistocerca gregaria. As in other insects, photoreceptors adapted for the detection of sky polarization are concentrated in a dorsal rim area (DRA) of the compound eye. Stationary flying locusts show polarotactic yaw-torque responses when illuminated through a rotating polarizer from above. This response is abolished after painting the DRAs. Central stages of the polarization vision system, revealed through tracing studies, include dorsal areas in the lamina and medulla, the anterior lobe of the lobula, the anterior optic tubercle, the lateral accessory lobe and the central complex. Physiological analysis of polarization-sensitive (POL) neurons has focussed on the optic tubercle and on the central complex. Each POL neuron was maximally excited at a certain e-vector (phimax) and was maximally inhibited at an e-vector perpendicular to phimax. The neurons had large visual fields, and many neurons received input from both eyes. The neuronal organization of the central complex suggests a role as a spatial compass within the locust brain.

Laser-induced thermotherapy of neoplastic lesions in the brain--underlying tissue alterations, MRI-monitoring and clinical applicability.

Laser-induced thermotherapy (LITT) is a minimally invasive neurosurgical approach to the stereotactic treatment of brain tumors in poorly accessible regions. Its clinical applicability has been shown in several experimental and clinical studies under on-line monitoring by magnetic resonance imaging (MRI). This review characterizes LITT as an alternative neurosurgical approach with specific focus on the typical histological alterations and ultrastructural cellular changes following laser irradiation in the central nervous system. The spatial and temporal pattern of these changes is discussed in their relevance to the neurosurgical treatment of neoplastic lesions using LITT.

Prognostic significance of SSEP, BAEP and serum S-100B monitoring after aneurysm surgery.

OBJECTIVE: Changes in evoked potentials (EPs) and increased levels of S-100B protein were used to identify cerebral ischemia or glial damage and to predict neurological outcome in aneurysm patients. MATERIAL AND METHODS: Somatosensory evoked potentials and Brainstem auditory-evoked potentials, and serum S-100B protein were simultaneously investigated pre- and postoperatively over a period of 10 days in 43 patients with 47 aneurysms (six in the posterior fossa). RESULTS: The EP scores showed a strong correlation with the clinical outcome. Sensitivity was 73%, and specificity 81%. Pathological S-100B levels >0.5 mg/l were equal in predictive values (correct positive eight, false positive six, correct negative 26, false negative three). Initially increased S-100B levels, long-lasting S-100B elevation, and secondary increasing S-100B values correlated with an unfavorable outcome. High peak S-100B values correlated with bad EP scores at discharge. EP deterioration was the first indicator anticipating S-100B elevation and clinical deterioration in five patients. There was a good correlation between pathological S-100B values or EP findings and infarction on CT scan. CONCLUSIONS: Both EPs and S-100B protein showed a comparable high predictive value for outcome. S-100B reflects the extent of primary brain damage after subarachnoid hemorrhage and time course of ongoing secondary brain damage. Evoked potentials assess the functional integrity and tended to react earlier than S-100B protein before definitive structural damage occurred.

Coagulopathy and outcome in patients with chronic subdural haematoma.

OBJECTIVE: The coincidence of coagulatopathy and chronic subdural haematoma (CSH) requires correction of coagulation to facilitate surgery. We investigated the correlation between coagulopathy and outcome in CSH patients. MATERIAL AND METHODS: We analysed past medical history, surgical treatment and coagulation parameters of 114 patients. RESULTS: Coagulation disorders were found in 42%. Preoperative treatment with prothrombin complex concentrate was necessary in 14%. A significant difference (P < 0.05) of the preoperative level of platelets was found between recurrent CSH and non-recurrent group. Totally, we had to perform re-operations in 17.5%. Eighty-one patients presented with Glasgow coma scale (GCS) > or = 13. After surgery GCS was > or = 13 in n = 92. There was an improvement of GCS in 46 cases, 61 patients maintained GCS score levels. Outcome was significantly worse in the alcoholic group (P < 0.001), and in the recurrent group (P < 0.05). In patients with substitution of coagulation factors, outcome was worse in the group with post-operative substitution only (P < 0.05). CONCLUSION: In CSH, the coagulation parameters and a subtle correction of coagulation are of special interest, regarding the worse outcome in patients with recurrent CSH and in those requiring post-operative substitution.

[Comparative studies of patient positioning for lumbar intervertebral disk operation]. / Vergleichende Untersuchungen zur Lagerung bei lumbalen Bandscheibenoperationen.

For surgery on lumbar disks by the posterior route, patients are placed either on a Wilson frame or in genupectoral position. The aim of the prospective study was to record and describe the haemodynamic changes resulting from the patients' position. After written informed consent had been received, 80 neurosurgical patients undergoing lumbar disk surgery were randomly divided into two groups; group I--Wilson frame, group II--genupectoral position. In each group, 20 patients received total intravenous anaesthesia (Alfentanil or Remifentanil, Propofol) and 20 balanced anaesthesia with Isoflurane and Alfentanil or Remifentanil. Haemodynamic parameters (mean arterial pressure--MAP and heart rate--HR) were recorded automatically at three measuring times (MT): firstly, after induction of anaesthesia; secondly, before re-direction; thirdly, after re-direction on the Wilson frame or in the genupectoral position. Induction of anaesthesia did not lead to a significant decrease in MAP (MT 1: 92.5 +/- 15.2 mmHg, MT 2: 89 +/- 13.4 mmHg, n = 80). In group I (n = 40), no significant changes were observed in MAP and HR at MT 3 (p = 0.882, p = 0.051). In comparison to group I, the genupectoral position was associated with significant drops in MAP and HR. The genupectoral position caused a significant decrease in MAP (p < 0.001) and HR (p = 0.016) at MT 3. Our data suggest that body weight or body mass index do not necessarily lead to a preference for one of the two possible positions of the patient. Complications resulting from haemodynamic changes were not seen in either group. We recommend the Wilson frame for neurosurgical lumbar disk surgery in cases of cardiovascular or cerebrovascular disorders. The adaptive capacities in the genupectoral position as a result of the modifying distribution of blood volume are limited in these patients. Furthermore, the dose-dependent effects of different anaesthetics on haemodynamic parameters in these prone positions should be explored.

Microendoscopic lumbar discectomy versus open surgery: an intraoperative EMG study.

This study investigated electromyographic (EMG) activity as a marker of nerve root irritation during two different surgical procedures for lumbar disc herniation. Mechanically elicited EMG activity was recorded during the dynamic stages of surgery in muscle groups innervated by lumbar nerve roots. Confirmation of surgical activity was correlated with the activity of the electromyogram. Fifteen patients with lumbar disc herniations were treated via an endoscopic medial approach, and 15 patients via the open microscopic surgical technique. Results indicated that the endoscopic technique was superior to the open surgical technique and produced less irritation of the nerve root. Significantly less mechanically elicited activity was recorded during both the approach and the root mobilization. The study showed that microendoscopic discectomy allows a smaller incision and less tissue trauma with comparable visualization of the nerve structures than does open surgery.

Functional MRI of the spine: different patterns of positions of the forward flexed lumbar spine in healthy subjects.

Since the introduction of the technique of vertical open-configuration systems, efforts have been made to obtain functional lumbar spinal magnetic resonance (MR) images. The purpose of this study was to determine the relation between facet joint orientation and flexion patterns in the lower lumbar spine. Thirty-four normal subjects (18 women, 16 men) were examined in a vertical open 0.5-T MR scanner with T1-weighted gradient echo (GE) sequences. Flexion angles were digitally measured in the sagittal plane and facet joint orientation in the axial plane. The population showed three different functional flexion patterns: 17.6% (n=6) had kyphotic angles in all three lower lumbar levels during forward flexion (type 1), 50% (n= 17) had a lordotic angle at L5/S1 but kyphotic angles at L4/L5 and L3/L4 (type 2), and 32.4% (n=11) showed lordotic angles at L5/S1 and L4/L5 but a kyphotic angle at L3/L4 (type 3). There were statistically significant differences between flexion patterns and mean facet joint orientation: at 4/15 33.3 degrees for type 1, 33.5 degrees for type 2 and 46.2 degrees for type 3; at L5/S1 27.2 degrees for type 1, 46.4 degrees for type 2 and 48.1 degrees for type 3. There were no significant differences between the three groups at L3/L4. The three different flexion patterns in normal subjects and their relation to facet joint orientation have not been described previously. Knowledge of these patterns may lead to a better understanding of physiological spinal movement as a base for future investigations in low back pain patients.

Dynamic examination of the lumbar spine by using vertical, open magnetic resonance imaging.

OBJECT: The aim of this study was to determine the relationship of different structures of the lower lumbar spine during interventional movement examination. METHODS: Clinically healthy volunteers and patients suffering from degenerative disorders of the lumbar spine underwent vertical, open magnetic resonance (MR) imaging (0.5 tesla). Three functional patterns of lumbar spine motion were identified in 50 healthy volunteers (average age 25 years). The authors identified characteristic angles of the facet joints, as measured in the frontal plane. In 50 patients with degenerative disorders of the lumbar spine (41 with disc herniation, five with osteogenic spinal stenosis, and four with degenerative spondylolisthesis) the range of rotation was increased in the relevant spinal segments. Signs of neural compression were increased under motion. CONCLUSIONS: Dynamic examination in which vertical, open MR imaging is used demonstrated that the extent of neural compression as well as the increasing range of rotation are important signs of segmental instability.

[Brain tumor resections in an open 0.5-T MRT. 2 years' experiences from the neuroradiological viewpoint]. / Hirntumorresektionen in einem offenen 0,5 T-MRT. Zweijährige Erfahrungen aus neuroradiologischer Sicht.

After two years clinical experience using an open 0.5 T-MRI, which make it possible to control all steps of a brain tumor resection, the high expense in relation to the effect is proofed. In 80 MRI-guided brain tumor resections the indication, the degree of resection, the appearance of operative induced changes, complications and clinical state are analysed. The advantage of the method consists in safety of localisation and detection especially of intra-axial cerebral tumors, recording of intraoperative invisible tumor parts and saving eloquent areas during tumor resection. To have optimal results, all over the operation time, the participation of a special experienced radiologist is necessary. The best results are shown in treatment of low grade gliomas and tumors near eloquent areas.

Spinal markers: A new method for increasing accuracy in spinal navigation.

Spinal navigation opens up a completely new dimension in the planning and realization of neurosurgical and orthopedic procedures, and offers the possibility of simulating the operation preoperatively. There is currently only limited experience with spinal navigation, and despite the development of advanced software, intraoperative difficulties include identification of characteristic and reproducible anatomical landmarks, localization of these points in the surgical field, referencing, and intraoperative control. We report the use of a new kind of implantable fiducial marker in a case of a 58-year-old female patient with spondylolisthesis. Percutaneously applied spinal markers were used as prominent anatomical landmarks and permitted much easier intraoperative handling. In our opinion, in the hands of an experienced neurosurgeon or orthopedist, the additional preoperative time required for placement of such spinal markers is negligible.

Open MRI-guided neurosurgery.

OBJECTIVES: A number of different image-guided surgical techniques have been developed during the past decade. None of these methods can provide the surgeon with information about the dynamic changes that occur intra-operatively. MATERIAL AND METHOD: The first vertical open 0.5T MRI-scanner for intra-operative MRI-guided neurosurgery in Germany was installed at the University of Leipzig during the summer 1996. Since autumn 1996 a number of surgical procedures including biopsies (n = 31), craniotomies (n = 32), transsphenoidal procedures (n = 8) and interstitial lasertherapies (n = 3) have been performed using intra-operative MR image guidance. RESULTS: The development of MR-compatible and MR-safe non-magnetic instruments and components had to be solved. Specific surgical instruments were developed to perform biopsies, craniotomies, microsurgical tumour resections and transsphenoidal procedures in the 0.5-T open MRI. Several components required adaptation including the head holder the stereotactic navigation device, the high speed drill, the suction unit, the ultrasonic aspirator, the bipolar coagulation, the laser probe and the surgical microscope. All these newly developed technical features enable the neurosurgeon to perform a large number of surgical procedures under direct control and guidance of intra-operative MR imaging. In contrast to frame-based for framless navigation systems, intra-operative MRI provides accurate and immediate information during the progress of surgery. These intra-operative images allow definitive localization and targeting of the lesions and accommodate anatomical changes that may occur during surgery. CONCLUSION: Intra-operative MRI is helpful for navigation as well as determining of tumour margins to achieve a complete and safe resection of intracranial lesions. Complications related to the surgical procedure are reduced and the risk of neurological deterioration due to tumour removal and postoperative complications is minimized. It can be concluded that the intra-operative application of interventional MRI technology may represent a major step forward in the field of neurosurgery.

Immunocytochemistry of GABA in the central complex of the locust Schistocerca gregaria: identification of immunoreactive neurons and colocalization with neuropeptides.

The central complex is a highly organized neuropil structure in the insect brain and plays a role in motor control and visual orientation. We describe the distribution of gamma-aminobutyric acid (GABA) immunostaining in the central complex of the locust Schistocerca gregaria in an effort to analyze inhibitory neural circuits within this brain area. Antisera against GABA and the GABA-synthesizing enzyme glutamic acid decarboxylase resulted in identical patterns of immunostaining. Cell counts revealed about 100 bilateral pairs of GABA-immunoreactive neurons with arborizations in the central complex. Five types of immunostained neurons could be identified through reconstruction of the staining pattern, comparison with individually stained neurons, and double labeling experiments with Neurobiotin-injected neurons. All of these GABA-immunostained neurons are tangential neurons that connect the lateral accessory lobes to distinct layers of the central body. Three types of immunostained neurons (TL2, TL3, TL4) invade the lower division of the central body, and two additional types of neurons (TU1, TU2) have ramifications in layers I and II of the upper division of the central body. Double-labeling experiments with peptide antisera suggest that peptides related to Phe-Met-Arg-Phe-NH2/bovine pancreatic polypeptide and Dip-allatostatin might act as cotransmitters with GABA in TL4 neurons of the lower division and (Dip-allatostatin only) in TU2 neurons of the upper division of the central body. The high conservation in the pattern of GABA immunostaining in all insect species investigated so far suggests that GABA plays an essential role in the basic neural circuitry of the central complex in insects.

Immunocytochemical demonstration of locustatachykinin-related peptides in the central complex of the locust brain.

The central complex, a highly ordered neuropil area in the insect brain, plays a role in motor control and spatial orientation. To further elucidate the neurochemical architecture of this brain area, we have investigated the distribution and morphology of neurons containing locustatachykinin I/II-related substances in the central complex of the locust Schistocerca gregaria. The central complex is innervated by at least 66 locustatachykinin I/II-immunoreactive neurons, which belong to two sets of tangential neurons and four sets of columnar neurons. These neurons give rise to immunostaining in the protocerebral bridge, in several layers of the upper division of the central body, and in all layers except layer 5 of the lower division of the central body. Double-label experiments show colocalization of immunoreactivity for both locustatachykinin I/II and octopamine in tangential neurons of the protocerebral bridge. A pair of tangential neurons of the lower division of the central body exhibits both locustatachykinin I/II and gamma-aminobutyric acid (GABA) immunoreactivity. A set of 16 columnar neurons of the lower division of the central body shows colocalized immunoreactivity for locustatachykinin II, leucokinin, and substance P. This study reveals novel features of the anatomical organization of the locust central complex and suggests a prominent role for locustatachykinin-related peptides as neuromediators and cotransmitters within this brain area.

[Correlation between ear canal resonance and tympanic membrane impedance in relation to age and body mass and postmortem changes]. / Untersuchung über Korrelation von Gehörgangsresonanz und Trommelfellimpedanz bezüglich Alter und Körpermassen sowie Veränderungen nach Todeseintritt.

The human temporal bone preparation is an acknowledged model for research of the physical processes affecting the outer ear canal and eardrum. Changes affecting the oscillation and resonance behavior of the tympanic membrane and ear canal between death and temporal bone preparation presently exist in only a few studies. Since the influence of age and physique, as well as the width of ear canal on the ear canal resonance may be important, we prepared two separate studies to analyze these questions. The goal of our first test series involved children and was devised to determine if changes in the outer auditory canal resonances differed according to age. In so doing, canal resonance was recorded with a real ear measurement system. Further, we recorded middle ear pressure, impedance of the tympanic membrane, ear canal volume, height, weight and surface of the body, head and ear size. We found a significant decrease in the resonance frequency of the outer ear which was age-dependent and was 2.75 kHz in the 7-year-old child. In a separate study we wanted to know if results found in the postmortem temporal bone reflected in vivo relationships. A tympanometer and real ear measurement system was used to test the resonance behavior of the auditory canal as well as the vibration of the eardrum in dependence on temperature and the time after death for 9 h. We then proved the absence of significant changes in the auditory canal and eardrum oscillation in this time period before possible postmortem changes occurred. Our findings show that the method of bone preservation after its preparation is decisive for the validity of measurements in the isolated human temporal bone.

Distribution of Dip-allatostatin I-like immunoreactivity in the brain of the locust Schistocerca gregaria with detailed analysis of immunostaining in the central complex.

The distribution and morphology of neurons containing allatostatin-related substances in the brain of the locust Schistocerca gregaria was investigated using an antiserum against Diploptera punctata allatostatin I (Dip-allatostatin I, APSGAQRLYGFGL-amide). In each brain hemisphere, about 550 neurons in the midbrain and 500 neurons in the optic lobe exhibit Dip-allatostatin I-like immunoreactivity, including about eight lateral neurosecretory cells with processes to the retrocerebral complex. All major brain areas except the antennal lobe, the mushroom body, and large parts of the lamina, are innervated by Dip-allatostatin I-immunoreactive processes. Immunostaining in the central complex was studied in detail. The central complex is innervated by more than 260 Dip-allatostatin I-immunoreactive neurons belonging to six different cell types, four sets of tangential neurons and two sets of columnar neurons. These neurons give rise to intense immunostaining in the protocerebral bridge, in several layers of the upper division of the central body, and in the dorsalmost layer of the lower division of the central body. Double-label experiments show colocalization of Dip-allatostatin I- and serotonin-like immunoreactivities in one type of columnar and one type of tangential neurons of the central complex. The similar patterns of Dip-allatostatin I- and galanin message-associated peptide-like immunoreactivities result from cross-reactivity of the anti-galanin message-associated peptide antiserum with Dip-allatostatin I. The results provide further insight into the anatomical and neurochemical organization of the locust central complex and suggest a prominent neuroactive role for Dip-allatostatin I-related peptides in this brain area.

[Postmortem changes in ear canal resonance and tympanic membrane impedance in the human ear]. / Zur Untersuchung postmortaler Veränderungen von Gehörgangsresonanz und Trommelfellimpedanz am menschlichen Ohr.

BACKGROUND: The human temporal bone preparation is a common model for research of physical processes of the ear canal and middle ear. In the past decade only a few reports were published discussing changes of the vibration behaviour of the tympanic membrane, as well as the ear canal resonance, during the time between death and preparation of the temporal bone. The aim of our study is to verify whether measurements at the temporal bone of dead humans can be really applied to the in vivo situation. METHODS: We investigated whether changes of the ear canal resonance and the vibration of the tympanic membrane depend on temperature and time after death. In a female human body we defined the resonance of the outer ear and the impedance of the tympanic membrane using a tympanometer and a real ear measurement system during nine hours post mortem. RESULTS: We were able to prove that before the preparation of the temporal bone none of the parameters changed significantly. CONCLUSIONS: In conclusion, the method of preserving the bone after its preparation is decisive for the validity of measurements at the isolated (post mortem) human temporal bone.

[Severe pulmonary complications following venous air embolism in neurosurgical operations in sitting position--2 case reports]. / Schwere pulmonale Störungen nach venöser Luftembolie bei neurochirurgischen Operationen in sitzender Position--zwei Fallberichte.

The occurrence of air embolism during neurosurgical operations in sitting position is described in two cases. Besides the Doppler ultrasound evidence, relevant effects on the cardiopulmonary situation during surgery were observed, which in one case forced an early end of the operation. Postoperative management in both cases was complicated by a pulmonary oedema. In severe intraoperative cardiopulmonary complications in connection with venous air embolism, the existence of pulmonary oedema should be assumed. Confirmation of the diagnosis and the correct therapy depend upon frequent postoperative chest X-rays.

[A new set for percutaneous implantation of the cardiac catheter in ventriculo-atrial shunt systems. A new technical note]. / Ein neues Set zur perkutanen Plazierung des kardialen Katheters ventrikuloatrialer Shuntsysteme. Eine technische Notiz.

The percutaneous insertion of the atrial catheter for ventriculoatrial shunts reveals as a sufficient alternative method for the open surgical preparation of neck veins. The authors use a special set based on the Seldinger-Technique. The direct punction procedure of the internal jugular vein is a wellknown method in anaesthesia and intensive-care-medicine. First experiences show as well as a shorter operation times and better cosmetic results in the neck region.