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
/HCO
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
/HCO
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.
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.
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) ≥ 13. After surgery GCS was ≥ 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.
Open MRI-guided neurosurgery Seifert, V; Zimmermann, M; Trantakis, C ...
Acta neurochirurgica,
01/1999, Letnik:
141, Številka:
5
Journal Article
Recenzirano
Odprti dostop
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.
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.
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.
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.
The aim of this study was to determine the relationship of different structures of the lower lumbar spine during interventional movement examination.
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.
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.
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.
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.
Claudins are major components of tight junctions and contribute to the epithelial-barrier function by restricting free diffusion of solutes through the paracellular pathway. We have mapped a new ...locus for recessive renal magnesium loss on chromosome 1p34.2 and have identified mutations in
CLDN19, a member of the claudin multigene family, in patients affected by hypomagnesemia, renal failure, and severe ocular abnormalities.
CLDN19 encodes the tight-junction protein claudin-19, and we demonstrate high expression of
CLDN19 in renal tubules and the retina. The identified mutations interfere severely with either cell-membrane trafficking or the assembly of the claudin-19 protein. The identification of
CLDN19 mutations in patients with chronic renal failure and severe visual impairment supports the fundamental role of claudin-19 for normal renal tubular function and undisturbed organization and development of the retina.
Impaired magnesium reabsorption in patients with TRPM6 gene mutations stresses an important role of TRPM6 (melastatin-related TRP cation channel) in epithelial magnesium transport. While attempting ...to isolate full-length TRPM6, we found that the human TRPM6 gene encodes multiple mRNA isoforms. Full-length TRPM6 variants failed to form functional channel complexes because they were retained intracellularly on heterologous expression in HEK 293 cells and Xenopus oocytes. However, TRPM6 specifically interacted with its closest homolog, the Mg2+-permeable cation channel TRPM7, resulting in the assembly of functional TRPM6/TRPM7 complexes at the cell surface. The naturally occurring S141L TRPM6 missense mutation abrogated the oligomeric assembly of TRPM6, thus providing a cell biological explanation for the human disease. Together, our data suggest an important contribution of TRPM6/TRPM7 heterooligomerization for the biological role of TRPM6 in epithelial magnesium absorption.
Magnesium is an essential ion involved in many biochemical and physiological processes. Homeostasis of magnesium levels is tightly regulated and depends on the balance between intestinal absorption ...and renal excretion. However, little is known about specific proteins mediating transepithelial magnesium transport. Using a positional candidate gene approach, we identified mutations in TRPM6 (also known as CHAK2), encoding TRPM6, in autosomal-recessive hypomagnesemia with secondary hypocalcemia (HSH, OMIM 602014), previously mapped to chromosome 9q22 (ref. 3). The TRPM6 protein is a new member of the long transient receptor potential channel (TRPM) family and is highly similar to TRPM7 (also known as TRP-PLIK), a bifunctional protein that combines calcium- and magnesium-permeable cation channel properties with protein kinase activity. TRPM6 is expressed in intestinal epithelia and kidney tubules. These findings indicate that TRPM6 is crucial for magnesium homeostasis and implicate a TRPM family member in human disease.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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