Frustration can Limit the Adaptation of Promiscuous Enzymes Through Gene Duplication and Specialisation.

Virtually all enzymes catalyse more than one reaction, a phenomenon known as enzyme promiscuity. It is unclear whether promiscuous enzymes are more often generalists that catalyse multiple reactions at similar rates or specialists that catalyse one reaction much more efficiently than other reactions. In addition, the factors that shape whether an enzyme evolves to be a generalist or a specialist are poorly understood. To address these questions, we follow a three-pronged approach. First, we examine the distribution of promiscuity in empirical enzymes reported in the BRENDA database. We find that the promiscuity distribution of empirical enzymes is bimodal. In other words, a large fraction of promiscuous enzymes are either generalists or specialists, with few intermediates. Second, we demonstrate that enzyme biophysics is not sufficient to explain this bimodal distribution. Third, we devise a constraint-based model of promiscuous enzymes undergoing duplication and facing selection pressures favouring subfunctionalization. The model posits the existence of constraints between the catalytic efficiencies of an enzyme for different reactions and is inspired by empirical case studies. The promiscuity distribution predicted by our constraint-based model is consistent with the empirical bimodal distribution. Our results suggest that subfunctionalization is possible and beneficial only in certain enzymes. Furthermore, the model predicts that conflicting constraints and selection pressures can cause promiscuous enzymes to enter a 'frustrated' state, in which competing interactions limit the specialisation of enzymes. We find that frustration can be both a driver and an inhibitor of enzyme evolution by duplication and subfunctionalization. In addition, our model predicts that frustration becomes more likely as enzymes catalyse more reactions, implying that natural selection may prefer catalytically simple enzymes. In sum, our results suggest that frustration may play an important role in enzyme evolution.

Minimally invasive third ventriculostomy with stereotactic internal shunt placement for the treatment of tumor-associated noncommunicating hydrocephalus.

BACKGROUND: Intracranial tumors can cause obstructive hydrocephalus (OH). Most often, symptomatic treatment is pursued through ventriculoperitoneal shunt (VS) or endoscopic third ventriculostomy (ETV). In this study, we propose stereotactic third ventriculostomy with internal shunt placement (sTVIP) as an alternative treatment option and assess its safety and efficacy. METHODS: In this single-center, retrospective analysis, clinical symptoms, procedure-related complications, and revision-free survival of all patients with OH due to tumor formations treated by sTVIP between January 2010 and December 2021 were evaluated. RESULTS: Clinical records of thirty-eight patients (11 female, 27 male) with a mean age of 40 years (range 5-88) were analyzed. OH was predominantly (in 92% of patients) caused by primary brain tumors (with exception of 3 cases with metastases). Following sTVIP, 74.2% of patients experienced symptomatic improvement. Preoperative headache was a significant predictor of postoperative symptomatic improvement (OR 26.25; 95% CI 4.1-521.1; p = 0.0036). Asymptomatic hemorrhage was detected along the stereotactic trajectory in 2 cases (5.3%). One patient required local revision due to CSF fistula (2.6%); another patient had to undergo secondary surgery to connect the catheter to a valve/abdominal catheter due to CSF malabsorption. However, in the remaining 37 patients, shunt independence was maintained during a median follow-up period of 12 months (IQR 3-32 months). No surgery-related mortality was observed. CONCLUSIONS: sTVIP led to a significant symptom control and was associated with low operative morbidity, along with a high rate of ventriculoperitoneal shunt independency during the follow-up period. Therefore, sTVIP constitutes a highly effective and minimally invasive treatment option for tumor-associated obstructive hydrocephalus, even in cases with a narrow prepontine interval.

Nuclear translocation of beta catenin in patients with Rathke cleft cysts-clinical and imaging characteristics and risk of recurrence.

PURPOSE: Although Rathke cleft cysts (RCC) are benign lesions of the sellar region, recurrence is frequent after surgical treatment. Nuclear translocation of ß-catenin (NTßC), a key effector of the wnt-signaling pathway that is responsible for cell renewal, has been shown to act as a proto-oncogene and is considered to be a potential risk factor for increased recurrence in RCC. In this study, we analyzed a surgically treated cohort into patients with and without NTßC expression in order to identify clinical and imaging differences and further evaluate the risk of recurrence. METHODS: Patients with resection of RCC between 04/2001 and 11/2020 were included. Histological specimens were immunohistochemically stained for ß-catenin. Study endpoints were time to cyst recurrence (TTR) and functional outcome. Functional outcome included ophthalmological and endocrinological data. Furthermore, MRI data were assessed. RESULTS: Seventy-three patients (median age 42.3 years) with RCC underwent mainly transsphenoidal cyst resection (95.9%), 4.1% via transcranial approach. Immunohistochemical staining for ß-catenin was feasible in 61/73 (83.6%) patients, with nuclear translocation detected in 13/61 cases (21.3%). Patients with and without NTßC were equally likely to present with endocrine dysfunction before surgery (p = 0.49). Postoperative new hypopituitarism occurred in 14/73 (19.2%) patients. Preoperative visual impairment was equal in both groups (p = 0.52). Vision improved in 8/21 (33.3%) patients and visual field deficits in 22/34 (64.7%) after surgery. There was no difference in visual and perimetric outcome between patients with and without NTßC (p = 0.45 and p = 0.23, respectively). On preoperative MRI, cyst volume (9.9 vs. 8.2 cm3; p = 0.4) and evidence of hemorrhage (30.8% vs. 35.4%; p = 0.99) were equal and postoperative cyst volume decreased significantly in both groups (0.7 vs. 0.5 cm3; p < 0.0001 each). Cyst progression occurred in 13/73 (17.8%) patients after 39.3 ± 60.3 months. Cyst drainage with partial removal of the cyst wall resulted in improved recurrence-free survival without increasing the risk of complications compared with cyst fenestration alone. Patients with postoperative diabetes insipidus had an increased risk for recurrence according to multivariate analysis (p = 0.005). NTßC was evident in 4/15 patients (26.7%) and was not associated with a higher risk for recurrence (p = 0.67). CONCLUSION: Transnasal transsphenoidal cyst drainage with partial removal of the cyst wall reduces the risk of recurrence without increasing the risk of complications compared with fenestration of the cyst alone. Patients with postoperative diabetes insipidus seem to have an increased risk for recurrence. In contrast, NTßC was not associated with a higher risk of recurrence and did not provide stratification for clinically distinct patients.

Meningioma involving the superior sagittal sinus: long-term outcome after robotic radiosurgery in primary and recurrent situation.

Objective: Treatment for meningiomas involving the superior sagittal sinus (SSS) is challenging and proved to be associated with higher risks compared to other brain locations. Therapeutical strategies may be either microsurgical (sub-)total resection or adjuvant radiation, or a combination of both. Thrombosis or SSS occlusion following resection or radiosurgery needs to be further elucidated to assess whether single or combined treatment is superior. We here present tumor control and side effect data of robotic radiosurgery (RRS) in combination with or without microsurgery. Methods: From our prospective database, we identified 137 patients with WHO grade I meningioma involving the SSS consecutively treated between 2005 and 2020. Treatment decisions were interdisciplinary. Patients underwent RRS as initial/solitary treatment (group 1), as adjuvant treatment after subtotal resection (group 2), or due to recurrent tumor growth after preceding microsurgery (group 3). Positive tumor response was assessed by MRI and defined as reduction of more than 50% of volume. Study endpoints were time to recurrence (TTR), time to RRS, risk factors for decreased survival, and side effects. Overall and specific recurrence rates for treatment groups were analyzed. Side effect data included therapy-related morbidity during follow-up (FU). Results: A total of 137 patients (median age, 58.3 years) with SSS meningiomas WHO grade I were analyzed: 51 patients (37.2%) in group 1, 15 patients (11.0%) in group 2, and 71 patients (51.8%) in group 3. Positive MR (morphological response) to therapy was achieved in 50 patients (36.4%), no response was observed in 25 patients (18.2%), and radiological tumor progression was detected in 8 patients (5.8%). Overall 5-year probability of tumor recurrence was 15.8% (median TTR, 41.6 months). Five-year probabilities of recurrence were 0%, 8.3.%, and 21.5% for groups 1-3 (p = 0.06). In multivariate analysis, tumor volume was significantly associated with extent of SSS occlusion (p = 0.026) and sex (p = 0.011). Tumor volume significantly correlated with TTR (p = 0.0046). Acute sinus venous thrombosis or venous congestion-associated bleedings did not occur in any of the groups. Conclusion: RRS for grade I meningiomas with SSS involvement represents a good option as first-line treatment, occasionally also in recurrent and adjuvant scenarios as part of a multimodal treatment strategy.

Not Quite Lost in Translation: Mistranslation Alters Adaptive Landscape Topography and the Dynamics of Evolution.

Mistranslation-the erroneous incorporation of amino acids into nascent proteins-is a source of protein variation that is orders of magnitude more frequent than DNA mutation. Like other sources of nongenetic variation, it can affect adaptive evolution. We study the evolutionary consequences of mistranslation with experimental data on mistranslation rates applied to three empirical adaptive landscapes. We find that mistranslation generally flattens adaptive landscapes by reducing the fitness of high fitness genotypes and increasing that of low fitness genotypes, but it does not affect all genotypes equally. Most importantly, it increases genetic variation available to selection by rendering many neutral DNA mutations nonneutral. Mistranslation also renders some beneficial mutations deleterious and vice versa. It increases the probability of fixation of 3-8% of beneficial mutations. Even though mistranslation increases the incidence of epistasis, it also allows populations evolving on a rugged landscape to evolve modestly higher fitness. Our observations show that mistranslation is an important source of nongenetic variation that can affect adaptive evolution on fitness landscapes in multiple ways.

Interstitial photodynamic therapy for newly diagnosed glioblastoma.

PURPOSE: Innovative, efficient treatments are desperately needed for people with glioblastoma (GBM). METHODS: Sixteen patients (median age 65.8 years) with newly diagnosed, small-sized, not safely resectable supratentorial GBM underwent interstitial photodynamic therapy (iPDT) as upfront eradicating local therapy followed by standard chemoradiation. 5-aminolevulinic acid (5-ALA) induced protoporphyrin IX was used as the photosensitizer. The tumors were irradiated with light at 635 nm wavelength via stereotactically implanted cylindrical diffuser fibers. Outcome after iPDT was retrospectively compared with a positively-selected in-house patient cohort (n = 110) who underwent complete tumor resection followed by chemoradiation. RESULTS: Median progression-free survival (PFS) was 16.4 months, and median overall survival (OS) was 28.0 months. Seven patients (43.8%) experienced long-term PFS > 24 months. Median follow-up was 113.9 months for the survivors. Univariate regression revealed MGMT-promoter methylation but not age as a prognostic factor for both OS (p = 0.04 and p = 0.07) and PFS (p = 0.04 and p = 0.67). Permanent iPDT-associated morbidity was seen in one iPDT patient (6.3%). Patients treated with iPDT experienced superior PFS and OS compared to patients who underwent complete tumor removal (p < 0.01 and p = 0.01, respectively). The rate of long-term PFS was higher in iPDT-treated patients (43.8% vs. 8.9%, p < 0.01). CONCLUSION: iPDT is a feasible treatment concept and might be associated with long-term PFS in a subgroup of GBM patients, potentially via induction of so far unknown immunological tumor-controlling processes.

A simple surgical technique for sellar closure after transsphenoidal resection of pituitary adenomas in the context of risk factors for cerebrospinal fluid leaks and meningitis.

OBJECTIVE: The transsphenoidal approach is the standard for most pituitary tumors. Despite low morbidity, postoperative CSF fistulas and meningitis are specific complications. Various surgical closure techniques for intraoperative CSF (iCSF) leak and sellar reconstruction have been described. For many years the authors have applied synthetic materials for iCSF leak repair and sellar closure in a standardized fashion in their department. Here they analyze the surgical outcome as well as risk factors for iCSF leak and meningitis. METHODS: All patients with transsphenoidal resection of a pituitary adenoma performed by the same surgeon between January 2013 and December 2019 were screened retrospectively. A small amount of iCSF flow without a diaphragmatic defect was classified as a minor leak, and obvious CSF flow with or without a diaphragmatic defect was classified as a major leak. In case of iCSF leak, a fibrin- and thrombin-coated sponge was used to cover the diaphragmatic defect and another one was used for the sellar opening. A gelatin sponge was placed in the sphenoid sinus as an abutment. The primary and secondary outcomes were the number of postoperative CSF (pCSF) leaks and meningitis, respectively. Clinical, histological, and perioperative data from medical records were collected to identify risk factors for CSF leak and meningitis. RESULTS: Of 417 transsphenoidal surgeries, 359 procedures in 348 patients with a median age of 54 years were included. There were 96 iCSF leaks (26.7%; 37.5% major, 62.5% minor). In 3 of 359 cases (0.8%) a pCSF fistula occurred, requiring revision surgery in 2 patients and a lumbar drain in 1 patient. Meningitis occurred in 3 of 359 cases (0.8%). All 3 patients recovered without sequelae after antibiotic therapy. According to univariate analysis, risk factors for iCSF leak were macroadenoma (p = 0.006) and recurrent adenoma (p = 0.032). An iCSF leak was found less often in functioning adenomas (p = 0.025). In multivariate analysis recurrent tumors remained as a risk factor (p = 0.021) for iCSF leak. Patients with iCSF leak were at increased risk for a pCSF leak (p = 0.005). A pCSF leak in turn represented the key risk factor for meningitis (p = 0.033). CONCLUSIONS: Patients with macroadenomas and recurrent adenomas are especially at risk for iCSF leak. An iCSF leak in turn increases the risk for a pCSF leak, which carries the risk for meningitis. The authors' surgical technique leads to a very low rate of pCSF leaks and meningitis without using autologous graft materials. Hence, this technique is safe and improves patient comfort by avoiding the disadvantages of autologous graft harvesting.

Headache characteristics and postoperative course in Chiari I malformation.

BACKGROUND: Chiari I malformation typically presents with cough headache. However, migraine-like or tension-type-like headaches may also occur. There are limited publications on Chiari I malformation-associated headache semiologies and the effect of foramen magnum decompression on different headache types. METHODS: A retrospective analysis complemented by structured phone interviews was performed on 65 patients with Chiari I malformation, treated at our hospital between 2010 and 2021. Headache semiology (according to ICHD-3), frequency, intensity, and radiological characteristics were evaluated pre- and postoperatively. RESULTS: We included 65 patients. 38 patients were female and 27 male. Mean age was 43.9 ± 15.7 years. Headache was predominant in 41 patients (63.0%). Twenty-one patients had cough headache and 20 had atypical headache (12 migrainous, eight tension-type headache-like). Thirty-five patients with headache underwent surgery. Frequency, intensity, and analgesic use was significantly reduced in cough headache (p < 0.001). Atypical headaches improved less (p = 0.004 to 0.176). Exploratory analysis suggested that larger preoperative tonsillar descent correlated with larger postoperative headache intensity relief (p = 0.025). CONCLUSION: Decompression was effective in Chiari I malformation-related cough headache. Atypical headache responded less well, and the causal relation with Chiari I malformation remains uncertain. For atypical headache, decompression should only be considered after failed appropriate preventive therapy and within an interdisciplinary approach involving a neurologist.

Interstitial Photodynamic Therapy Using 5-ALA for Malignant Glioma Recurrences.

Interstitial photodynamic therapy (iPDT) using 5-aminolevulinic acid (5-ALA)-induced protoporphyrin IX (PpIX) as a cytotoxic photosensitizer could be a feasible treatment option for malignant gliomas. In a monocentric cohort of consecutive patients treated between 2006 and 2018, a risk profile analysis of salvage iPDT for local malignant glioma recurrences and associated outcome measures are presented here. It was considered indicated in patients with circumscribed biopsy-proven malignant glioma recurrences after standard therapy, if not deemed eligible for safe complete resection. A 3D treatment-planning software was used to determine the number and suitable positions of the cylindrical diffusing fibers placed stereotactically to ensure optimal interstitial irradiation of the target volume. Outcome measurements included the risk profile of the procedure, estimated time-to-treatment-failure (TTF), post-recurrence survival (PRS) and prognostic factors. Forty-seven patients were treated, of which 44 (median age, 49.4 years, range, 33.4-87.0 years, 27 males) could be retrospectively evaluated. Recurrent gliomas included 37 glioblastomas (WHO grade IV) and 7 anaplastic astrocytomas (WHO grade III). Thirty (68.2%) tumors were O-6-methylguanine-DNA methyltransferase (MGMT)-methylated, 29 (65.9%)-isocitrate dehydrogenase (IDH)-wildtype. Twenty-six (59.1%) patients were treated for their first, 9 (20.5%)-for their second, 9 (20.5%)-for the third or further recurrence. The median iPDT target volume was 3.34 cm3 (range, 0.50-22.8 cm3). Severe neurologic deterioration lasted for more than six weeks in one patient only. The median TTF was 7.1 (95% confidence interval (CI), 4.4-9.8) months and the median PRS was 13.0 (95% CI, 9.2-16.8) months. The 2- and 5-year PRS rates were 25.0% and 4.5%, respectively. The treatment response was heterogeneous and not significantly associated with patient characteristics, treatment-related factors or molecular markers. The promising outcome and acceptable risk profile deserve further prospective evaluation particularly to identify mechanisms and prognostic factors of favorable treatment response.

Gene expression noise can promote the fixation of beneficial mutations in fluctuating environments.

Nongenetic phenotypic variation can either speed up or slow down adaptive evolution. We show that it can speed up evolution in environments where available carbon and energy sources change over time. To this end, we use an experimentally validated model of Escherichia coli growth on two alternative carbon sources, glucose and acetate. On the superior carbon source (glucose), all cells achieve high growth rates, while on the inferior carbon source (acetate) only a small fraction of the population manages to initiate growth. Consequently, populations experience a bottleneck when the environment changes from the superior to the inferior carbon source. Growth on the inferior carbon source depends on a circuit under the control of a transcription factor that is repressed in the presence of the superior carbon source. We show that noise in the expression of this transcription factor can increase the probability that cells start growing on the inferior carbon source. In doing so, it can decrease the severity of the bottleneck and increase mean population fitness whenever this fitness is low. A modest amount of noise can also enhance the fitness effects of a beneficial allele that increases the fraction of a population initiating growth on acetate. Additionally, noise can protect this allele from extinction, accelerate its spread, and increase its likelihood of going to fixation. Central to the adaptation-enhancing principle we identify is the ability of noise to mitigate population bottlenecks, particularly in environments that fluctuate periodically. Because such bottlenecks are frequent in fluctuating environments, and because periodically fluctuating environments themselves are common, this principle may apply to a broad range of environments and organisms.

Resting-state fMRI detects alterations in whole brain connectivity related to tumor biology in glioma patients.

BACKGROUND: Systemic infiltration of the brain by tumor cells is a hallmark of glioma pathogenesis which may cause disturbances in functional connectivity. We hypothesized that aggressive high-grade tumors cause more damage to functional connectivity than low-grade tumors. METHODS: We designed an imaging tool based on resting-state functional (f)MRI to individually quantify abnormality of functional connectivity and tested it in a prospective cohort of patients with newly diagnosed glioma. RESULTS: Thirty-four patients were analyzed (World Health Organization [WHO] grade II, n = 13; grade III, n = 6; grade IV, n = 15; mean age, 48.7 y). Connectivity abnormality could be observed not only in the lesioned brain area but also in the contralateral hemisphere with a close correlation between connectivity abnormality and aggressiveness of the tumor as indicated by WHO grade. Isocitrate dehydrogenase 1 (IDH1) mutation status was also associated with abnormal connectivity, with more alterations in IDH1 wildtype tumors independent of tumor size. Finally, deficits in neuropsychological performance were correlated with connectivity abnormality. CONCLUSION: Here, we suggested an individually applicable resting-state fMRI marker in glioma patients. Analysis of the functional connectome using this marker revealed that abnormalities of functional connectivity could be detected not only adjacent to the visible lesion but also in distant brain tissue, even in the contralesional hemisphere. These changes were associated with tumor biology and cognitive function. The ability of our novel method to capture tumor effects in nonlesional brain suggests a potential clinical value for both individualizing and monitoring glioma therapy.

Spinal intradural extramedullary arachnoid cysts in adults-operative therapy and clinical outcome.

BACKGROUND: Spinal arachnoid cysts (SAC) are rare mostly idiopathic intradural lesions with compression of the spinal cord and clinical signs of radiculo- and/or myelopathy. We retrospectively analyzed radiological and clinical characteristics of patients with surgical treatment of SAC including a subgroup evaluation of long-term outcome and QoL. METHOD: Patients with SAC treated between 1993 and 2017 were evaluated. Craniocaudal (c.c.) and anteroposterior (a.p) cyst diameters were measured pre- and post-OP. McCormick and Odom score for myelopathy, general outcome and QoL (SF-36, EORTC-QLQ30) were recorded. RESULTS: A total of 72 patients (female:male = 1.9:1) were analyzed with mean FU of 44.8 ± 60 months (long-term data from 25 patients with FU 78.2 ± 63.9 months). All had surgery due to solitary cysts: 10 cervical (13.9%), 45 thoracic (62.5%), and 17 lumbosacral (23.6%), the majority (79.2%) located dorsally. Main symptoms were gait disturbance (80%), dysesthesia (64%) and paresis (80%). Patients had (hemi-)laminectomy with cyst fenestration in 48 (66.7%) and complete resection in 18 cases (25.0%). Four cases (5.5%) were treated by cystoperitoneal shunt, 2 by marsupialization (2.8%). In total, 11 revisions were necessary in 9/72 (12.5%) patients (one patient underwent 3 revisions). Two patients were reoperated for wound revision/epidural hematoma (each n = 1). Seven patients needed additional cyst wall resection after 1.5-31.0 months due to insufficient cyst shrinking and persistent clinical symptoms after first surgery; most of the cysts were multiple septated and of post-hemorrhagic origin. The mean c.c. size decreased from 5.2 ± 3.7 cm pre-OP to 2.7 ± 3.9 cm (p < 0.05); the a.p. diameter decreased from 1.0 ± 0.5 cm to 0.3 ± 0.3 cm (p < 0.0001) without significant differences between fenestration and resection. McCormick and Odom scores revealed improved symptoms, particularly of gait disturbance, sensory deficits, and general performance. Long-term FU displayed satisfying QoL performance without differences of fenestration or resection. CONCLUSION: SAC mostly affect women and are predominantly located in the thoracic spine, becoming apparent with clinical myelopathy. For cysts without intracystic septae and compartments, both fenestration and resection of the cyst wall provided significant reduction of cyst size and clinical improvement.

The role of recombination, niche-specific gene pools and flexible genomes in the ecological speciation of bacteria.

Bacteria diversify into genetic clusters analogous to those observed in sexual eukaryotes, but the definition of bacterial species is an ongoing problem. Recent work has focused on adaptation to distinct ecological niches as the main driver of clustering, but there remains debate about the role of recombination in that process. One view is that homologous recombination occurs too rarely for gene flow to constrain divergent selection. Another view is that homologous recombination is frequent enough in many bacterial populations that barriers to gene flow are needed to permit divergence. Niche-specific gene pools have been proposed as a general mechanism to limit gene flow. We use theoretical models to evaluate additional hypotheses that evolving genetic architecture, specifically the effect sizes of genes and gene gain and loss, can limit gene flow between diverging populations. Our model predicts that (a) in the presence of gene flow and recombination, ecological divergence is concentrated in few loci of large effect and (b) high rates of gene flow plus recombination promote gene loss and favor the evolution of niche-specific genes. The results show that changing genetic architecture and gene loss can facilitate ecological divergence, even without niche-specific gene pools. We discuss these results in the context of recent studies of sympatric divergence in microbes.

Inflammatory Markers in Serum and Cerebrospinal Fluid for Early Detection of External Ventricular Drain-associated Ventriculitis in Patients With Subarachnoid Hemorrhage.

BACKGROUND: External ventricular drain (EVD)-associated ventriculitis is a serious complication. Early diagnosis can be difficult particularly in critically ill patients with aneurysmal subarachnoid hemorrhage (aSAH). We examined the diagnostic potential of standard serum and cerebrospinal fluid (CSF) biomarkers to differentiate between EVD-associated infections and aseptic courses in patients with aSAH. MATERIALS AND METHODS: We retrospectively evaluated the levels of inflammatory markers in serum (white blood cell count, percentage of neutrophils [sN%], and procalcitonin) and CSF (total leukocyte count [CSFTLC], CSFglucose, CSF/serumglucose ratio, CSF total protein [CSFTP]) of 63 consecutive patients with aSAH. Receiver operating characteristic curves and the area-under-the-curve (AUC) were calculated to detect the diagnostic potential, optimized threshold, sensitivity (SE), specificity (SP), + likelihood ratio (LR), and -LR of each biomarker. RESULTS: Of all patients, 17 (27%) developed an EVD-associated ventriculitis within a mean of 7.8±2.3 days after implantation. sN% had a very good diagnostic potential (AUC=0.900, SE=70.0%, SP=100%), followed by the CSFTLC with good diagnostic potential (AUC=0.841, SE=75.0%, SP=88.5%), and the CSFTP with moderate diagnostic potential (AUC=0.772, SE=73.3%, SP=76.0%). sN% higher than 70% and a CSFTLC higher than 635/µL were highly associated with the diagnosis of ventriculitis (+LR=∞ and 6.5), sN%<70% or a CSFTLC<635 made a diagnosis of ventriculitis unlikely (-LR=0.3 and 0.28). CONCLUSIONS: Routine determination of N% and CSFTLC are useful to distinguish ventriculitis from aseptic courses in the acute phase after aSAH and regardless of the bacteriological test result.

Cell compaction influences the regenerative potential of passaged bovine articular chondrocytes in an ex vivo cartilage defect model.

The loss and degradation of articular cartilage tissue matrix play central roles in the process of osteoarthritis (OA). New models for evaluating cartilage repair/regeneration are thus of great value for transferring various culture systems into clinically relevant situations. The repair process can be better monitored in ex vivo systems than in in vitro cell cultures. I have therefore established an ex vivo defect model prepared from bovine femoral condyles for evaluating cartilage repair by the implantation of cells cultured in various ways, e.g., monolayer-cultured cells or suspension or pellet cultures of articular bovine chondrocytes representing different cell compactions with variable densities of chondrocytes. I report that the integrin subunit α10 was significantly upregulated in suspension-cultured bovine chondrocytes at passage P2 compared with monolayer-cultured cells at P1 (p = 0.0083) and P2 (p < 0.05). Suspension-cultured cells did not promote cartilage repair when compared with implanted monolayer-cultured chondrocytes and pellets: 24.0 ± 0.66% for suspension cells, 46.4 ± 2.9% for monolayer cells, and 127.64 ± 0.90% for pellets (p < 0.0001) of the original defect volume (percentage of defect). Additional cultivation with chondrogenesis-promoting growth factors TGF-ß1 and BMP-2 revealed an enhancing effect on cartilage repair in all settings. The advantage and innovation of this system over in vitro differentiation (e.g., micromass, pellet) assays is the possibility of examining and evaluating cartilage regeneration in an environment in which implanted cells are embedded within native surrounding tissue at the defect site. Such ex vivo explants might serve as a better model system to mimic clinical situations.