Posterior fossa meningioma (surgical experiences)

Introduction: Meningioma is a common tumor that represents about 30% of all intracranial tumors. Posterior fossa location of the tumor is uncommon. It can be classified according to the location in the posterior fossa into cerebellopontine angle, clival, petroclival, convexity, tentorial and foramen magnum. Different surgical approaches are used to excise these tumors.Aim of the study: Was to study different aspects of posterior fossa meningioma regarding location, histology, surgical approaches and outcome.Methods: Retrospective study including 20 patients diagnosed with posterior fossa meningioma was included in the study. Data were obtained from the files of the patients and were analyzed. All patients had preoperative complete general and neurological examination, MRI of the brain with and without Gadolinium. Different surgical approaches were utilized in the study depending on the tumor location and the surgeon’s preference. Postoperatively, all patients had a postoperative CT scan of the brain with contrast. Some patients had also MRI of the brain with and without Gadolinium.Results: Fifteen of the patients were females and 5 were males. The age ranged from 35 to 69. Symptoms included headache (75%), cerebellar manifestations (60%), cranial nerve affection (40%) and hearing disturbances (15%). Most of the cases (50%) were cerebellopontine angle meningioma while the least (5%) were foramen magnum meningioma. Surgical approaches used included retrosigmoid approach (50%), transpetrosal approach (30%) and transcondylar approach (20%). Tumor removal was total in 60% of cases and partial in 40%. Postoperative mortality was present in 5% of cases. Morbidity included decreased level of consciousness, cranial nerve palsy and wound infection.Conclusion: Retrosigmoid approach is effectively and safely used for cerebellopontine angle meningioma, convexity menigioma and lateral tentorial meningioma extending inferiorly to the posterior fossa. Suboccipital approach can be used safely for posterior foramen magnum meningioma. Clival and petroclival meningioma carry a high morbidity incidence.Keywords: Meningioma; Posterior fossa; Retrosigmoid approach; Transpetrosal approac

Oscillatory surface rheotaxis of swimming E. coli bacteria

Bacterial contamination of biological conducts, catheters or water resources is a major threat to public health and can be amplified by the ability of bacteria to swim upstream. The mechanisms of this rheotaxis, the reorientation with respect to flow gradients, often in complex and confined environments, are still poorly understood. Here, we follow individual E. coli bacteria swimming at surfaces under shear flow with two complementary experimental assays, based on 3D Lagrangian tracking and fluorescent flagellar labelling and we develop a theoretical model for their rheotactic motion. Three transitions are identified with increasing shear rate: Above a first critical shear rate, bacteria shift to swimming upstream. After a second threshold, we report the discovery of an oscillatory rheotaxis. Beyond a third transition, we further observe coexistence of rheotaxis along the positive and negative vorticity directions. A full theoretical analysis explains these regimes and predicts the corresponding critical shear rates. The predicted transitions as well as the oscillation dynamics are in good agreement with experimental observations. Our results shed new light on bacterial transport and reveal new strategies for contamination prevention.Comment: 12 pages, 5 figure

Incorporating the social dimension into hydrogeochemical investigations for rural development: the Bir Al-Nas approach for socio-hydrogeology

A replicable multidisciplinary approach is presented for science-based groundwater management practices: Bir Al-Nas (Bottom-up IntegRated Approach for sustainabLe grouNdwater mAnagement in rural areaS). This approach provides a practical example of the concept of “socio-hydrogeology”, a way of incorporating the social dimension into hydrogeological investigations, as reinforced by the translation of the Arabic bir al-nas: “the people’s well”. To achieve this, hydrogeologists act as “social hydrologists” during their monitoring activities, which often bring them into contact with local communities and end users (and polluters) of water. Not only can they retrieve reliable information about traditional know-how and local issues, but they can also change the public perception of science/scientists to create the basis for mutual collaboration and understanding in view of implementing improved integrated groundwater management. The final outcomes are expected to be an increased awareness of communities at the local level and a clear understanding of their water issues and needs from the very early stages of the investigation. Although the importance of using such methods in groundwater analysis and management is widely recognized, hydrogeological investigations are currently dominated by sectorial approaches that are easier to implement but less sustainable. The pressure of population growth, the shift towards more water-dependent economies, climate change and its impact on water availability will require scientists to use a more integrated approach, such as Bir Al-Nas, when dealing with increasing water pollution and water-scarcity issues.A replicable multidisciplinary approach is presented for science-based groundwater management practices: Bir Al-Nas (Bottom-up IntegRated Approach for sustainabLe grouNdwater mAnagement in rural areaS). This approach provides a practical example of the concept of "socio-hydrogeology", a way of incorporating the social dimension into hydrogeological investigations, as reinforced by the translation of the Arabic bir al-nas: "the people's well". To achieve this, hydrogeologists act as "social hydrologists" during their monitoring activities, which often bring them into contact with local communities and end users (and polluters) of water. Not only can they retrieve reliable information about traditional know-how and local issues, but they can also change the public perception of science/scientists to create the basis for mutual collaboration and understanding in view of implementing improved integrated groundwater management. The final outcomes are expected to be an increased awareness of communities at the local level and a clear understanding of their water issues and needs from the very early stages of the investigation. Although the importance of using such methods in groundwater analysis and management is widely recognized, hydrogeological investigations are currently dominated by sectorial approaches that are easier to implement but less sustainable. The pressure of population growth, the shift towards more water-dependent economies, climate change and its impact on water availability will require scientists to use a more integrated approach, such as Bir Al-Nas, when dealing with increasing water pollution and water-scarcity issues

Altered Small-World Brain Networks in Schizophrenia Patients during Working Memory Performance

Impairment of working memory (WM) performance in schizophrenia patients (SZ) is well-established. Compared to healthy controls (HC), SZ patients show aberrant blood oxygen level dependent (BOLD) activations and disrupted functional connectivity during WM performance. In this study, we examined the small-world network metrics computed from functional magnetic resonance imaging (fMRI) data collected as 35 HC and 35 SZ performed a Sternberg Item Recognition Paradigm (SIRP) at three WM load levels. Functional connectivity networks were built by calculating the partial correlation on preprocessed time courses of BOLD signal between task-related brain regions of interest (ROIs) defined by group independent component analysis (ICA). The networks were then thresholded within the small-world regime, resulting in undirected binarized small-world networks at different working memory loads. Our results showed: 1) at the medium WM load level, the networks in SZ showed a lower clustering coefficient and less local efficiency compared with HC; 2) in SZ, most network measures altered significantly as the WM load level increased from low to medium and from medium to high, while the network metrics were relatively stable in HC at different WM loads; and 3) the altered structure at medium WM load in SZ was related to their performance during the task, with longer reaction time related to lower clustering coefficient and lower local efficiency. These findings suggest brain connectivity in patients with SZ was more diffuse and less strongly linked locally in functional network at intermediate level of WM when compared to HC. SZ show distinctly inefficient and variable network structures in response to WM load increase, comparing to stable highly clustered network topologies in HC

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Neuroprotective effect of N-acetylcysteine against cisplatin-induced toxicity in rat brain by modulation of oxidative stress and inflammation

Wessam M Abdel-Wahab,1,2 Farouzia I Moussa1 1Department of Zoology, Faculty of Science, University of Alexandria, Alexandria, Egypt; 2Department of Basic Sciences/Biology Unit, Deanship of Preparatory Year and Supporting Studies, Imam Abdulrahaman Bin Faisal University, Dammam, Saudi Arabia Background: Neurotoxicity is a major obstacle to the effectiveness of cisplatin (CDDP) in cancer chemotherapy. Oxidative stress and inflammation are considered to be the major mechanisms involved in CDDP-induced neurotoxicity. The rationale of our study was to investigate the efficacy of N-acetylcysteine (NAC) at two different doses in the management of CDDP-induced toxicity in rat brain by monitoring its antioxidant and anti-inflammatory effects.Methods: Thirty-five male rats were divided into five groups (n=7) as follows: control group (0.5 mL saline), NAC100 group (100 mg/kg), CDDP group (8 mg/kg), NAC50-CDDP group (50 mg/kg NAC and 8 mg/kg CDDP), and NAC100-CDDP group (100 mg/kg NAC and 8 mg/kg CDDP). NAC was administered for 20 consecutive days, while CDDP was injected once on day 15 of the treatment protocol.Results: The neurotoxicity of CDDP was evidenced by a marked increase in acetylcholinesterase and monoamine oxidase activities. It also induced oxidative stress as indicated by increased levels of lipid peroxidation, nitric oxide, and protein carbonyl with a concomitant decline in reduced glutathione, glutathione peroxidase, glutathione S-transferase, superoxide dismutase, and catalase in the brain. Moreover, CDDP enhanced the synthesis of pro-inflammatory cytokines such as tumor necrosis factor-α, interleukin-1β, and interleukin-6. Treatment with NAC at the two selected doses significantly attenuated CDDP-induced changes in the brain cholinergic function, improved the brain oxidant/antioxidant status, and also reversed the overproduction of pro-inflammatory cytokines in brain and serum.Conclusion: NAC could serve as an appropriate and safe complementary therapeutic agent to attenuate the toxicity of CDDP in the brain and therefore improve its outcomes in chemotherapy. Keywords: cisplatin, neurotoxicity, brain, N-acetylcysteine, rat

Synergistic protective effect of N-acetylcysteine and taurine against cisplatin-induced nephrotoxicity in rats

Wessam M Abdel-Wahab,1,2 Farouzia I Moussa,2 Najwa A Saad3 1Department of Biology, College of Medicine, University of Dammam, Dammam, Saudi Arabia; 2Department of Zoology, Faculty of Science, University of Alexandria, Alexandria, Egypt; 3Department of Zoology, Faculty of Science, University of Benghazi, Benghazi, Libya Abstract: Cisplatin (cis-diaminedichloroplatinum II; CDDP) is an effective anticancer drug, but it has limitations because of its nephrotoxicity. This study investigates the protective effect of N-acetylcysteine (NAC) and taurine (TAU), both individually and in combination, against CDDP nephrotoxicity in rats. For this purpose, 48 male rats were assigned into eight groups (n=6) as follows: 1) control group, 2) NAC group, 3) TAU group, 4) NAC–TAU group, 5) CDDP group, 6) CDDP–NAC group, 7) CDDP–TAU group, and 8) CDDP–NAC–TAU group. Cisplatin was administered as a single intraperitoneal injection at a concentration of 6 mg/kg. Three days after CDDP administration, NAC (50 mg/kg) and/or TAU (50 mg/kg) were administered three times weekly for four consecutive weeks. Kidney function markers in serum, urinary glucose and protein, as well as oxidant and antioxidant parameters in renal tissue were assessed. Administration of CDDP significantly elevated urinary glucose and protein, as well as serum creatinine, urea, and uric acid. Moreover, CDDP enhanced lipid peroxidation and suppressed the major enzymatic antioxidants in the kidney tissue. Treatment with NAC or TAU protected against the alterations in the serum, urine, and renal tissue when used individually along with CDDP. Furthermore, a combined therapy of both was more effective in ameliorating CDDP-induced nephrotoxicity, which points out to their synergistic effect. Keywords: cisplatin, nephrotoxicity, oxidative stress, N-acetylcysteine, taurin