Cortical Catecholamine Secretion Following Intravenous Nitroprusside Infusion: A Voltammetric Study

Intravenous administration of sodium nitroprusside (NP) decreases blood pressure and activates noradrenergic neurons in the locus coeruleus (LC). Microdialysis studies have shown that NP infusion is accompanied by increased extracellular concentrations of norepinephrine (NE) in the medial prefrontal cortex. The present study used in vivo voltammetry to obtain a finer temporal analysis of the NP-induced changes in the extracellular concentrations of catecholamine-like compounds in the LC terminal fields in the rat medial prefrontal cortex. Intravenous infusion of rats with NP caused a rapid decrease in blood pressure that lasted for the duration of the infusion but rapidly reversed when the infusion was terminated. After a delay of between about 2 and 8 min (mean 5 min), there was an increase in extracellular concentrations of a NE-like substance. Presumed cortical release of NE lasted for several minutes but had almost returned to baseline by the time the NP infusion was terminated at 15 min. In many cases, the first peak was followed by a second one, usually of smaller amplitude but more prolonged than the first one. There was no clear response to the cessation of infusion of NP. The time course of the initial response is comparable to the previously reported electrophysiological response of LC-NE neurons to NP. In rats treated with DSP-4 to deplete cortical NE, blood pressure was reduced as in untreated rats, but no voltammetric response to NP infusion was observed. These results suggest that activation of the NE-LC neurons by NP results in a delayed synaptic release of NE in the cerebral cortex which attenuates within several minutes.     

Prediction of mortality in severely injured patients with facial bone fractures

Purpose

Identify the most common concomitant injuries associated with facial trauma, and compare the efficacy of various scoring systems in estimation of mortality risks in this category of patients.

Methods

The study evaluated patients with facial and concomitant injuries, who received the multidisciplinary treatment in a specialized trauma hospital. Values of New Injury Severity Score, Glasgow Coma Scale, Facial Injury Severity Scale, age, and length of hospital stay were statistically analysed to determine presence of relationships between these indicators and define factors that significantly associated with lethal outcome.

Results

During 6-year observation period, 719 patients were treated with multiple or combined maxillofacial trauma, brain injuries and polytrauma. Mainly with isolated midface bones (49.7%), pan-facial (34.6%), mandible (12.9%), and frontal bone and walls (2.8%) fractures. Mortality was (2.2%). The mortality rates in patients with severe pan-facial fractures were higher (p?=?0.008) than in single anatomical area (6% vs 1.5%). Age, GCS, and NISS were the most reliable indicator of lethal outcome.

Conclusion

Age, Glasgow Coma Scale and New Injury Severity Score main factors, that predicts lethal outcome with high accuracy. New Injury Severity Score value?≥?41 is a critical level for survival prognosis and should be considered in treatment planning and management of this category of patients.

     

Primary vs. delayed perineal proctectomy—there is no free lunch

Purpose

Perineal wound complications associated with anorectal excision are associated with prolonged wound healing and readmission. In order to avoid these problems, the surgeon may choose to leave the anorectum in situ. The purpose of this study is to compare complications and outcomes after primary vs. delayed anorectum removal.

Methods

A retrospective review of all patients undergoing proctectomy or proctocolectomy with permanent stoma between 2004 and 2014 in a single tertiary institution was conducted.

Results

During the study period, we identified 117 proctectomy patients; 69 (59%) patients had anorectum removed at index operation and 41% had the anorectum left in place. Patients with retained anorectum developed pelvic abscess significantly more frequently as compared to the other group (23 vs. 4%, p = 0.003). In patients with primary anorectum removal, 22 (32%) had perineal complications and 10 (15%) required reoperations. In patients with retained anorectum, 12 patients (25%) came back for delayed perineal proctectomy at a mean time of 277 days after the index operation; 7 of those (58%) developed postoperative wound complications. There was no difference in time to perineal wound healing between primary and delayed perineal proctectomy group (154 vs. 211 days, p = 0.319).

Conclusion

Surgery involving the distal rectum is associated with a significant number of infectious perineal complications. Although leaving the anorectum in place avoids a primary perineal wound, both approaches are associated with a significant number of complications including reoperation.

     

Mechanical and Chemical Characterisation of TiN and AlTiSiN Coatings on a LPBF Processed IN718 Substrate

Wear-resistant coatings development is progressively increasing steeply due to their advantages when applied to mechanical components subjected to abrasive and destructive environments. Titanium nitride (TiN) coating is typically used to enlarge tools and components’ service life and improve their surface quality. On the other hand, AlTiSiN coating intends to be applied to more aggressive environments such as spatial satellites components exposed to solar radiation, extremely high temperatures, and random particles impact. In this work, specimens of Inconel 718 (IN718) were fabricated via laser powder bed fusion (LPBF), and physical vapour deposition (PVD)-deposited with TiN and AlTiSiN as coatings to mechanically and chemically characterise their surface. In this respect, microhardness testing and chemical analysis via glow discharge optical emission spectroscopy (GDOES) were performed. Later, roughness and wear behaviour analyses were carried out to evaluate the mechanical performance of both coatings and their surface and morphological features. The experimental observations allowed the analysis of both studied coatings by comparing them with the substrate processed via LPBF.     

Amyloid β concentrations and stable isotope labeling kinetics of human plasma specific to central nervous system amyloidosis

Introduction

Cerebrospinal fluid analysis and other measurements of amyloidosis, such as amyloid-binding positron emission tomography studies, are limited by cost and availability. There is a need for a more practical amyloid β (Aβ) biomarker for central nervous system amyloid deposition.

Spatiotemporal activity patterns during respiratory rhythmogenesis in the rat ventrolateral medulla

One of the most important brain rhythms is that which generates involuntary breathing movements. The lower brain stem contains neural circuitry for respiratory rhythm generation in mammals. To date, microsectioning and selective lesioning studies have revealed anatomical regions necessary for respiratory rhythmogenesis. Although respiratory neurons distributed within these regions can be identified by their firing patterns in different phases of the respiratory cycle, conventional electrophysiology techniques have limited the study of spatial organization within this network. Optical imaging techniques offer the potential for monitoring the spatiotemporal activity of large groups of neurons simultaneously. Using high-speed voltage-sensitive dye imaging and spatial correlation analysis in an arterially perfused in situ preparation of the juvenile rat, we determined the spatial distribution of respiratory neuronal activity in a region of the ventrolateral respiratory group containing the pre-B?tzinger complex (pBC) during spontaneous eupneic breathing. While distinctly pre- and postinspiratory-related responses were spatially localizable on length scales less than 100 microm, we found the studied area on whole exhibited a spatial mixture of phase-spanning and postinspiratory-related activity. Additionally, optical recordings revealed significant widespread hyperpolarization, suggesting inhibition in the same region during expiration. This finding is consistent with the hypothesis that inhibitory neurons play a crucial role in the inspiration-expiration phase transition in the pBC. To our knowledge this is the first optical imaging of a near fully intact in situ preparation that exhibits both eupneic respiratory activity and functional reflexes.     

Method for transforming CT images for attenuation correction in PET/CT imaging

A tube-voltage-dependent scheme is presented for transforming Hounsfield units (HU) measured by different computed tomography (CT) scanners at different x-ray tube voltages (kVp) to 511 keV linear attenuation values for attenuation correction in positron emission tomography (PET) data reconstruction. A Gammex 467 electron density CT phantom was imaged using a Siemens Sensation 16-slice CT, a Siemens Emotion 6-slice CT, a GE Lightspeed 16-slice CT, a Hitachi CXR 4-slice CT, and a Toshiba Aquilion 16-slice CT at kVp ranging from 80 to 140 kVp. All of these CT scanners are also available in combination with a PET scanner as a PET/CT tomograph. HU obtained for various reference tissue substitutes in the phantom were compared with the known linear attenuation values at 511 keV. The transformation, appropriate for lung, soft tissue, and bone, yields the function 9.6 x 10(-5). (HU+ 1000) below a threshold of approximately 50 HU and a (HU+ 1000)+b above the threshold, where a and b are fixed parameters that depend on the kVp setting. The use of the kVp-dependent scaling procedure leads to a significant improvement in reconstructed PET activity levels in phantom measurements, resolving errors of almost 40% otherwise seen for the case of dense bone phantoms at 80 kVp. Results are also presented for patient studies involving multiple CT scans at different kVp settings, which should all lead to the same 511 keV linear attenuation values. A linear fit to values obtained from 140 kVp CT images using the kVp-dependent scaling plotted as a function of the corresponding values obtained from 80 kVp CT images yielded y = 1.003 x -0.001 with an R2 value of 0.999, indicating that the same values are obtained to a high degree of accuracy.     

Direct Mass Spectrometry Differentiation of Ectopic and Eutopic Endometrium in Patients with Endometriosis

Study Objective

To introduce a method for the rapid assessment of endometriotic tissues using direct mass spectrometry (MS)-based lipidomics.