Early results using cerebral perfusion pressure (CPP) management techniques in persons with traumatic brain injury indicate that treatment directed at CPP is superior to traditional techniques ...focused on intracranial pressure (ICP) management. The authors have continued to refine management techniques directed at CPP maintenance. One hundred fifty-eight patients with Glasgow Coma Scale (GCS) scores of 7 or lower were managed using vascular volume expansion, cerebrospinal fluid drainage via ventriculostomy, systemic vasopressors (phenylephrine or norepinephrine), and mannitol to maintain a minimum CPP of at least 70 mm Hg. Detailed outcomes and follow-up data bases were maintained. Barbiturates, hyperventilation, and hypothermia were not used. Cerebral perfusion pressure averaged 83 +/- 14 mm Hg; ICP averaged 27 +/- 12 mm Hg; and mean systemic arterial blood pressure averaged 109 +/- 14 mm Hg. Cerebrospinal fluid drainage averaged 100 +/- 98 cc per day. Intake (6040 +/- 4150 cc per day) was carefully titrated to output (5460 +/- 4000 cc per day); mannitol averaged 188 +/- 247 g per day. Approximately 40% of these patients required vasopressor support. Patients requiring vasopressor support had lower GCS scores than those not requiring vasopressors (4.7 +/- 1.3 vs. 5.4 +/- 1.2, respectively). Patients with vasopressor support required larger amounts of mannitol, and their admission ICP was 28.7 +/- 20.7 versus 17.5 +/- 8.6 mm Hg for the nonvasopressor group. Although the death rate in the former group was higher, the outcome quality of the survivors was the same (Glasgow Outcome Scale scores 4.3 +/- 0.9 vs. 4.5 +/- 0.7). Surgical mass lesion patients had outcomes equal to those of the closed head-injury group. Mortality ranged from 52% of patients with a GCS score of 3 to 12% of those with a GCS score of 7; overall mortality was 29% across GCS categories. Favorable outcomes ranged from 35% of patients with a GCS score of 3 to 75% of those with a GCS score of 7. Only 2% of the patients in the series remained vegatative and if patients survived, the likelihood of their having a favorable recovery was approximately 80%. These results are significantly better than other reported series across GCS categories in comparisons of death rates, survival versus dead or vegetative, or favorable versus nonfavorable outcome classifications (Mantel-Haenszel chi 2, p < 0.001). Better management could have improved outcome in as many as 35% to 50% of the deaths.
•The reconstructed primary forest cover served as a main input for the ABM.•With regard to mining, the produced copper volume has the highest impact on the extent of deforestation.•The quality of ...ores and different types of biomass are of minor significance.•Natural succession can reduce the destruction of forests by up to 75%.•In the majority of cases deforestation for agriculture exceeds the impact of mining.
This study deals with the historical impacts of mining as a result of the economic development in Eastern Asia. It focuses on landscape changes caused by the emerging copper mining industry in China's south east provinces. Since the ecological aftermath has never been documented in Chinese history, a reconstruction of dynamic landscape processes is performed. A key region for this reconstruction are the mining areas in Yunnan province. This province was the most important supplying region of copper in China during the early and mid Qing dynasty (1725–1855).
Predictive modeling of the primary vegetation in combination with dynamic agent-based reconstructions have been performed to analyze and to understand deforestation processes. Therefore a time-discrete balance between biomass removal and renewal has been carried out to characterize different periods of landscape degradation, biodiversity and agriculture. Besides the reconstruction, explanatory and experimental results have been compiled to assess the ecological impacts of mining during this period.
An ‘Evaludation’ of the model was performed in order to verify the applied concepts and test the integration of data as well as the conclusive generation of results. Our calculations show that while deforestation for mining was severe in the 18th and 19th century, rising populations and agricultural reclamation had a bigger impact on the clearance of forests. In addition, quantitative data for the ecological succession show that deforestation was reduced by up to 75% due to the provision of regrowing biomass. Deforested areas around the mines were either completely destroyed or of high biodiversity due to the abundance of heterogenous vegetation communities within small spaces. Lastly, two extreme scenarios were calculated which covered all positive and negative triggers of deforestation. These calculations served as reference data to evaluate model's quality: our model outputs lie within the range of comparable studies but underestimate the total deforestation reported and yet some uncertainties regarding forest fires and other uses of biomass remain. This study has led to a more holistic understanding of the interactions between copper mining and landscape ecology in Chinese history.
Contact heat evoked potentials (CHEPs) have become an acknowledged research tool in the assessment of the integrity of the nociceptive system and gained importance in the diagnostic work-up of ...patients with suspected small fiber neuropathy. For the latter, normative values for CHEP amplitude and latency are indispensable for a clinically meaningful interpretation of the results gathered in patients. To this end, CHEPs were recorded in 100 healthy subjects over a wide age range (20-80 years) and from three different dermatomes of the lower extremities (L2, L5, and S2). A normal baseline (35-52 °C) and increased baseline stimulation (42-52 °C) were applied. Statistical analysis revealed significant effects of stimulation site, stimulation intensity, and sex on CHEP parameters (N2 latency, N2P2 amplitude, and NRS). Significant positive correlations of body height with N2 latency, and pain ratings with N2P2 amplitudes were observed. This is the first time that normative values have been obtained from multiple dermatomes of the lower extremities. The present dataset will facilitate the clinical application of CHEPs in the neurophysiological diagnosis of small fiber neuropathy and by discerning pathological findings help establish a proximal-distal gradient of nerve degeneration in polyneuropathies.
A scanning microwave microscope (SMM) for spatially resolved capacitance measurements in the attofarad-to-femtofarad regime is presented. The system is based on the combination of an atomic force ...microscope (AFM) and a performance network analyzer (PNA). For the determination of absolute capacitance values from PNA reflection amplitudes, a calibration sample of conductive gold pads of various sizes on a SiO(2) staircase structure was used. The thickness of the dielectric SiO(2) staircase ranged from 10 to 200 nm. The quantitative capacitance values determined from the PNA reflection amplitude were compared to control measurements using an external capacitance bridge. Depending on the area of the gold top electrode and the SiO(2) step height, the corresponding capacitance values, as measured with the SMM, ranged from 0.1 to 22 fF at a noise level of ~2 aF and a relative accuracy of 20%. The sample capacitance could be modeled to a good degree as idealized parallel plates with the SiO(2) dielectric sandwiched in between. The cantilever/sample stray capacitance was measured by lifting the tip away from the surface. By bringing the AFM tip into direct contact with the SiO(2) staircase structure, the electrical footprint of the tip was determined, resulting in an effective tip radius of ~60 nm and a tip-sample capacitance of ~20 aF at the smallest dielectric thickness.
The spinal cord is subject to a periodic, cardiac-related movement, which is increased at the level of a cervical stenosis. Increased oscillations may exert mechanical stress on spinal cord tissue ...causing intramedullary damage. Motion analysis thus holds promise as a biomarker related to disease progression in degenerative cervical myelopathy. Our aim was characterization of the cervical spinal cord motion in patients with degenerative cervical myelopathy.
Phase-contrast MR imaging data were analyzed in 55 patients (37 men; mean age, 56.2 SD,12.0 years; 36 multisegmental stenoses) and 18 controls (9 men,
= .368; mean age, 62.2 SD, 6.5 years;
= .024). Parameters of interest included the displacement and motion pattern. Motion data were pooled on the segmental level for comparison between groups.
In patients, mean craniocaudal oscillations were increased manifold at any level of a cervical stenosis (eg, C5 displacement: controls
= 18, 0.54 SD, 0.16 mm; patients
= 29, monosegmental stenosis
= 10, 1.86 SD, 0.92 mm;
< .001) and even in segments remote from the level of the stenosis (eg, C2 displacement: controls
= 18, 0.36 SD, 0.09 mm; patients
= 52; stenosis: C3,
= 21; C4,
= 11; C5,
= 18; C6,
= 2; 0.85 SD, 0.46 mm;
< .001). Motion at C2 differed with the distance to the next stenotic segment and the number of stenotic segments. The motion pattern in most patients showed continuous spinal cord motion throughout the cardiac cycle.
Patients with degenerative cervical myelopathy show altered spinal cord motion with increased and ongoing oscillations at and also beyond the focal level of stenosis. Phase-contrast MR imaging has promise as a biomarker to reveal mechanical stress to the cord and may be applicable to predict disease progression and the impact of surgical interventions.
•The increased baseline protocol improves acquisition of contact heat evoked potentials (CHEPs) from lower extremities.•Reliability of CHEPs was better using increased baseline protocol for sacral ...and lumbar dermatomes.•Improved CHEPs acquisition may strengthen its diagnostic utility in small fiber neuropathy.
To investigate test-retest reliability of contact heat evoked potentials (CHEPs) from lower extremities using two different stimulation protocols, i.e., normal and increased baseline temperature.
A total of 32 able-bodied subjects were included and a subset (N = 22) was retested. CHEPs were recorded from three different dermatomes of the lower extremity (i.e., L2, L5, and S2). Test-retest reliability of CHEPs acquisition after simulation in various lower limb dermatomes using different stimulation protocols was analyzed.
The study revealed an improved acquisition of CHEPS employing the increased baseline protocol, particularly when stimulating more distal sites, i.e., dermatome L5 and S2. Based on repeatability coefficients, CHEP latency (N2 potential) emerged as the most robust CHEP parameter. Although CHEP amplitudes (N2P2 complex) and pain ratings were decreased in the retest, amplitudes still showed fair to excellent intraclass correlation coefficients using normal baseline or increased baseline temperature, respectively.
This is the first study to demonstrate that CHEPs acquisition from the lower extremities is improved by increasing the baseline temperature of the thermode.
This study highlights the usability of CHEPs as a viable diagnostic method to study small fiber integrity.
Increased cranio-caudal spinal cord motion is associated with clinical impairment in degenerative cervical myelopathy. However, whether spinal cord motion holds potential as a neuroimaging biomarker ...requires further validation. Different confounders (i.e. subject characteristics, methodological problems such as phase drift, etc.) on spinal cord motion readouts have to be considered. Twenty-two healthy subjects underwent phase contrast MRI, a subset of subjects (N = 9) had repeated scans. Parameters of interest included amplitude of velocity signal, maximum cranial respectively maximum caudal velocity, displacement (=area under curve of the velocity signal). The cervical spinal cord showed pulse synchronic oscillatory motions with significant differences in all readouts across cervical segments, with a maximum at C5. The Inter-rater reliability was excellent for all readouts. The test-retest reliability was excellent for all parameters at C2 to C6, but not for maximum cranial velocity at C6 and all readouts at C7. Spinal cord motion was correlated with spinal canal size, heart rate and body size. This is the first study to propose a standardized MRI measurement of spinal cord motion for further clinical implementation based on satisfactory phase drift correction and excellent reliability. Understanding the influence of confounders (e.g. structural conditions of the spine) is essential for introducing cord motion into the diagnostic work up.
Summary
Dynamic alterations in flavin adenine dinucleotide (FAD) fluorescence permit insight into energy metabolism‐dependent changes of intramitochondrial redox potential. Monitoring FAD ...fluorescence in living tissue is impeded by photobleaching, restricting the length of microfluorimetric recordings. In addition, photodecomposition of these essential electron carriers negatively interferes with energy metabolism and viability of the biological specimen. Taking advantage of pulsed LED illumination, here we determined the optimal excitation settings giving the largest fluorescence yield with the lowest photobleaching and interference with metabolism in hippocampal brain slices. The effects of FAD bleaching on energy metabolism and viability were studied by monitoring tissue pO2, field potentials and changes in extracellular potassium concentration (K+o).
Photobleaching with continuous illumination consisted of an initial exponential decrease followed by a nearly linear decay. The exponential decay was significantly decelerated with pulsed illumination. Pulse length of 5 ms was sufficient to reach a fluorescence output comparable to continuous illumination, whereas further increasing duration increased photobleaching. Similarly, photobleaching increased with shortening of the interpulse interval. Photobleaching was partially reversible indicating the existence of a transient nonfluorescent flavin derivative. Pulsed illumination decreased FAD photodecomposition, improved slice viability and reproducibility of stimulus‐induced FAD, field potential, K+o and pO2 changes as compared to continuous illumination.
Lay description
Neuronal activity is accompanied by changes in neuronal and glial energy metabolism. Redox state dependent changes in flavin adenine dinucleotide (FAD) fluorescence report on alterations of intracellular energy metabolism. However, its use in biological probes is limited by the strong photobleaching observed with fluorescence microscopy.
Here we described the dependence of FAD photobleaching on the frequency and duration of short LED pulses and compared the effects of continuous versus pulsed illumination on evoked FAD, pO2, extracellular potassium and field potential transients in hippocampal brain slices.
While continuous FAD‐excitation induced multiexponential photobleaching resulted in disturbances in energy metabolism, pulsed LED illumination yielded the same fluorescence output without affecting brain slice viability.
Abstract Objective Maternal magnesium (Mg) deficiency has been associated with fetal growth restriction. Using a mouse model of maternal Mg deficiency-induced fetal growth restriction, we sought to ...investigate the effect of Mg deficiency on placental physiology and function. Methods In vivo : Pregnant Swiss Webster mice were fed either 100% of the recommended amount of Mg (control) or 10%Mg (Mg-deficient) (8 per group). Dams were euthanized on gestational day 17 and placentas were collected, weighed and assessed for Mg concentrations, as well as nutrient transporter mRNA expression. For nutrient transfer studies, control and Mg-deficient dams (6 per group) were injected with14 C-amino acids and3 H-glucose and trans-placental passage was determined. In vitro: BeWo placental cells were grown in media containing 10%Mg to 100%Mg and the effects of Mg status on cell proliferation, oxidative stress and nutrient uptake were measured. Data were analyzed by Student's t-tests comparing controls vs. Mg-deficient animals or cells. For multiple comparisons, data were analyzed by ANOVA followed by Dunnett's post hoc testing. Results In vivo : Maternal Mg deficiency decreased placental Mg content, placental and fetal weights, ratio of fetal:placental weight (P < 0.05), placental Slc7a5 transporter mRNA expression and transplacental nutrient transport (P < 0.05). In vitro : Mg deficiency reduced BeWo nutrient uptake (P < 0.01) and cell proliferation (P < 0.01), and increased oxidative stress (P < 0.01). Conclusion These findings highlight the adverse effects of maternal Mg deficiency on fetal weight and placental function, including transport and proliferation and may explain the fetal growth restriction observed with moderate Mg deficiency in mice.
Among patients presenting with dizziness, visual dysfunction must be considered, including vertical heterophoria (VH), a frequently under-identified form of binocular vision dysfunction where there ...is vertical discrepancy between the lines of sight of the eyes when at physiologic rest. Current self-rated screening measures do not account for complex VH symptomatology including dizziness/ambulation difficulties, nausea, headache, anxiety, neck pain, and reading impairment. VH must be differentiated from vestibular/otolithic etiologies, as their treatment frequently provides inadequate relief, yet treatment of the VH can reduce/eliminate symptoms. The objective of this study is to create a valid measurement tool (binocular vision dysfunction questionnaire) to assist in identifying VH among dizzy patients to aid in appropriate referral.
Retrospective case series.
Tertiary referral center.
One hundred twenty-six patients presenting to an optometric binocular vision subspecialist diagnosed with VH.
Psychometric study. The measurement tool's internal consistency and test-retest reliability was assessed. Confirmatory and exploratory factor analyses were performed. Validity was estimated through correlations with a visual analog scale and validated instruments for headaches, dizziness, and anxiety.
Excellent reliability demonstrated including Cronbach's alpha of 0.91 and high test-retest reliability. Statistical correlations with established measurements established sound convergent/content validity. Analysis of participants who underwent treatment indicated change in BVDQ score correlates with perception of change in symptom burden.
Results suggest the BVDQ is a valid, reliable screening tool to assist otologists in identifying VH among their dizzy patients. The BVDQ may also be useful for measuring changes with various treatments, and in identifying diverse symptoms associated with BVD/VH.
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