Degenerative cervical myelopathy (DCM) is a severe consequence of degenerative cervical spinal cord (CSC) compression. The non-myelopathic stage of compression (NMDC) is highly prevalent and often progresses to disabling DCM. This study aims to disclose markers of progressive neurochemical alterations in NMDC and DCM by utilizing an approach based on state-of-the-art proton magnetic resonance spectroscopy (1H-MRS). Proton-MRS data were prospectively acquired from 73 participants with CSC compression and 47 healthy controls (HCs). The MRS voxel was centered at the C2 level. Compression-affected participants were clinically categorized as NMDC and DCM, radiologically as mild (MC) or severe (SC) compression. CSC volumes and neurochemical concentrations were compared between cohorts (HC vs. NMDC vs. DCM and HC vs. MC vs. SC) with general linear models adjusted for age and height (pFWE < 0.05) and correlated to stenosis severity, electrophysiology, and myelopathy symptoms (p < 0.05). Whereas the ratio of total creatine (tCr) to total N-acetylaspartate (tNAA) increased in NMDC (+11%) and in DCM (+26%) and SC (+21%), myo-inositol/tNAA, glutamate + glutamine/tNAA, and volumes changed only in DCM (+20%, +73%, and -14%) and SC (+12%, +46%, and -8%, respectively) relative to HCs. Both tCr/tNAA and myo-inositol/tNAA correlated with compression severity and volume (-0.376 < r < -0.259). Myo-inositol/tNAA correlated with myelopathy symptoms (r = -0.670), whereas CSC volume did not. Short-echo 1H-MRS provided neurochemical signatures of CSC impairment that reflected compression severity and clinical significance. Whereas volumetry only reflected clinically manifest myelopathy (DCM), MRS detected neurochemical changes already before the onset of myelopathy symptoms.
- MeSH
- Adult MeSH
- Inositol metabolism MeSH
- Spinal Cord Compression metabolism pathology MeSH
- Cervical Cord * MeSH
- Cervical Vertebrae MeSH
- Creatine metabolism MeSH
- Aspartic Acid analogs & derivatives metabolism MeSH
- Glutamic Acid metabolism MeSH
- Middle Aged MeSH
- Humans MeSH
- Magnetic Resonance Spectroscopy * MeSH
- Aged MeSH
- Sensitivity and Specificity MeSH
- Case-Control Studies MeSH
- Severity of Illness Index MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Aged MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, N.I.H., Extramural MeSH
The effect of gradient steepness on the kinetic performance limits and peak compression effects has been assessed in gradient mode for the separation of phenol derivatives using columns packed with 2.6μm core-shell particles. The effect of mobile-phase velocity on peak capacity was measured on a column with fixed length while maintaining the retention factor at the moment of elution and the peak-compression factor constant. Next, the performance limits were determined at the maximum system pressure of 100MPa while varying the gradient steepness. For the separation of small molecules applying a linear gradient with a broad span, the best performance limits in terms of peak capacity and analysis time were obtained applying a gradient-time-to-column-dead-time (tG/t0) ratio of 12. The magnitude of the peak-compression factor was assessed by comparing the isocratic performance with that in gradient mode applying different gradient times. Therefore, the retention factors for different analytes were determined in gradient mode and the mobile-phase composition in isocratic mode was tuned such that the difference in retention factor was smaller than 2%. Peak-compression factors were quantitatively determined between 0.95 and 0.65 depending on gradient steepness and the gradient retention factor.
Otoky dolních končetin mohou být projevem mnoha patofyziologických stavů, na jejichž rozvoji se podílí celá řada faktorů, které ovlivňují hemodynamickou situaci mezi vaskulárním řečištěm a intersticiem. Jsou častým problémem, se kterým pacienti přicházejí k lékaři. Chronické otoky dolních končetin mohou souviset s celkovými onemocněními nebo mohou mít příčinu lokální, omezenou pouze na dolní končetiny. K nejčastějším chronickým otokům dolních končetin, z hlediska dermatologa, náleží flebedém, lymfedém a lipedém. Vzhledem k tomu, že se jedná o otoky chronické, většinou progredující, bývají spojeny s řadou komplikací, s nepříjemnými subjektivními pocity, mnohdy s trvalými následky, které výrazně snižují kvalitu života postiženého jedince.
Lower limb edema can be a manifestation of many pathophysiological conditions in the development of which a number of factors are involved that affect the pressure balance between the vascular bed and the interstitium. It is a common complaint of patients for which they see a physician. Chronic lower limb edema may be associated with systemic disease or may have a local cause, confined only to the lower limbs. From a dermatologist’s viewpoint, chronic lower limb edema is most commonly represented by hyperosmolar edema: phlebedema, lymphedema, and lipedema. Given the fact that this type of edema is chronic and mostly progressive, it tends to be associated with a number of complications, subjective feelings of discomfort, and often permanent sequelae that significantly reduce the quality of life of the person affected.
- Keywords
- flebedém,
- MeSH
- Varicose Ulcer physiopathology MeSH
- Lower Extremity blood supply pathology MeSH
- Edema etiology complications blood physiopathology MeSH
- Drug Therapy MeSH
- Infections MeSH
- Compression Bandages utilization MeSH
- Humans MeSH
- Lipedema MeSH
- Scleroderma, Localized MeSH
- Lymphedema * diagnosis etiology classification MeSH
- Rehabilitation MeSH
- Severity of Illness Index MeSH
- Venous Insufficiency complications MeSH
- Check Tag
- Humans MeSH
- Publication type
- Review MeSH
OBJECTIVE: Translation of the contact zone in articulating joints is an important component of joint kinematics, yet rarely investigated in a biological context. This study was designed to investigate how sliding contact areas affect cartilage mechanobiology. We hypothesized that higher sliding speeds would lead to increased extracellular matrix mechanical stress and the expression of catabolic genes. DESIGN: A cylindrical Teflon indenter was used to apply 50 or 100 N normal forces at 10, 40, or 70 mm/s sliding speed. Mechanical parameters were correlated with gene expressions using a multiple linear regression model. RESULTS: In both loading groups there was no significant effect of sliding speed on any of the mechanical parameters (strain, stress, modulus, tangential force). However, an increase in vertical force (from 50 to 100 N) led to a significant increase in extracellular matrix strain and stress. For 100 N, significant correlations between gene expression and mechanical parameters were found for TIMP-3 (r(2) = 0.89), ADAMTS-5 (r(2) = 0.73), and lubricin (r(2) = 0.73). CONCLUSIONS: The sliding speeds applied do not have an effect on the mechanical response of the cartilage, this could be explained by a partial attainment of the "elastic limit" at and above a sliding speed of 10 mm/s. Nevertheless, we still found a relationship between sliding speed and gene expression when the tissue was loaded with 100 N normal force. Thus despite the absence of speed-dependent mechanical changes (strain, stress, modulus, tangential force), the sliding speed had an influence on gene expression.
- Publication type
- Journal Article MeSH
Záměrem tohoto článku je poskytnout analýzu ze systému vycházejících metod, které se používají k hodnocení exkavace terče zrakového nervu, určit možné nedostatky /chyby těchto způsobů, a navrhnout alternativy, jak lépe odhadnout tuto anatomickou veličinu. Odhad velikosti exkavace zrakového nervu vyžaduje analytické porozumění jak psychofyzikálnímu, tak i matematickému základu, z nějž vychází toto měření. Je-li (desetinný) poměr terče k exkavaci (C/D, cup-to-disc ratio) použit k hodnocení exkavace terče zrakového nervu, je vytvořen jednorozměrný, lineární odhad, který je postupně určen buďto z dvou- nebo trojrozměrného, nelineárního měření plochy nebo objemu. Když, vzhledem k psychofyzikálním omezením, která limitují tento úkol, odhadujeme z velikosti objemu na velikost plochy a z ní na lineární měření, pak takovýto, z údajů komprimovaný odhad exkavace zrakového nervu nemůže ani přesně odpovídat, ani správně vyjadřovat skutečnou míru exkavace právě se vyskytující na terči zrakového nervu. Tento typ jednorozměrného měření (když porovnáváme výpočet z dvou- nebo trojrozměrného měření rozsahu exkavace zrakového nervu), zdá se, způsobuje chybu, která, protože je nejvíce vyjádřena z počátku rozvoje onemocnění, často nadhodnocuje rozsah relativní exkavace (procento exkavace), který je přítomen v patologickém procesu, jako je glaukom. Tatáž systémová chyba může také vést k nadhodnocení rozvoje exkavace, zejména u zrakových nervů s nízkou hodnotou poměru exkavace k terči (C/D poměr). Aby mohl být proveden klinicky smysluplný odhad exkavace terče zrakového nervu, praktický lékař si potřebuje být vědom psychofyzikálních a matematických omezení, která jsou podstatná při lineárním odhadu velikosti poměru exkavace k terči (C/D poměr) pozorované na fyzické struktuře jako je zrakový nerv. Výsledné chyby převodu, zapříčiněné pozorovatelem, který extrapoluje ze tří- na dvoj- a pak na jednorozměrnou veličinu (objem, plocha, úsečka) a z nelineárních na lineární veličiny a chyby, které jsou zapříčiněné optickými klamy, způsobené faktory jako je topologie terče, jeho morfologie a ametropie - to vše může ovlivnit subjektivně podložené odhady velikosti exkavace terče. Aby se mohly zlepšit klinické výsledky, je k diskusi navrhována nelineární matematická metoda, která využívá dvoj- nebo trojrozměrných objektivních měření exkavace terče zrakového nervu k přesnějšímu a pečlivějšímu popsání anatomické veličiny (terč, exkavace a lem). Autoři přiznávají, že jakákoliv navrhovaná metoda je pouze počátkem práce, které je potřeba ke zlepšení klinických hodnot tohoto typu měření.
The intent of this paper is to provide a systems-based analysis of the methods used to evaluate optic nerve cupping, identify potential flaws in these systems, and propose alternatives better to assess this anatomic quantity. Estimation of optic nerve cupping requires an analytic understanding of both the psychophysical as well as the mathematical bases inherent in this measure. When the (decimal-based) cup-to-disc ratio is used to quantitate optic nerve cupping, a one-dimensional, linear estimate is produced, which in turn is derived from two- or three-dimensional, non-linear physical quantities of area or volume, respectively. When extrapolating from volume, to area, to linear measures, due to the psychophysical constraints which limit this task, such a data-compressed estimate of optic nerve cupping may neither accurately reflect, nor correctly represent, the true amount of cupping actually present in the optic nerve head. This type of one-dimensional metric (when comparing calculations from two- or three-dimensional measures over a range of optic nerve cupping), appears to introduce errors which, while most pronounced earlier on in the disease progression, often overestimate the amount of relative cupping (percent cupping) present in a pathological process like glaucoma. The same systemic errors can also lead to overestimation of the progression in cupping, especially in optic nerves with low cup-to disc values. To provide clinically meaningful estimates of optic nerve cupping, the practitioner needs to be aware of psychophysical and mathematical limitations inherent in using a linear cup-to-disc ratio to estimate the amount of cupping observed in a physical structure like the optic disc. The resultant flaws introduced by observer extrapolation from three, to two, to one dimensions (volume, area, and linear); transposition from non-linear to linear quantities; and optical illusions, caused by factors like disc topology, morphology, and ametropia, can all influence subjective-based estimates of optic nerve cupping. To improve clinical outcomes, a non-linear mathematical technique is proposed which utilizes two- or three-dimensional objective measures of optic nerve cupping to describe, more accurately and more precisely, the anatomic quantities (disc, cup, and rim) under discussion. The authors acknowledge that any proposed technique is only a beginning to the work required to improve the clinical value of this type of measure.
- Keywords
- objem, optické klamy, lineární měření, plocha, cup-to-disc ratio,
- MeSH
- Anthropometry MeSH
- Diagnostic Techniques, Ophthalmological * MeSH
- Optic Disk * anatomy & histology physiopathology MeSH
- Glaucoma * diagnosis MeSH
- Humans MeSH
- Linear Models MeSH
- Nonlinear Dynamics MeSH
- Observer Variation MeSH
- Size Perception MeSH
- Refractive Errors complications MeSH
- Reproducibility of Results MeSH
- Models, Theoretical * MeSH
- Visual Perception MeSH
- Optical Illusions physiology MeSH
- Check Tag
- Humans MeSH
Cíl: Cílem práce bylo pilotní prospektivní vyhodnocení kapilaroskopických nálezů u pacientů s Raynaudovým fenoménem a jejich případného vztahu se základními imunologickými parametry. Metodika: V roce 2010 bylo vyšetřeno 51 pacientů (37 žen, 14 mužů) s poruchami periferního prokrvení typu Raynaudova fenoménu s trváním projevů onemocnění ≤ 48 měsíců. Pacienti měli vedle standardních cévních vyšetřeních provedenu kapilaroskopii na přístroji Leica S6D. Kapilaroskopické nálezy byly rozděleny do tří stupňů (bez postižení až výrazně patologický nález). Po cévním a kapilaroskopickém vyšetření následovalo vyšetření na přítomnost autoprotilátek. Výsledky: Metodou lineární regrese byl nalezen vztah mezi zhoršujícími se kapilaroskopickými nálezy a zvyšující se pravděpodobností výskytu autoprotilátek (p = 0,023). Vztah k typům protilátek prokázán nebyl. Nebyl prokázán ani vztah mezi kapilaroskopickými nálezy a věkem pacientů a délkou trvání Raynaudova fenoménu. Závěr: V pilotním souboru pacientů se prokázal vztah mezi kapilaroskopickými nálezy a pravděpodobností výskytu autoprotilátek u pacientů s Raynaudovým fenomeném. Kapilaroskopické vyšetření je vhodnou metodou pro vyšetření pacientů s vasoneurózami a může sloužit k vytypovávání pacientů pro vyšetření autoprotilátek.
Aim: The aim of this study was to obtain a pilot prospective evaluation of capillaroscopic fi ndings in patients with Raynaud's phenomenon and of their putative association with basic immunological parameters. Methods: Fifty-one patients (37 females, 14 males) with peripheral blood supply disorders corresponding to the Raynaud's phenomenon and with disease manifestations lasting up to 48 months were examined in 2010. Besides standard vascular examination, the patients also underwent capillaroscopy using Leica S6D device. Three stages of capillaroscopic fi ndings were defi ned, from normal to marked pathology. Vascular and capillaroscopic examinations were followed by autoantibody assays. Results: Using linear regression analysis, we demonstrated a positive association between the stage of capillaroscopic fi ndings and the probability of autoantibody presence (p = 0.023). No association with the type of autoantibodies was documented. We were also not able to demonstrate an association between capillaroscopic fi ndings, age of the patients and duration of the Raynaud's phenomenon. Conclusion: An association between capillaroscopic fi ndings and the probability of autoantibody presence was shown in a pilot population of patients with Raynaud's phenomenon. Capillaroscopy is suitable for patients with vascular neuroses and can be helpful when deciding which patients should undergo autoantibody testing.
- Keywords
- vasoneuróza,
- MeSH
- Autoantibodies analysis immunology MeSH
- Financing, Organized MeSH
- Capillaries pathology MeSH
- Humans MeSH
- Microscopic Angioscopy methods utilization MeSH
- Pilot Projects MeSH
- Raynaud Disease diagnosis immunology MeSH
- Regional Blood Flow MeSH
- Nerve Compression Syndromes diagnosis immunology MeSH
- Check Tag
- Humans MeSH
PURPOSE: Vertically unstable sacral transforaminal fractures can be stabilized with a transiliac internal fixator (TIFI) or two iliosacral screws (IS). This study was designed to compare stiffness between TIFI and IS. METHODS: Using CT images finite element model of the pelvis was developed. Denis II type fracture was simulated and fixed either with TIFI or two IS. The sacral base was loaded vertically (250-500 N), displacement magnitudes on medial and lateral fracture surface and the maximum bone stress were calculated. The intact pelvis was used as a reference. Stiffness was determined by linear regression of load and displacement, computed stiffness ratio %. The von Mises stress was expressed as % ratio, evaluation of colour mapping was made. RESULTS: The mean stiffness ratio medially in TIFI was 75.22%, in IS 46.54% (p = 0.00005), laterally in TIFI 57.88%, in IS 44.74% ( p = 0.03996). The von Mises stress ratio of TIFI was 139.27%, of IS 565.35% ( p < 0.00001). CONCLUSIONS: Significantly higher stiffness and lower stress were found in TIFI model. TIFI provides a lower risk of over-compression of the fracture line in comparison with IS. TIFI thus exhibits superiority for fixation of trans- foraminal fractures, particularly with comminutive zone.
- MeSH
- Finite Element Analysis MeSH
- Biomechanical Phenomena MeSH
- Accidents, Traffic MeSH
- Fractures, Bone surgery MeSH
- Spinal Fractures surgery MeSH
- Internal Fixators * MeSH
- Bone Screws * MeSH
- Sacrum surgery MeSH
- Humans MeSH
- Linear Models MeSH
- Ilium surgery MeSH
- Compressive Strength MeSH
- Tomography, X-Ray Computed MeSH
- Regression Analysis MeSH
- Models, Statistical MeSH
- Materials Testing MeSH
- Fracture Fixation, Internal instrumentation methods MeSH
- Imaging, Three-Dimensional MeSH
- Check Tag
- Humans MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Comparative Study MeSH
This paper evaluates and compares the properties of directly compressible tabletting materials and matrix tablets containing a combination of α-lactose monohydrate and microcrystalline cellulose in the 3:1 ratio in a physical mixture and in a coprocessed dry binder. Tested parameters include flow properties, compressibility, compactibility and the rate of drug release from tablets. Compressibility is evaluated by means of the energy profile of the compression process. Compactibility is evaluated by means of the tensile strength of the tablets. Dissolution testing is done using the rotating basket method. Dissolution profiles are evaluated by non-linear regression analysis. Total energy of compression and plasticity values were higher in tabletting materials with the coprocessed dry binder. Increasing additions of polyvinyl alcohol decreased the values of total energy of compression, plasticity, tensile strength of tablets and drug release rate. Dissolution behaviour of tablets, which contained the physical mixture or coprocessed dry binder and the same amount of polyvinyl alcohol, was comparable.
- MeSH
- Cellulose chemistry MeSH
- Chemistry, Pharmaceutical methods MeSH
- Technology, Pharmaceutical methods MeSH
- Salicylic Acid administration & dosage chemistry MeSH
- Lactose chemistry MeSH
- Nonlinear Dynamics MeSH
- Tensile Strength MeSH
- Polyvinyl Alcohol chemistry MeSH
- Excipients chemistry MeSH
- Solubility MeSH
- Tablets MeSH
- Drug Liberation MeSH
- Publication type
- Journal Article MeSH
- Comparative Study MeSH
- MeSH
- Pain radiotherapy MeSH
- Dose Fractionation, Radiation MeSH
- Combined Modality Therapy MeSH
- Spinal Cord Compression complications radiotherapy MeSH
- Radiotherapy, Conformal methods MeSH
- Bone Density drug effects radiation effects MeSH
- Humans MeSH
- Neoplasm Metastasis * radiotherapy MeSH
- Bone Neoplasms radiotherapy secondary MeSH
- Brain Neoplasms radiotherapy secondary MeSH
- Spinal Neoplasms radiotherapy secondary MeSH
- Breast Neoplasms * complications MeSH
- Palliative Care * methods MeSH
- Spine radiation effects MeSH
- Radiosurgery MeSH
- Radiotherapy methods MeSH
- Stereotaxic Techniques MeSH
- Check Tag
- Humans MeSH
- Female MeSH
- Publication type
- Research Support, Non-U.S. Gov't MeSH
