Papers by Katarzyna Pierzchala
Metabolic Brain Disease, Aug 21, 2023
Brain edema is considered as a common feature associated with hepatic encephalopathy (HE). Howeve... more Brain edema is considered as a common feature associated with hepatic encephalopathy (HE). However, its central role as cause or consequence of HE and its implication in the development of the neurological alterations linked to HE are still under debate. It is now well accepted that type A and type C HE are biologically and clinically different, leading to different manifestations of brain edema. As a result, the findings on brain edema/swelling in type C HE are variable and sometimes controversial. In the light of the changing natural history of liver disease, better description of the clinical trajectory of cirrhosis and understanding of molecular mechanisms of HE, and the role of brain edema as a central component in the pathogenesis of HE is revisited in the current review. Furthermore, this review highlights the main techniques to measure brain edema and their advantages/disadvantages together with an in-depth description of the main ex-vivo/in-vivo findings using cell cultures, animal models and humans with HE. These findings are instrumental in elucidating the role of brain edema in HE and also in designing new multimodal studies by performing in-vivo combined with ex-vivo experiments for a better characterization of brain edema longitudinally and of its role in HE, especially in type C HE where water content changes are small.
Children affected by hepatic encephalopathy (HE) suffer from irreversible cognitive damage, and t... more Children affected by hepatic encephalopathy (HE) suffer from irreversible cognitive damage, and thus exploring the developing brain during HE is of crucial interest. Histology in an adult rat model of HE suggested alterations in the cerebellar microstructure, but there is a need for in vivo probes of these changes. Combining diffusion MRS and diffusion MRI, we measured increased metabolites’ diffusivities, as well as an increased intra-neurite/axon water diffusivity in white and gray matter in the cerebellum of a young rat model of HE compared to control rats, suggesting an alteration of cell density and/or of neurite network complexity.
Analytical Biochemistry, Oct 1, 2022
European Spine Journal, Aug 29, 2014
Introduction Symptomatic foraminal stenosis has been observed in patients with degenerative disc ... more Introduction Symptomatic foraminal stenosis has been observed in patients with degenerative disc disease, scoliosis, asymmetrical disc degeneration and spondylolisthesis. Nevertheless not all patients with the above pathologies will develop symptomatic foraminal stenosis. We hypothesised that symptomatic patients have anatomical predisposition to foraminal stenosis, namely a larger pedicle height (PH) to vertebral body height (VH) ratio, leaving less room below the pedicle for the exiting nerve root compared to asymptomatic patients. Patient sample 66 Patients were divided in two groups. The surgical group consisted of 37 patients (average age of 61 years) who presented with severe radicular symptoms resisting to conservative measures and requiring decompression and transforaminal lumbar interbody fusion (TLIF). The control group consisted of 29 patients (average age of 51 years) presenting with low back pain (LBP) but with no radicular symptoms and who were treated conservatively. Methods We measured VH at the level of the posterior wall as well as PH on parasagittal images (CT or MRI) on all lumbar levels (L1 to L5). Statistical analysis was performed using Student's t test. Results No difference in PH was found between the two groups for L1 to L4 levels. By contrast, there was a highly statistically significant difference in VH between the two groups from L1 to L4 level. In the surgical group, the VH was smaller (p \ 0.001). Conclusions Symptomatic patients with foraminal stenosis have smaller VH leading to lesser space beneath the pedicle and putting the exiting nerve root at risk in cases of spondylolisthesis or disc degeneration.
Free Radical Biology and Medicine, Mar 1, 2023
Revue de Chirurgie Orthopédique et Traumatologique, Nov 1, 2017
s des communications particulières / Revue de chirurgie orthopédique et traumatologique 103S (201... more s des communications particulières / Revue de chirurgie orthopédique et traumatologique 103S (2017) S27-S145 S71 including age, patient's size, severity according to Tonnis and hip flexion angle in the harness. Statistical analysis was undertaken. Résultats Fifty-three cases of femoral nerve palsy of various severity were identified from a group of 473 children with 527 hips treated for DDH (10%) at an average age of 3.9 months. Ninety-three percent of them presented during the first 2 weeks of treatment. FNP was more common in older and larger children with the most severe Tonnis type and a hip flexion angle in the harness above 90 degrees (P < 0.01 for all). All of them resolved spontaneously before completion of treatment without any release of the harness straps other than those required regularly in the absence of femoral nerve palsy. None of them necessitated treatment discontinuation because of FNP. We found no correlation between the presence of FNP or the time taken for spontaneous resolution and treatment failure using the harness. Discussion FNP is a fairly common complication of Pavlik harness treatment for DDH. It is most observed in higher Tonnis types, but its presence by itself is not predictive of treatment failure. The most significant risk factors for FNP seem to be DDH severity and hip flexion angle in the harness. FNP resolves spontaneously before completion of treatment without any specific measures and therefore does not require any strap release or harness discontinuation. Disclosure of interest The authors declare that they have no competing interest.
The American Journal of Gastroenterology, Sep 1, 2019
Journal of spine surgery, Mar 1, 2018
Background: To analyse the relation between immediate intraoperative neurophysiological changes d... more Background: To analyse the relation between immediate intraoperative neurophysiological changes during decompression and clinical outcome in a series of patients with lumbar spinal stenosis (LSS) undergoing surgery. Methods: Twenty-four patients with neurogenic intermittent claudication (NIC) due to LSS undergoing decompressive surgery were prospectively studied. Intra operative trans-cranial motor evoked potentials (tcMEPs) were recorded before and immediately after surgical decompression. Lower limb normalised tcMEP improvement was used as primary neurophysiological outcome. Clinical outcome was assessed using the Zurich Claudication Questionnaire (ZCQ) self-assessment score, before surgery (baseline) and at an average of 8 and 29 months post-operatively. Results: We found a moderate positive correlation between tcMEP changes and ZCQ at early followup (R=0.36). At late follow-up no correlation was found between intra-operative tcMEP and ZCQ changes. Dichotomizing the data showed a statistically significant relationship between tcMEP improvement and better functional outcome at early follow-up (P=0.013) but not at later follow-up (P=1). Conclusions: Our findings suggest that intra-operative neurophysiological improvement during decompressive surgery may predict a better clinical outcome at early follow-up although this is not applicable to late follow-up possibly due to the observed erosion of functional improvement with time.
NeuroImage, 2021
Brain glucose hypometabolism has been singled out as an important contributor and possibly main t... more Brain glucose hypometabolism has been singled out as an important contributor and possibly main trigger to Alzheimer's disease (AD). Intracerebroventricular injections of streptozotocin (icv-STZ) cause brain glucose hypometabolism without systemic diabetes. Here, a first-time longitudinal study of brain glucose metabolism, functional connectivity and white matter microstructure was performed in icv-STZ rats using PET and MRI. Histological markers of pathology were tested at an advanced stage of disease. STZ rats exhibited altered functional connectivity and intra-axonal damage and demyelination in brain regions typical of AD, in a temporal pattern of acute injury, transient recovery/compensation and chronic degeneration. In the context of sustained glucose hypometabolism, these nonmonotonic trends-also reported in behavioral studies of this animal model as well as in human AD-suggest a compensatory mechanism, possibly recruiting ketone bodies, that allows a partial and temporary repair of brain structure and function. The early acute phase could thus become a valuable therapeutic window to strengthen the recovery phase and prevent or delay chronic degeneration, to be considered both in preclinical and clinical studies of AD. In conclusion, this work reveals the consequences of brain insulin resistance on structure and function, highlights signature nonmonotonic trajectories in their evolution and proposes potent MRI-derived biomarkers translatable to human AD and diabetic populations.
Journal of Orthopaedic Surgery and Research, Nov 21, 2019
Purpose: In case of residual hip dysplasia (RHD) in children, pelvic radiographs are sometimes in... more Purpose: In case of residual hip dysplasia (RHD) in children, pelvic radiographs are sometimes insufficient to precisely evaluate the entire coverage of the femoral head, when trying to decide on the need for further reconstructive procedures. Methods: This study retrospectively compares the bony and the cartilaginous acetabular angle of Hilgenreiner (HTE) of 60 paediatric hips on pelvic MRI separated in two groups. Group 1 included 31 hips with RHD defined by a bony HTE > 20°. Group 2 included 27 hips with a HTE < 20°. They were compared by introducing a new ratio calculated from the square of cartilaginous HTE above the bony HTE on frontal MRI. The normal upper limit for this acetabular angle ratio was extrapolated from the published normal values of cartilaginous HTE and bony HTE in children. Results: The acetabular angle ratio was statistically significantly increased in the hips with RHD with a mean value of 7.1 ± 4.7 compared to the hips in the control group presenting a mean value of 2.1 ± 1.9 (p < 0.00001). Conclusions: This newly introduced ratio seems to be a helpful tool to orientate the further treatment in children presenting borderline RHD.
Journal of Hepatology, Sep 1, 2019
In hepatic encephalopathy, early neurometabolic changes occur 2-4 weeks post-bile-duct ligation. ... more In hepatic encephalopathy, early neurometabolic changes occur 2-4 weeks post-bile-duct ligation. In hepatic encephalopathy, brain glutamine increases, but creatine and ascorbate decrease. Changes in astrocyte morphology are observed 4 weeks after bile-duct ligation. Early changes in hepatic encephalopathy are suggestive of osmotic/oxidative stress. Early changes in hepatic encephalopathy are accentuated 6-8 weeks after bile-duct ligation.
Spine, Mar 15, 2018
Study design: Retrospective radiological study Objective: To evaluate the accuracy of pedicle scr... more Study design: Retrospective radiological study Objective: To evaluate the accuracy of pedicle screw insertion using O-Arm navigation, Robotic assistance or a freehand fluoroscopic technique. Summary of Background Data:Pedicle screw insertion using either 'O-Arm' navigation or robotic devices is gaining popularity. Although several studies are available evaluating each of those techniques separately, no direct comparison has been attempted. Methods: 84 patients undergoing implantation of 569 lumbar and thoracic screws were divided in three groups. Eleven patients (64 screws) had screws inserted using robotic assistance, 25 patients (191 screws) using the O-arm, while 48 patients (314 screws) had screws inserted using lateral fluoroscopy in a freehand technique. A single experienced spine surgeon assisted by a spinal fellow performed all procedures.Screw placement accuracy was assessed by two independent observers on postoperative CTs according to the A to D Rampersaud criteria. Results: No statistically significant difference was noted between the three groups. 70.4 % of screws in the freehand group, 69.6% in the O arm group and 78.8 % in the robotic group were placed completely within the pedicle margins (grade A) (p>0.05). 6.4% of screws were considered misplaced (grades C&D) in the freehand group, 4.2 % in the O-arm group and 4.7 % in the robotic group (p>0.05). The spinal fellow inserted screws with the same accuracy as the senior surgeon (p>0.05). Conclusion: The advent of new technologies does not appear to alter accuracy of screw placement in our setting. Under supervision, spinal fellows might perform equally well to experienced surgeons using new tools. The lack of difference in accuracy does not imply that the above-mentioned techniques have no added advantages.Otherissues, such as surgeon/patient radiation, fiddle factor, teaching suitability etc., outside the scope of our present study,need further assessment.
JHEP reports, Aug 1, 2022
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Free Radical Biology and Medicine, Mar 1, 2022
Computed tomography-based anatomical study. Objective. To study the secular changes in lumbar spi... more Computed tomography-based anatomical study. Objective. To study the secular changes in lumbar spinal canal dimensions. Summary of Background Data. Development of symptomatic lumbar spinal stenosis, among other factors, is related to the dimensions of the bony canal. The canal reaches its adult size early on in life. Several factors, including protein intake, may infl uence its fi nal dimensions. As with increases in human stature from improvements of socioeconomic conditions, we hypothesized that adult bony canal size has also grown larger in recent generations. Methods. This study analyzes computed tomographic reconstructions from 184 subjects performed for either trauma (n = 81) or abdominal pathologies (n = 103) and born either between 1940 and 1949 (n = 88) or 1970 and 1979 (n = 96). The cross-sectional area of the bony canal was digitally measured at the level of the pedicle (i.e ., at a level not infl uenced by degenerative changes) for each lumbar vertebra. Intra-and interobserver reliability was assessed. Results. Intra-and interobserver measurement reliability were excellent (interclass correlation coeffi cient = 0.87) and good (interclass correlation coeffi cient = 0.61), respectively. Contrary to our hypothesis, the 1940-1949 generation patient group exhibited larger lumbar canals at all levels as compared with the 1970-1979 group. Statistically this difference was highly signifi cant (P < 0.001) and particularly pronounced in the trauma subgroup.
Free Radical Biology and Medicine, 2022
The role and coexistence of oxidative stress (OS) and inflammation in type C hepatic encephalopat... more The role and coexistence of oxidative stress (OS) and inflammation in type C hepatic encephalopathy (C HE) is a subject of intense debate. Under normal conditions the physiological levels of intracellular reactive oxygen species are controlled by the counteracting antioxidant response to maintain redox homeostasis. Our previous invivo 1 H-MRS studies revealed the longitudinal impairment of the antioxidant system (ascorbate) in a bile-duct ligation (BDL) rat model of type C HE. Therefore, the aim of this work was to examine the course of central nervous system (CNS) OS and systemic OS, as well as to check for their coexistence with inflammation in the BDL rat model of type C HE. To this end, we implemented a multidisciplinary approach, including ex-vivo and in-vitro electron paramagnetic resonance spectroscopy (EPR) spin-trapping, which was combined with UV-Vis spectroscopy, and histological assessments. We hypothesized that OS and inflammation act synergistically in the pathophysiology of type C HE. Our findings point to an increased CNS-and systemic-OS and inflammation over the course of type C HE progression. In particular, an increase in the CNS OS was observed as early as 2-weeks post-BDL, while the systemic OS became significant at week 6 post-BDL. The CNS EPR measurements were further validated by a substantial accumulation of 8-Oxo-2 ′-deoxyguanosine (Oxo-8-dG), a marker of oxidative DNA/RNA modifications on immunohistochemistry (IHC). Using IHC, we also detected increased synthesis of antioxidants, glutathione peroxidase 1 (GPX-1) and superoxide dismutases (i.e.Cu/ZnSOD (SOD1) and MnSOD (SOD2)), along with proinflammatory cytokine interleukin-6 (IL-6) in the brains of BDL rats. The presence of systemic inflammation was observed already at 2-weeks post-surgery. Thus, these results suggest that CNS OS is an early event in type C HE rat model, which seems to precede systemic OS. Finally, our results suggest that the increase in CNS OS is due to enhanced formation of intra-and extra-cellular ROS rather than due to reduced antioxidant capacity, and that OS in parallel with inflammation plays a significant role in type C HE.
American Journal of Gastroenterology
Journal of Physical Chemistry C, Jan 25, 2010
An efficient, visible light active, N, S-codoped TiO 2-based photocatalyst was prepared by reacti... more An efficient, visible light active, N, S-codoped TiO 2-based photocatalyst was prepared by reacting thiourea with nanoparticulate anatase TiO 2. Commercial anatase powders were manually ground with thiourea and annealed at 400°C in two crucibles with different surface-to-volume ratios (S/V) 20 and 1.5) to prepare two N, S-codoped TiO 2 materials. The differentiated aeration conditions during the catalyst annealing on the crucibles allowed for different amounts of O 2 to reach the catalyst surface. The first material, with S/V) 20, herein referred to as D-TKP 102-A, was clear beige colored. The second material, with S/V) 1.5, herein referred to as D-TKP 102-B, was darker and revealed a markedly lower efficiency in Escherichia coli inactivation. The D-TKP 102-A powder presented visible light absorption due to the nitrogen (N) and sulfur (S) doping. X-ray photoelectron spectroscopy signals for this catalyst were observed for N 1s peaks at binding energies of 399.2 and 400.7 eV due to interstitial N-doping or Ti-ON species. The S 2p were due to SO 4-2 signals with BE >168 eV and signals at 162.8 and 167.2 eV due to anionic and cationic S-doping, respectively. By fast kinetic spectroscopy, the decay of the electron induced by pulsed light at λ) 450 nm (∼8 ns/laser pulse) was followed for the D-TKP 102-A catalyst. Undoped D-TKP 102 catalyst did not promote the electron in the visible range, and consequently no signal decay could be observed in the latter case. Low-temperature electron spin resonance measurements at 8 K provided evidence for electrons trapped in shallow traps, such as oxygen vacancies, V o , induced by N, S doped on D-TKP 102-A. The ESR measurements implementing the reactive scavenging with singlet oxygen scavenger, TMP-OH, revealed the production of singlet oxygen (1 O 2).
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Papers by Katarzyna Pierzchala