Poststroke acute dysexecutive syndrome,a disorder resulting from minor stroke due to disruption of network dynamics

Stroke patients with small central nervous system infarcts often demonstrate an acute dysexecutive syndrome characterized by difficulty with attention, concentration, and processing speed, independent of lesion size or location. We use magnetoencephalography (MEG) to show that disruption of network dynamics may be responsible. Nine patients with recent minor strokes and eight age-similar controls underwent cognitive screening using the Montreal cognitive assessment (MoCA) and MEG to evaluate differences in cerebral activation patterns. During MEG, subjects participated in a visual picture–word matching task. Task complexity was increased as testing progressed. Cluster-based permutation tests determined differences in activation patterns within the visual cortex, fusiform gyrus, and lateral temporal lobe. At visit 1, MoCA scores were significantly lower for patients than controls (median [interquartile range] = 26.0 [4] versus 29.5 [3], P = 0.005), and patient reaction times were increased. The amplitude of activation was significantly lower after infarct and demonstrated a pattern of temporal dispersion independent of stroke location. Differences were prominent in the fusiform gyrus and lateral temporal lobe. The pattern suggests that distributed network dysfunction may be responsible. Additionally, controls were able to modulate their cerebral activity based on task difficulty. In contrast, stroke patients exhibited the same low-amplitude response to all stimuli. Group differences remained, to a lesser degree, 6 mo later; while MoCA scores and reaction times improved for patients. This study suggests that function is a globally distributed property beyond area-specific functionality and illustrates the need for longer-term follow-up studies to determine whether abnormal activation patterns ultimately resolve or another mechanism underlies continued recovery.

Advances in acute stroke treatment have significantly reduced motor and language deficits, converting highly morbid large hemispheric lesions into smaller infarcts with better overall long-term outcomes (1, 2). Prior work has shown that the majority of individuals presenting for follow-up 4- to 6-wk postinfarct now exhibit what would be classified as “minor symptoms,” (3) with low stroke severity measured by the NIH Stroke Scale (NIHSS) (4) and modified Rankin Scale (mRS) (5) scores. Although these individuals lack a dense hemiparesis or aphasia, over half endorse some degree of cognitive impairment that significantly impacts their recovery. Interestingly, these symptoms are typically found to be independent of stroke size, location, or coexisting depression (6, 7).Poststroke cognitive decline has a substantial presence in the literature (8–13). However, we find that rather than memory impairment or confusion, patients without prior cognitive disability report immediate difficulty with executive function, focus, concentration, and attention after a minor stroke, hereafter referred to as poststroke acute dysexecutive syndrome (PSADES) (3). Dysexecutive syndrome has been previously described in individuals with anatomic lesions (14) as well as disorders, such as schizophrenia (15) and Alzheimer’s disease (14), affecting the frontal lobes. When mild, the syndrome can be hard for others to appreciate, particularly, in previously high-functioning individuals, but poststroke, these deficits are detectable on screening tests, such as the Montreal cognitive assessment (MoCA) (16) and other scales of activities of daily living compared to age-matched controls (3). Despite the fact that following stroke, symptoms typically improve over the first 3–6 mo of recovery, PSADES impedes many successful well-educated individuals from returning to cognitively driven professions given the uncertainty of their prognosis. These decisions affect lifestyle and quality of life, resulting in lasting long-term consequences.The pathophysiology underlying PSADES is poorly understood, as many times the inciting infarct is small and does not involve an area of the brain classically thought to be important for cognitive processing. Cognitive change due to deep white matter lesions (in multiplicity) has been well described (17), but there is no clear unifying physiological explanation regarding how a single small cortical or subcortical lesion may cause significant generalized cortical dysfunction. Some posit a “network” hypothesis suggesting that an individual requires an extensive system of neuronal connectivity, involving numerous cortical and subcortical regions, in order to complete a task (18). We propose that the cognitive dysfunction of PSADES may be the result of a disruption of general network dynamics due to lesions of the subcortical white matter tracts, which would, in turn, interfere with basic network function.This study was designed as a first step in evaluating the role of network dynamics during tasks requiring attention, concentration, speed, and accuracy; all skills difficult for patients poststroke. We used magnetoencephalography (MEG) to determine the differences in cerebral activation patterns in nine individuals with small strokes versus a group of eight age-similar controls by measuring the amplitude and latency of cerebral responses during a visual comprehension task at two time points: ∼1- and 6-mo postinfarct. Our analysis focused on the early visual, M170, and M400 components of the event-related potential from the occipital lobe, fusiform gyrus, and lateral temporal lobe given their importance in visual recognition and language processing (19–22).     

Oxidative stress generated at nickel oxide nanoparticle interface results in bacterial membrane damage leading to cell death

Metal oxide nanoparticles (NPs) have shown enhanced antibacterial effects against many bacteria. Thus, understanding the potential antibacterial effects of nickel oxide nanoparticles (NiO NPs) against Gram-positive and Gram-negative pathogenic bacteria is an urgent need to enable the exploration of NiO NP use in biomedical sciences. To this end, NiO NPs were synthesized by microwave assisted hydrothermal synthesis method. The synthesized NPs were characterized by X-ray diffraction (XRD) and Fourier Transfer Infrared (FT-IR) and UV-visible spectroscopy. The morphological features of the synthesized NiO NPs were analysed using Transmission Electron Microscopy (TEM) and FE-SEM analysis. The antibacterial activity of NiO NP was explored using different antimicrobial and biophysical studies. The obtained data reveals that the NiO NP has stronger antibacterial activity against Gram-positive bacteria compared to Gram-negative bacteria. The mechanism behind the antibacterial activity of the NiO NP was explored by evaluating the amount of ROS generation at the NiO NP interface. The effect of ROS generation on the bacterial membrane was evaluated by BacLight assay and morphological analysis of the bacterial membrane using FE-SEM. The data altogether suggested that the oxidative stress generated at the NiO NP interface resulted in membrane damage leading to bacterial cell death.

Metal oxide nanoparticles (NPs) have shown enhanced antibacterial effects against many bacteria.     

Psychometric properties of a brief,clinically relevant measure of pain in patients with hepatocellular carcinoma

Purpose

Due to diagnosis at advanced stages, comorbidities, and the impact of treatment, patients with hepatocellular carcinoma (HCC) may experience pain. The purpose of this study was to evaluate the psychometric properties of a brief, clinically relevant measure of pain in HCC.

Methods

We conducted a secondary data analysis from four longitudinal studies of patients with HCC (total n = 304). All patients completed the FACT-Hepatobiliary (FACT-Hep) questionnaire, and 49 patients completed the Brief Pain Inventory (BPI) Interference scale. We conducted confirmatory factor analysis (CFA), Rasch modeling, and correlational analysis to assess the psychometrics of the three items on the FACT-Hep that assess HCC-relevant pain scale.

Results

Patients had an average age of 63.5 (±12.2) and were mostly male (76 %). The mean three-item pain subscale score was 8.5 ± 3.0. Seventy-four (24.3 %) patients reported no pain (score = 12). Results of a one-factor CFA supported unidimensionality of the items, and all items fit the Rasch model. An item-person map demonstrated that the three items covered all patients with non-extreme scores. Pain scores were significantly associated with baseline general health-related quality of life (FACT-General, r = 0.60, p < 0.001) and pain interference (BPI, r = ?0.63, p < 0.001).

Conclusions

The three FACT-Hep pain items are unidimensional, cover the range of pain experienced by most patients with HCC, and demonstrate convergent validity. This pain subscale is, if future research demonstrates its sensitivity to change, potentially useful for HCC clinical trials.     

Use of tuning fork in diagnostic auscultation of fractures

This study was conducted on 50 patients in the Central Institute of Orthopaedics, Safdarjung Hospital, New Delhi, from June to October 1985. With the help of a child's stethoscope and a tuning fork of 128 Hz, the sound conducted by an injured limb was compared with that by the uninjured limb. The presence of a fracture reduced or abolished the conduction of sound by a bone. This method allows a quick examination without causing any pain, which is an advantage in an uncooperative patient. It is also reliable in the unconscious. The test is so simple that paramedical staff can use it. The results were correct in 94 per cent of patients and were confirmed by radiological examination whereas clinical diagnosis was correct in only 88 per cent of cases.