Inverted colloidal crystal scaffolds for uniform cartilage regeneration.

A uniform distribution of chondrocytes in 3D scaffolds is a critical challenge to cartilage regeneration. This study aims to resolve the problem by showing uniformly distributed chondrogenesis in chitin/chitosan matrix with pores of inverted colloidal crystal (ICC) structure. The results revealed that the effect of solvent on the regularity of colloidal crystal arrays was in the order of ethanol > ethylene glycol > acetone. When the concentration of chitin/chitosan gel was <2.5%, the porosity of ICC scaffolds with pure ethanol was approximately 84%. The highly porous freeform scaffolds produced random and unconnected pores, in general. The viability of bovine knee chondrocytes (BKCs) in ICC constructs was >92%. Over 4 weeks of cultivation, the percentage of biodegradation of ICC scaffolds with pure ethanol was approximately 34%. The order in the produced BKCs, glycosaminoglycans (GAGs), and collagen was freeform constructs > ICC constructs with pure ethanol > ICC constructs with 95% acetone. However, the spatial distribution of BKCs in ICC constructs was more uniform than that in freeform constructs. In addition, BKCs could secrete GAGs and type II collagen in the core of ICC constructs, indicating the maintenance of phenotypic chondrocytes and their metabolism. The ICC constructs with well-controlled pore regularity and unique topography can generate uniform tissue-engineered cartilage.

Asymmetric involvement in sporadic creutzfeldt-jakob disease: clinical, brain imaging, and electroencephalographic studies.

OBJECTIVE: To ascertain the characteristics of patients with sporadic Creutzfeldt-Jakob disease (CJD) and to determine the findings of electroencephalography (EEG) and brain magnetic resonance imaging (MRI). METHODS: We pooled patients at a hospital from 2000 to 2008, and classified them according to WHO diagnostic criteria as having probable or possible CJD. We retrospectively analyzed their clinical manifestations, brain MRI, and EEG findings to evaluate correlations among them. RESULTS: In this study, 12 probable and 4 possible CJD patients were identified. Ten patients with probable CJD had asymmetric manifestations with hemiparesis, focal myoclonus, dystonia or apraxia; 9 had clinical manifestations mimicking the corticobasal syndrome. In contrast, neurological examinations did not show asymmetric signs in 4 patients with possible CJD. EEG showed a typical periodic sharp wave complex (PSWC) in 12 patients with probable CJD; most of them had bright signal intensity on diffusion-weighted imaging of the cortex and/or basal ganglia. There was a high tendency for asymmetric clinical manifestations that correlated with the presentation of PSWC and cortical lesions observed on the brain MRI scan. CONCLUSIONS: Our study indicates that asymmetric extrapyramidal symptoms/signs, in clinical features with characteristic abnormalities on MRI and EEG findings, might contribute to early diagnosis of sporadic CJD.

Detection of neuronal spikes using an adaptive threshold based on the max-min spread sorting method.

Neuronal spike information can be used to correlate neuronal activity to various stimuli, to find target neural areas for deep brain stimulation, and to decode intended motor command for brain-machine interface. Typically, spike detection is performed based on the adaptive thresholds determined by running root-mean-square (RMS) value of the signal. Yet conventional detection methods are susceptible to threshold fluctuations caused by neuronal spike intensity. In the present study we propose a novel adaptive threshold based on the max-min spread sorting method. On the basis of microelectrode recording signals and simulated signals with Gaussian noises and colored noises, the novel method had the smallest threshold variations, and similar or better spike detection performance than either the RMS-based method or other improved methods. Moreover, the detection method described in this paper uses the reduced features of raw signal to determine the threshold, thereby giving a simple data manipulation that is beneficial for reducing the computational load when dealing with very large amounts of data (as multi-electrode recordings).

Short-term thallium intoxication: dermatological findings correlated with thallium concentration.

BACKGROUND: The dermatological features and skin biopsy findings of short-term thallium intoxication have been described. However, the correlation between the dermatological findings and the thallium concentration, the prognosis of peripheral neuropathy, and a cutaneous nerve biopsy study are lacking. OBSERVATIONS: Two patients initially developed perioral numbness, erythematous facial rashes, and polyneuropathy after ingesting thallium-containing water. Severe diffuse alopecia was noted, and a skin biopsy specimen revealed parakeratosis and vacuolar degeneration of the basal layer. Examinations of the hair mount demonstrated a tapered appearance of the anagen root. A serial cutaneous nerve biopsy study showed a loss of epidermal nerves 7 weeks and even 1 year after the thallium intoxication. A toxicology survey disclosed a high concentration of thallium (about 3124 mg/L) in the water. The clinical dermatological features subsided completely, but polyneuropathy with severe painful feet persisted. The blood and daily urinary thallium concentrations decreased slowly in the following 3-month period. CONCLUSIONS: The clinical dermatological features subsided completely, but painful polyneuropathy persisted. The series cutaneous nerve biopsy specimens showed persistent damage to the sensory nerve endings. The disappearance of the dermatological features and the appearance of Mees lines correlated with the decrease of blood and urinary thallium concentrations.

Central nervous system effects in acute thallium poisoning.

We report the central nervous system manifestations, neuropsychological studies and brain magnetic resonance image (MRI) findings of two patients with acute thallium intoxication. Neurologically the patients suffered from confusion, disorientation, and hallucination in the acute stage, followed by anxiety, depression, lack of attention, and memory impairment, in addition to peripheral neuropathy. Neuropsychological tests revealed an impairment of memory function, including reversed digital span, memory registration, memory recall, memory recognition, similarity, proverb reasoning, and verbal fluency. High concentrations of thallium were found in the urine, blood, and drinking water of these two patients. Brain MRI showed lesions in the corpus striatum in one patient. During the follow-up periods, the clinical manifestations and neuropsychological studies showed a slowly progressive improvement, and a follow-up brain MRI 1.5 months later demonstrated a resolution of the lesions. We conclude that thallium intoxication might induce encephalopathy, and brain MRI studies demonstrated the acute-stage brain lesions in a severe intoxicated patient. In addition, neuropsychological tests also confirmed memory deficits, although the brain lesions in the corpus striatum might resolve.

Contact heat evoked potentials in normal subjects.

Laser-evoked potentials are widely used to investigate nociceptive pathways. The newly developed contact heat stimulator for evoking brain response has the advantages of obtaining reliable scalp potentials and absence of cutaneous lesions. This study aimed to identify the most appropriate stimulation site with consistent cortical responses, and to correlate several parameters of the contact heat evoked potentials (CHEPs) with age, gender, and body height in normal subjects. CHEPs were recorded at Cz with a contact heat stimulator (Medoc, Israel) in 35 normal controls. The subjects were asked to keep eyes open and remain alert. The baseline temperature was 32 degrees C, and stimulation peak heat intensity of 51 degrees C was applied to five body sites: bilateral forearm, right dorsum hand, right peroneal area, and right dorsum foot. Reproducible CHEPs were recorded more frequently when stimulated at volar forearm (62.5%) than at the lower limbs (around 40%). The first negative peak latency (N1) was 370.1 +/- 20.3 ms, first positive peak latency (P1) was 502.4 +/- 33.0 ms, and peak to peak amplitude was 10.2 +/- 4.9 microV with stimulation of the forearm. Perceived pain intensity was not correlated with the presence or amplitude of CHEPs. No gender or inter-side differences were observed for N1 latency and N1-P1 amplitude. Also, no correlation was noted between N1 and age or body height. These results support future clinical access of CHEPs as a diagnostic tool.

Brain connectivity of patients with Alzheimer's disease by coherence and cross mutual information of electroencephalograms during photic stimulation.

Alzheimer's disease (AD) is a neurodegenerative disease, usually diagnosed by neuropsychological tests, and excluded from other cerebral diseases by brain images. An electroencephalogram (EEG) provides a means of disclosing the reduced functional couplings between brain regions that occurs with AD. In the present study, 16 probable AD patients and 15 age-matched, gender-matched normal subjects were enrolled. Spectral coherence and cross mutual information (CMI) were used to analyze EEGs during intermittent photic stimulation (PS). Ocular- and heartbeat-related source components (SCs) obtained from multi-channel EEGs by the independent component analysis were discarded, and the photic-related SCs were reduced using a comb filter. The undisturbed SCs and photic-related SCs before and after photic reduction were used to reconstruct photic-preserved EEGs and photic-reduced EEGs, from which harmonic coherences (direct photic-driving response) and rhythmic coherences and CMI (indirect photic affection) were computed, respectively. Our results indicate that the rhythmic coherences (particularly in the alpha and beta bands) and CMI variables as well as the harmonic coherences (particularly related to 3-Hz PS) were significantly lower in the probable AD than in normal subjects, whereas the variables derived from the resting EEGs were not statistically significant. This finding implied that the variables obtained during PS could be used to disclose impaired intra-brain associations in probable AD.

Features of varicella zoster virus myelitis and dependence on immune status.

BACKGROUND: Myelitis is a rare complication of varicella zoster virus (VZV) infection and is more prevalent in immunocompromised individuals. Clinical features, outcomes, and presentations vary. The aim of the current study was to compare the clinical presentations of our patients with those reported in the literature, and to evaluate the differences in clinical features between immunocompromised and immunocompetent patients. METHODS: A review of the literature on VZV myelitis was carried out by searching PUBMED from 1980 to 2012. Clinical features of our cases and those in the literature were compared. RESULTS: There were 5 cases at our hospital and 26 were reported in the literature. Seventeen patients were immunocompromised (54.8%), and most had acquired immune deficiency syndrome (AIDS). Typical presentations (skin lesions followed by myelopathy at the corresponding level) were observed in 14 patients (45.2%). The immunocompromised patients were prone to atypical presentations (p<0.05). Outcomes were good in immunocompetent patients and relatively poor in immunocompromised patients (p<0.05). Anti-herpetic agents had no statistically significant effect on outcomes in immunocompromised patients (p=0.280), but could reduce mortality rate in AIDS patients (p<0.05). CONCLUSION: Immunocompromised individuals are susceptible to this disease, and prone to atypical presentations and poorer outcomes. Timely recognition and anti-herpes therapy may be beneficial to the outcomes. In the AIDS patients, anti-herpes therapy can reduce mortality effectively.

Partial directed coherence analysis of intracranial neural spikes in epilepsy patients.

Intracranial electroencephalograms (EEG) provide a direct observation of neural activity by placing an electrode array on the cortical surface near the suspected epileptic foci. The neural spikes appeared during inter-ictal stages are mainly produced by abnormal neural discharges from epileptic foci. The topological mapping of spikes' potentials is commonly used to identify the epileptogenic zone. However, the propagations among multi-channel spikes are also important to identify the epileptic source activity. In addition, the changes of source activities in a series of consecutive spikes reveal the time-varying neural activations during discharge process, which provide alternative information for interpreting epileptic source activity. This paper proposes a spike classification based on the similarity of phase-space features to select candidate spikes from the intracranial EEGs recorded from an 8×8 electrocorticogram grid. Then, the partial directed coherence (PDC), which can provide the flow of source activity, at each spiking time point is computed. The outflow PDCs of all electrodes are therefore displayed on the grid. Our result showed that the derived source activities in the preceding spikes had high concentrated distributions but decreased in latter spikes. This implied the epileptic discharges were initially induced by a small-area cortex neurons and then spread out.

Heparin-conjugated scaffolds with pore structure of inverted colloidal crystals for cartilage regeneration.

A uniform de novo production of neocartilage is a critical issue in the fabrication of tissue-engineered diarthrodial substitutes. The aim of this work is to develop homogeneous chondrogenesis in heparinized scaffolds with pores of inverted colloidal crystal (ICC) geometry. Monodispersed polystyrene microspheres were self-assembled by floating in the medium containing ethylene glycol, dried, annealed and infiltrated with heparin/chitin/chitosan gels. The results indicated that the colloidal template was in a structure of hexagonal arrays. In addition, the regularity of the organized pores in the scaffolds reduced when the concentration of ethylene glycol decreased. An increase in the weight percentage of heparin enhanced the viability of bovine knee chondrocytes (BKCs) in ICC matrices. Over 4 weeks of cultivation, the amount of cartilaginous components including BKCs, glycosaminoglycans (GAGs) and collagen enhanced with time. Moreover, an increase in the weight percentage of heparin promoted the production of BKCs, GAGs and collagen in ICC constructs. Histological and immunochemical staining of the cultured ICC constructs revealed minor differences in BKCs, GAGs and type II collagen between the peripheral and core regions. Therefore, the ordered pores in the heparinized ICC constructs could favor the chondrocyte culture to regenerate a uniform distribution of cartilage.

The removal of ocular artifacts from EEG signals using adaptive filters based on ocular source components.

Ocular artifacts are the most important form of interference in electroencephalogram (EEG) signals. An adaptive filter based on reference signals from an electrooculogram (EOG) can reduce ocular interference, but collecting EOG signals during a long-term EEG recording is inconvenient and uncomfortable for the patient. In contrast, blind source separation (BSS) is a method of decomposing multiple EEG channels into an equal number of source components (SCs) by independent component analysis. The ocular artifacts significantly contribute to some SCs but not others, so uncontaminated EEG signals can be obtained by discarding some or all of the affected SCs and re-mixing the remaining components. BSS can be performed without EOG data. This study presents a novel ocular-artifact removal method based on adaptive filtering using reference signals from the ocular SCs, which avoids the need for parallel EOG recordings. Based on the simulated EEG data derived from eight subjects, the new method achieved lower spectral errors and higher correlations between original uncorrupted samples and corrected samples than the adaptive filter using EOG signals and the standard BSS method, which demonstrated a better ocular-artifact reduction by the proposed method.

Complex analysis of neuronal spike trains of deep brain nuclei in patients with Parkinson's disease.

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) has been used to alleviate symptoms of Parkinson's disease. During image-guided stereotactic surgery, signals from microelectrode recordings are used to distinguish the STN from adjacent areas, particularly from the substantia nigra pars reticulata (SNr). Neuronal firing patterns based on interspike intervals (ISI) are commonly used. In the present study, arrival time-based measures, including Lempel-Ziv complexity and deviation-from-Poisson index were employed. Our results revealed significant differences in the arrival time-based measures among non-motor STN, motor STN and SNr and better discrimination than the ISI-based measures. The larger deviations from the Poisson process in the SNr implied less complex dynamics of neuronal discharges. If spike classification was not used, the arrival time-based measures still produced statistical differences among STN subdivisions and SNr, but the ISI-based measures only showed significant differences between motor and non-motor STN. Arrival time-based measures are less affected by spike misclassifications, and may be used as an adjunct for the identification of the STN during microelectrode targeting.

Significant thalamocortical coherence of sleep spindle, theta, delta, and slow oscillations in NREM sleep: recordings from the human thalamus.

The electrophysiological studies of thalamocortical oscillations were mostly done in animal models. Placement of stimulation electrodes at the anterior nucleus of the thalamus (ANT) for seizure reduction enables the study of the thalamocortical interplay in human subjects. Nocturnal sleep electroencephalograms (EEGs) and local field potentials (LFPs) of the left and right thalamus (LT, RT) were recorded in three subjects receiving ANT stimulation. Sleep stages were scored according to American Academy of Sleep Medicine criteria. The whole-night time-frequency coherence maps between EEG (C3, C4) and LFP (LT, RT) showed specific coherence patterns during non-rapid eye movement (NREM) sleep. Pooled coherence in the NREM stage was significant in slow, delta, theta and spindle frequency ranges. The spindle oscillations had the highest coherence (0.17-0.58) in the homolateral hemisphere. Together, these observations indicate that the oscillations were related to thalamocortical circuitry.

Long-term video-EEG monitoring for paroxysmal events.

BACKGROUND: Long term video-electroencephalography monitoring (VEM) has been widely used for the diagnosis, classification, and management of seizures. Few studies have systemically examined its safety issues and clinical utility. This prospective study investigates the general clinical application of long term VEM in the management of paroxysmal events. METHODS: This study cohort consisted of patients admitted to the inpatient VEM unit at Chang Gung Memorial Hospital (Lin-Kou). Standard 19 channel scalp electroencephalography (EEG), electrocardiography (ECG), and simultaneous video images were recorded continuously for 2 full days. Patient characteristics, and clinical, video-EEG and safety data were obtained and analyzed. The diagnosis and management of paroxysmal events before VEM were compared with those after VEM. RESULTS: Habitual events were recorded in 54.3% of the 129 patients, and VEM had a yield rate of 76% (events recorded or newly recorded interictal discharges) indetermining the nature of the events. Eleven patients had seizure clusters, but there was no status epilepticus or electrode-related injury. After VEM, the diagnostic categories were changed in 41.1% of the patients, and 40.3% had revisions in management. CONCLUSIONS: Long term VEM is a safe diagnostic tool providing a high diagnostic yield rate and directing adjustment of management for patients with paroxysmal events.

Periictal magnetic resonance imaging in status epilepticus.

PURPOSE: To determine the changes of magnetic resonance imaging (MRI) during the periictal phase in status epilepticus (SE). PATIENTS AND METHODS: We identified 15 patients diagnosed of status epilepticus with corresponding MRI changes, including 11 patients with generalized convulsive status epilepticus (GCSE), 2 with complex partial status epilepticus (CPSE), and 2 with simple partial status epilepticus (SPSE). All MRI changes, corresponding electroencephalogram, and prognosis were evaluated. RESULTS: Regional cortical lesions were observed on MRI, including restricted diffusion in diffusion-weighted images (DWIs) (11 out of 15) and hyperintense signal change in fluid-attenuated inversion recovery (FLAIR) images (12 out of 15) with hypervascularity and parenchymal swelling. The remote lesions included crossed cerebellar diaschisis (3 patients), ipsilateral thalamic lesion (4 patients), and basal ganglia lesions (3 patients). Although the periictal MRI changes were usually reversible, irreversible changes were also found, especially in GCSE, such as focal brain atrophy, cortical laminar necrosis, and mesial temporal sclerosis. GCSE patients with periodic epileptic form discharges had higher possibilities of widespread MRI abnormalities and poor prognosis in the future. CONCLUSIONS: In this study, DWIs and FLAIR images were proved useful in determining the extent and severity of early neuronal damage caused by epileptic discharges in SE patients. Seizure-induced long-term injuries were also observed in the follow-up MRI.

Long-term anterior thalamus stimulation for intractable epilepsy.

BACKGROUND: Deep brain stimulation (DBS) has re-emerged as an alternative therapy for intractable epilepsy. In this study, we investigated the feasibility, efficacy and safety of long-term anterior thalamic nucleus (ATN) stimulation for intractable epilepsy. METHODS: In this open-label pilot study of electrical stimulation of the ATN, we investigated four cases of intractable epilepsy (one man with generalized seizure, and three woman with partial seizure and secondary generalization; age range, 18-45 years), with a follow up of 2 years. Under the indication of bilateral or nonlocalized epileptic foci, each patient underwent stereotactic implantation of a quadripolar stimulating electrode in the bilateral ATN, guided by single-unit microelectrode recording. The stimulator was turned on after a sham period of 2-4 weeks. Seizure frequency was monitored and compared with the pre-implantation baseline. Twenty-one similar cases reported in the literature during the past 20 years were reviewed. RESULTS: Insertion into and stimulation through electrodes implanted in the ATN decreased seizure frequency, with a mean reduction rate of 49.6% in the current series. Two patients had seizure reductions of > or = 60%, with complete remission achieved in one patient. These findings were consistent with those in four other investigations of intractable epilepsy, which showed an overall rate of 45-55% in seizure reduction. One of our patients suffered a small frontal hemorrhage, and a second patient had extension erosion over the scalp; however, no resultant major or permanent neurological deficits were observed. CONCLUSIONS: Based on our study results and literature review, it appears reasonable to conclude that long-term ATN stimulation is a safe and effective treatment for seizure reduction in patients with intractable epilepsy.

Electrical stimulation of the anterior nucleus of the thalamus for intractable epilepsy: a long-term follow-up study.

PURPOSE: The anterior nucleus of the thalamus (ANT) modulates temporal lobe and hypothalamic activities, and relays information to the cingulate gyrus and entorhinal cortex. Deep brain stimulation (DBS) of the ANT has been reported to decrease seizure activity in a limited number of human subjects. However, long-term effect of chronic ANT stimulation on such patients remains unknown. We report long-term follow-up results in four patients receiving ANT stimulation for intractable epilepsy. METHODS: Four patients underwent stereotactic implantation of quadripolar stimulating electrodes in the bilateral ANT, guided by single-unit microelectrode recording. Electrode location was confirmed by postoperative magnetic resonance imaging (MRI). The stimulator was activated 2-4 weeks following electrode insertion; initial stimulation parameters were 4-5 V, 90-110 Hz, and 60-90 micros. Seizure frequency was monitored and compared with preimplantation baseline frequency. Intelligence quotient (IQ) test and auditory P300 response were performed before and after implantation of electrodes. RESULTS: Four patients (one man with generalized seizures, and three women with partial seizures and secondary generalization) aged 18-45 years old were studied with mean follow-up period of 43.8 months. The four patients demonstrated a sustained effect of 49% (range, 35-76%) seizure reduction to ANT stimulation. Simple insertion of DBS electrodes (Sham period, no stimulation) produced a mean reduction in seizures of 67% (range, 44-94%). One patient was seizure-free for 15 months with anticonvulsant medications. One patient had a small frontal hemorrhage and a second patient had extension erosion over scalp; no resultant major or permanent neurological deficit was observed. Preoperative IQ index and auditory P300 were not significantly different with those after electrodes implantation. CONCLUSIONS: Implantation of electrodes in the ANT and subsequent stimulation is associated with a significant reduction in seizure frequency. However, our study could not differentiate whether the implantation itself, the subsequent stimulation or postimplantation drug manipulation had the greatest impact. These experimental results prompt further controlled study in a large patient population.

Hereditary neuropathy with liability to pressure palsies: a clinical and genetic study of a Taiwanese family.

Hereditary neuropathy with liability to pressure palsies (HNPP), an autosomal dominant disorder, is characterized by recurrent isolated nerve palsies, which are precipitated by trivial compression or trauma. In this report, we present the clinical features, electrophysiological studies, nerve biopsy results, and molecular analyses of a Taiwanese family. Among the 7 members evaluated, one latent and three symptomatic patients were found who showed a heterogeneous presentation from asymptomatic to characteristically recurrent peripheral neuropathy. Electrophysiological studies revealed a general decrease in nerve conduction velocities in all four patients with focal conduction slowing, especially at the compression sites. A sural nerve biopsy with a teased fiber preparation in the index patient demonstrated a typical tomaculous appearance. Molecular genetic studies exhibited a deletion of the PMP22 gene in chromosome 17p11.2-12 in all 4 patients. In conclusion, the diagnosis of HNPP might be overlooked if based on clinical presentation only. Family survey and electrophysiological and genetic tests should be done to investigate this disorder.