Right Dorsolateral Prefrontal Cortex Activation during a Time Production Task: A Functional Near-Infrared Spectroscopy Study

Accurate time estimation is crucial for many human activities and necessitates the use of working memory, in which the dorsolateral prefrontal cortex (DLPFC) plays a critical role. We tested the hypothesis that the DLPFC is activated in participants attempting time estimations that require working memory. Specifically, we used functional near-infrared spectroscopy (fNIRS) to investigate prefrontal cortical activity in the brains of individuals performing a prospective time production task. We measured cerebral hemodynamic responses in 26 healthy right-handed university students while they marked the passage of specified time intervals (3, 6, 9, 12, or 15 s) or performed a button-pressing (control) task. The behavioral results indicated that participants’ time estimations were accurate with minimal variability. The fNIRS data showed that activity was significantly higher in the right DLPFC during the time estimation task compared to the control task. Theoretical considerations and the results of this study suggest that DLPFC activation resulting from time estimation indicates that the working memory system is in use.

Polymorphisms in the Sortilin-Related Receptor 1 Gene Are Associated with Cognitive Impairment in Filipinos

Background/Aims. Sortilin-related receptor 1 (SORL1) is involved in the neuronal transport processes and plays a role in the formation of amyloid plaques. This study investigated the association of 6 SORL1 single nucleotide polymorphisms (SNPs 8, 9, 10, 13, 19, and 23) with cognitive impairment (CI) in Filipinos. Methods. DNA samples from 484 subjects (100 Alzheimer’s Disease (AD) cases, 109 mild cognitive impairment (MCI) cases, 18 other types of CI, and 257 no dementia controls (NDC)) were genotyped using TaqMan SNP Genotyping Assays. Data Analysis. Our study showed strong linkage disequilibrium in the SNPs 8, 9, and 10 block. Our results showed that CI was significantly associated with SNPs 13 and 23. None of the SORL1 SNPs studied was associated with AD while SNPs 8, 9, 10, and 23 were associated with MCI. Conclusion. The findings had provided evidence that SORL1 may predispose individuals to CI. Further studies are needed to clarify the role of SORL1 in Filipinos with AD.

Clinicotherapeutic Potential of Leptin in Alzheimer’s Disease and Parkinson’s Disease

Chronic neurodegenerative diseases are a group of devastating neurological disorders that result in significant morbidity and mortality in the elderly population worldwide. Recent researches have shown some interesting associations of the classical antiobesity hormone leptin with two most important neurodegenerative diseases—Alzheimer’s disease (AD) and Parkinson’s disease (PD). Although several clinical studies have found the procognitive and memory-enhancing role of this peptide hormone in leptin-deficient patients, surprisingly it has not been used in any clinical trials involving patients with developing or full-blown neurodegenerative conditions. This review article is an attempt to bring together the existing information about the clinical associations of leptin with AD and PD. It starts with the basic understanding of leptin action in the brain and its derangements in these diseases and eventually discusses the potential of this hormone as a neuroprotective agent in clinical scenario.

Role of Interleukin-6 Correlated to C. pneumoniae Infection as a Biomarker for Prediction of Stroke Severity in Young Patients with Acute Ischemic Stroke

Background. Stroke in young is the leading cause of morbidity and mortality in the Indian subcontinent with a reported incidence of 15–30% of all stroke patients. The mechanisms for stroke in the young may include unconventional risk factors such as infections. Causative role of C. pneumoniae infection in patients with acute ischemic stroke (AIS) remains unresolved till date, although the link between C. pneumoniae and cerebrovascular disease has been investigated in many studies. This study examined the upregulation of IL-6 after acute cerebral ischemia and correlated the same with the C. pneumoniae antibody titres (IgG, IgA, and IgM). Methods. We studied blood samples from eighty (n=80) acute stroke patients and healthy age- and sex-matched controls. Venous blood samples were drawn within one week from the onset of stroke. Detection of IgA, IgG, and IgM antibodies to C. pneumoniae was done with a validated microimmunofluorescence (MIF) technique from 5 mL of serum in all subjects. Interleukin-6 was estimated with sandwich ELISA method. Results. The IL-6 levels were elevated in patients with a mean 28.9 ± 8.6 pg/mL as compared to 4.7 + 1.8 pg/mL in healthy age-matched controls (95% CI: 37.7 to 78.4; P=0.004). On correlation of IL-6 to stroke severity, it was found that 30 patients with NIHSS between 0 and 15 had mean IL-6 of 24.6 pg/mL and 50 patients had NIHSS of 18.8 (severely affected) with a mean IL-6 of 43.8 pg/mL. On multivariate analysis after adjusting for sex, hypertension, diabetes mellitus, smoking, and alcohol, the IgA seropositivity yielded an adjusted OR for stroke (4.72; 95% CI: 1.61, 13.83; P=0.005), while IgG seropositivity did not show a statistically significant result. We also observed that 81% of cases were seropositive for IgA versus 32% of controls (P=0.003) followed by IgG, as 52.7% of cases were seropositive versus 17.3% of controls (P=0.05). Multiple regression analysis was done with IL-6 as dependent variable to antibody with IL-6 as dependent variable to Cp-IgA, Cp-IgG, and IgM with 10.4% change in the IL-6 titres showing statistical significant result F(4,115) = 3.32, P=0.01. Conclusions. IL-6 has important role after acute ischemic stroke and is correlated with stroke severity and may correlate to acute or chronic infectious states with C. pneumonia.

The Effect of Sleep Deprivation on Ocular Vestibular Evoked Myogenic Potentials Using Air Conducted Sound

Vestibular evoked myogenic potential (VEMP) in response to a loud air conducted sound (ACS) recorded from extraocular muscles, the so-called ocular VEMP (oVEMP), has been confirmed to be able to evaluate utricular function. This study aimed to evaluate the effect of sleep deprivation (SD) on oVEMP parameters. oVEMPs were recorded in 20 male healthy subjects once after an ordinary sleep and once after 26–29 h of SD. The latencies of peak N1 and P1, N1-P1 amplitude, N1-P1 interval, and asymmetry ratio (AR) of oVEMP recorded from both eyes under normal sleep and SD conditions were 10.04 ± 0.59 ms versus 10.56 ± 0.69 ms (left eye), 14.95 ± 0.92 ms versus 15.64 ± 1.05 ms (left eye), and 7.44 ± 2.86 µV versus 5.26 ± 2.15 µV (left eye); 10.08 ± 0.66 ms versus 10.64 ± 0.73 ms (right eye), 14.88 ± 0.89 ms versus 15.59 ± 1.02 ms (right eye), and 7.16 ± 2.88 µV versus 5.04 ± 2.05 µV(right eye); 10.40 ± 5.81% versus 11.43 ± 6.37%, respectively. After SD, the latencies of oVEMP were delayed and N1-P1 amplitude was lower, whereas N1-P1 interval and AR remained unchanged. The present study showed that oVEMP test could be used to evaluate the fatigue induced by SD.

Impact of Obesity and Underweight on Surgical Outcome of Lumbar Disc Herniation

Background. The relationship between underweight and lumbar spine surgery is still unknown. Aim. To evaluate the effect of underweight versus obesity based on surgical outcome of lumbar disc herniation. Material and Method. In this retrospective study, we evaluated 206 patients (112 male and 94 female) with a mean age of 37.5±3.1 years old (ranged 20–72) who have been surgically treated due to the refractory simple primary L4-L5 disc herniation. We followed them up for a mean period of 42.4±7.2 months (ranged 24–57). We used Body Mass Index (BMI), Oswestry Disability Index (ODI), and Visual Analogue Scale (VAS) for categorization, disability, and pain assessment, respectively. We used Wilcoxon and Mann-Whitney U tests for statistics. Results. Surgical discectomy in all weight groups was associated with significant improvement in pain and disability, but intergroup comparison showed these improvements in both underweight and obese groups and they were significantly lower than in normal weight group. Excellent and good satisfaction rate was also somewhat lower in both these ends of weight spectrum, but statistically insignificant. Conclusion. Both obesity and underweight may have adverse prognostic influences on the surgical outcome of lumbar disc herniation, although their impact on subjective satisfaction rate seems to be insignificant.

Assessment of Nerve Injuries after Surgical Removal of Mandibular Third Molar: A Prospective Study

Although third molar extraction is a routinely carried out procedure in a dental set-up, yet it is feared both by the patient and the dentist due to an invariable set of complications associated with it, especially in the form of nerve injuries. Hence, prior to performing such procedures, it would be wise if the clinician thoroughly evaluates the case for any anticipated complications so that adequate preventive measures can be taken to minimize the traumatic outcomes of the procedure and provide maximum patient care, which would further save the clinician from any sort of litigation.

Effects of Meditation on Temporal Processing and Speech Perceptual Skills in Younger and Older Adults

The purpose of this study was to assess the temporal processing and speech perception abilities in older adults who were practicing meditation for more than five years. Participants were comprised of three groups, 30 young adults (“YA”) in the age range of 20–30 years, 30 older adults in the age range of 50–65 years who practiced meditation for a period of five years or more (effective meditators “EM”), and 51 age matched older adults who did not have any experience of meditation (non-meditators “NM”). Temporal processing was evaluated using gap detection in noise, duration discrimination, modulation detection, and backward masking and duration pattern tests. Speech perception was measured in presence of a four-talker babble at −5 dB signal to noise ratio and with the vocoded stimuli. Results revealed that EM group performed significantly better than NM group in all psychophysical and speech perception tasks except in gap detection task. In the gap detection task, two groups did not differ significantly. Furthermore, EM group showed significantly better modulation detection thresholds compared to YA. Results of the study demonstrate that the practice of meditation not only offsets the decline in temporal and speech processing abilities due to aging process but also improves the ability to perceive the modulations compared to young adults.

Molecular Diagnosis of Friedreich Ataxia Using Analysis of GAA Repeats and FXN Gene Exons in Population from Western India

The diagnosis of Friedreich ataxia is based on the clinical symptoms and GAA repeats expansions. In our experience, checking FXN gene exons for mutations along with GAA repeat analysis may give better clue for its diagnosis. In the present study, total 49 suspected Friedreich ataxia patients were analyzed for GAA repeat expansion. Eleven patients have normal number of GAA repeats, thereby termed as FRDA negative patients. Thirty-eight patients showed no amplification using GAA repeat analysis. Since no conclusion was possible based on these results, these patients were designated as uninformative. We have analyzed 5 exons of the FXN gene in FRDA negative and uninformative patients to check for possible mutations. It was observed that there were no mutations found in any of FRDA negative and most uninformative patients. We further used long range PCR to check for deletion of exon 5a. It was found that 18 patients showed expression for exon 5a PCR but none in long range PCR. Five patients showed no expression for exon 5a PCR as well as long range PCR indicating that these 5 patients may be positive FRDA patients. These findings need to be correlated with clinical history of these patients for confirmation.

Renin Angiotensin System in Cognitive Function and Dementia

Angiotensin II represents a key molecule in hypertension and cerebrovascular pathology. By promoting inflammation and oxidative stress, enhanced Ang II levels accelerate the onset and progression of cell senescence. Sustained activation of RAS promotes end-stage organ injury associated with aging and results in cognitive impairment and dementia. The discovery of the angiotensin-converting enzyme ACE2-angiotensin (1–7)-Mas receptor axis that exerts vasodilator, antiproliferative, and antifibrotic actions opposed to those of the ACE-Ang II-AT1 receptor axis has led to the hypothesis that a decrease in the expression or activity of angiotensin (1–7) renders the systems more susceptible to the pathological actions of Ang II. Given the successful demonstration of beneficial effects of increased expression of ACE2/formation of Ang1–7/Mas receptor binding and modulation of Mas expression in animal models in containing cerebrovascular pathology in hypertensive conditions and aging, one could reasonably hope for analogous effects regarding the prevention of cognitive decline by protecting against hypertension and cerebral microvascular damage. Upregulation of ACE2 and increased balance of Ang 1–7/Ang II, along with positive modulation of Ang II signaling through AT2 receptors and Ang 1–7 signaling through Mas receptors, may be an appropriate strategy for improving cognitive function and treating dementia.