Clinical applications of platelet-rich plasma in patellar tendinopathy.

Platelet-rich plasma (PRP), a blood derivative with high concentrations of platelets, has been found to have high levels of autologous growth factors (GFs), such as transforming growth factor-ß (TGF-ß), platelet-derived growth factor (PDGF), fibroblastic growth factor (FGF), vascular endothelial growth factor (VEGF), and epidermal growth factor (EGF). These GFs and other biological active proteins of PRP can promote tissue healing through the regulation of fibrosis and angiogenesis. Moreover, PRP is considered to be safe due to its autologous nature and long-term usage without any reported major complications. Therefore, PRP therapy could be an option in treating overused tendon damage such as chronic tendinopathy. Here, we present a systematic review highlighting the clinical effectiveness of PRP injection therapy in patellar tendinopathy, which is a major cause of athletes to retire from their respective careers.

Markov analysis of sleep dynamics.

A new approach, based on a Markov transition matrix, is proposed to explain frequent sleep and wake transitions during sleep. The matrix is determined by analyzing hypnograms of 113 obstructive sleep apnea patients. Our approach shows that the statistics of sleep can be constructed via a single Markov process and that durations of all states have modified exponential distributions, in contrast to recent reports of a scale-free form for the wake stage and an exponential form for the sleep stage. Hypnograms of the same subjects, but treated with Continuous Positive Airway Pressure, are analyzed and compared quantitatively with the pretreatment ones, suggesting potential clinical applications.

Gray matter deficits in young adults with narcolepsy.

OBJECTIVES: The aim of this study was to investigate gray matter volume changes in narcolepsy. MATERIALS AND METHODS: An optimized voxel-based morphometry was conducted for 17 young adults with a sole diagnosis of human leukocyte antigen DQB(1) 0602 positive narcolepsy with cataplexy (26.6 +/- 5.2 years old) and 17 comparison subjects (24.6 +/- 4.9 years old) using 3 Tesla scanner. Gray matter volumes in the bilateral hypothalamic voxel of interests (VOI) were also calculated. RESULTS: Compared with the comparison subjects, narcoleptic patients had gray matter volume decrease in the right hypothalamus and other regions including subcortical, prefrontal, limbic and occipital areas. Narcoleptic patients also had lower gray matter volume on predefined VOI at the bilateral hypothalamus, which correlated with the Ullanlinna Narcolepsy Scale score. CONCLUSIONS: Current findings suggest that narcoleptic patients have structural abnormalities in hypothalamus, which might be related to the clinical manifestation of narcolepsy with cataplexy.

Automatic ballistocardiogram (BCG) beat detection using a template matching approach.

This paper suggests a beat detection method for ballistocardiogram (BCG) from an unconstrained cardiac signal monitoring devices. A fiducial peak point of BCG is an I-J-K complex which corresponds with ventricle contraction and Electrocardiogram (ECG) QRS complex. The goal of the method is extraction of J peak without ECG synchronization. The detection method is based on a "template matching" rule evaluated using a correlation function in a local moving-window procedure. The total beat detection algorithm operates in two stages, template definition stage and beat detection stage with defined template in previous stage. In the first stage, the BCG template is constructed by the expert with an empirical analysis of BCG signal and measurement device. In the second stage, the correlation function calculates an accuracy of template with BCG signal using a local moving-window. The data analysis has been performed on the subjects tested at Seoul National University Hospital Sleep Medicine Center and presents 95.16% of sensitivity and 94.76% of positive predictivity value for the J peak detection.

Computerized assessment of cognitive impairment in narcoleptic patients.

OBJECTIVES - This study was aimed to investigate the comprehensive range of cognitive performance using the objective computerized assessment system in narcolepsy and age, gender, and IQ-matched healthy comparison. MATERIALS AND METHODS - The cognitive functions of 24 patients with narcolepsy and 24 healthy comparison subjects were assessed. RESULTS - Narcoleptics performed more frequent omission and commission errors in the vigilance test, and more frequent omission errors in the continuous performance test. Narcoleptics' response time was slower than healthy volunteers, and the differences were more exaggerated in more complex tasks. The simple repetitious working performance was more impaired in the narcoleptic subjects than in healthy comparison subjects. Narcolepsy group showed worse performances in the determination unit than the comparison group, and this impairment became more salient in faster stimuli relative to slower ones. CONCLUSIONS - Narcoleptics have deficits of efficiency in attention allocation and execution as well as simple vigilance problem.

Decreased cerebral blood flow of thalamus in PTSD patients as a strategy to reduce re-experience symptoms.

OBJECTIVE: To investigate alterations of regional cerebral blood flow (rCBF) in subjects with post-traumatic stress disorder (PTSD). METHOD: Using [99Tcm]-hexamethyl propylenamino oxime single photon emission computed tomography, the rCBF under resting condition was compared between 19 survivors of the Taegu subway fire with PTSD and 19 comparison subjects. RESULTS: PTSD patients showed a decreased rCBF in the right thalamus and an increased rCBF in the right superior parietal lobe relative to comparison subjects (corrected P < 0.05). The rCBF in the right thalamus positively correlated with the severity of current re-experience symptoms in PTSD subjects. CONCLUSION: Our finding of the thalamic rCBF decrease in PTSD patients may be a strategy to reduce re-experience symptom, by evading the process of external and internal information which can evoke traumatic memory. In addition, the parietal rCBF increase in our PTSD patients might be related to altered information processing in PTSD.

Degree of arousal is most correlated with blood pressure reactivity during sleep in obstructive sleep apnea.

We investigated blood pressure (BP) reactivity of obstructive sleep apnea (OSA) during rapid eye movement (REM) sleep and non-rapid eye movement (NREM) sleep. The influences on BP reactivity of degree of arousal, the lowest O2 saturation (SaO2), and respiratory disturbance (RD) duration were compared. Ten normotensive or borderline hypertensive patients with OSA were studied with one-night polysomnography including non-invasive beat-to-beat BP monitoring (Finapres). We compared baseline BP, pre-apneic BP, and post-apneic BP during both REM and NREM sleep. Also, relationships between delta BP (post-apneic BP minus pre-apneic BP) and degree of arousal, the lowest SaO2, and RD duration were examined. During both REM and NREM sleep, pre-apneic BP was elevated compared with baseline BP. Post-apneic BP elevation was noted compared with pre-apneic BP. The degree of arousal was more significantly correlated with delta BP than the lowest SaO2. RD duration was hardly correlated with delta BP. Pre-apneic BP elevation seems to result from cumulation of sympathetic activation and sympathetic nervous system resetting. The correlation between delta BP and degree of arousal suggests that sympathetic activation causing post-apneic BP elevation may result mainly from an arousal response regardless of hypoxia.

Automated sleep stage scoring using hybrid rule- and case-based reasoning.

We propose an automated method for sleep stage scoring using hybrid rule- and case-based reasoning. The system first performs rule-based sleep stage scoring, according to the Rechtschaffen and Kale's sleep-scoring rule (1968), and then supplements the scoring with case-based reasoning. This method comprises signal processing unit, rule-based scoring unit, and case-based scoring unit. We applied this methodology to three recordings of normal sleep and three recordings of obstructive sleep apnea (OSA). Average agreement rate in normal recordings was 87.5% and case-based scoring enhanced the agreement rate by 5.6%. This architecture showed several advantages over the other analytical approaches in sleep scoring: high performance on sleep disordered recordings, the explanation facility, and the learning ability. The results suggest that combination of rule-based reasoning and case-based reasoning is promising for an automated sleep scoring and it is also considered to be a good model of the cognitive scoring process.

Transdermal scopolamine alters phasic REM activity in normal young adults.

Transdermal scopolamine has been widely used for the prevention of motion-sickness by travelers due to its potent anticholinergic effects and the ease of administration. Nevertheless, its effects on sleep physiology are not known, despite the wellknown fact that the administration of scopolamine as an injection or an oral form could influence the sleep architecture, especially prolonging rapid eye movement (REM) sleep latency and shortening duration of REM sleep. This study aimed to measure the influence of transdermal scopolamine on REM sleep in order to examine whether it affects REM sleep as in the previous studies. We studied eight young healthy male adults polysomnographically for three nights including one adaptation night in a double blind crossover design and compared REM sleep-related variables between sleeps with and without scopolamine patch of 1.5 mg. We found no differences in tonic REM sleep measures such as REM duration and REM latency, but phasic REM sleep measures such as total REM activity (p < 0.05) and total REM density (p < 0.05) were significantly suppressed by the transdermal scopolamine; REM densities of the first (p < 0.05) and the second (p < 0.05) REM sleep periods as well as REM activity of the fourth REM sleep period (p < 0.05) were decreased significantly on the scopolamine patch nights compared with placebo patch nights. These results suggest that phasic REM components reflect cholinergic mechanism in the central nervous system (CNS) even at the lowest commercial dose, and could be useful markers of CNS cholinergic activities in the future research.

Sleep in Korea: a developmental perspective.

Sleep is an ubiquitous phenomenon. It is a developmental product, being subjected to the vicissitudes of human behavior and culture. The author will attempt to elaborate on sleep, sleep disorders, and sleep medicine in Korea from various developmental perspectives (i.e. personal, national and scientific). Korea is a rapidly developing industrialized nation and is now experiencing immense cultural changes which force individuals to change their behavior and value systems. For example, shift working is becoming increasingly popular and early working hours are being adopted by more companies as a measure to win competitions in the international market. In the clinical setting it is observed very easily that patients develop and maintain disturbed sleep-wake rhythm and its consequences. More obstructive sleep apnea, presumably due to obesity, are observed and studied in sleep clinics. The nuclear family system, an inevitable outcome of industrialization, produces some profound difference in sleeping arrangement such as children's earlier separation from parental or grandparental sleeping environment. The question is how these and other industrialization-related changes may affect the incidence and the manifestation of sleep and sleep disorders. In the background there is emerging interest in healthy sleep and sleep disorders, exemplified by increasing coverage of the topics in the mass media and the publication business. Development of sleep medicine/research per se also involves a developmental perspective. Interests in sleep and sleep disorders began sporadically decades ago in Korea and are now actively being organized mainly by the Korean Association of Sleep Medicine and Psychophysiology as a unified developing force. Understanding of sleep and of sleep disorders is not complete without in-depth understanding of culture, philosophy, and tradition from developmental perspectives. Traditional ideas and wisdom from the past are the unavoidable resources for further understanding sleep and developing sleep researches/medicine in Korea as well as in Asia.

Maintenance of wakefulness test in obstructive sleep apnea syndrome.

The usefulness of a 40-min per trial version of the maintenance of wakefulness test was assessed in 322 patients with obstructive sleep apnea. This test is a variant of the multiple sleep latency test in which patients are asked to remain awake in a quiet darkened room, and then monitored for electroencephalographic sleep onset. The four trials of the test are each stopped after 40 min. The mean sleep latency for all patients was 26.0 +/- 11.8 (SD) min. In a group of 24 patients who underwent treatment with nasal continuous positive airway pressure, the mean sleep latency increased from 18.0 +/- 12.3 to 31.9 +/- 10.4. The strongest nocturnal correlates of the MWT sleep latency were respiratory arousal index (r = -.35), mean oxygen saturation (r = .30), and weight/height ratio (r = -.25). These correlations were comparable to other studies using the MSLT. There were strong intercorrelations among the variables. In the more severe groups, measures of hypoxemia were more strongly correlated with MWT sleep latency. A two-factor analysis of variance using respiratory arousal index and several measures of oxyhemoglobin saturation indicated that both arousals from sleep and degree of hypoxemia contribute interactively to daytime dysfunction in patients with sleep apnea. The MWT appears useful in evaluating disability from daytime sleepiness.

The effects of caffeine on blood pressure in the work environment.

The ambulatory blood pressure and heart rate of twelve healthy volunteers were monitored on two separate days in the participants' work environment. All subjects were studied in a double-blind crossover design while they consumed caffeinated or decaffeinated coffee. We examined them at rest, during a standardized mental arithmetic task, and for 6 h of ambulatory monitoring in their regular work setting (research facility and hospital). On days of drinking caffeinated coffee, both systolic and diastolic blood pressure were consistently elevated at all time points (P less than .0005). In response to the mental arithmetic task, the increase in systolic blood pressure over the resting value was particularly exaggerated on caffeinated coffee (P = .0003). For heart rate, there were no effects from caffeine. The study demonstrates that the blood pressure-elevating effects of caffeine, well-known from laboratory studies, are sufficiently robust to be evident in patients' uncontrolled work environments. It implies the importance of caffeine restriction for hypertensive patients. It also indicates the utility of ambulatory blood pressure techniques in studying the blood pressure effects of various nutritional factors taken ad lib in the real world.

Sleep apnea and essential hypertension: a critical review of the epidemiological evidence for co-morbidity.

This paper reviews the epidemiological literature on the linkage between sleep apnea and essential hypertension. Despite the large number of case reports, general overviews and the wide acceptance of this linkage, surprisingly, only four epidemiological articles were identified. The prevalence of sleep apnea among hypertensives ranged between 26% and 47.8% (mean = 33.6%) across the studies as compared to the estimated prevalence of 0.4% to 1.4% in the general population. There seem to be no consistently replicated risk factors for apnea amongst hypertensives, although older age, relative obesity, and severity of hypertension have been suggested as possible markers for this co-morbidity. The findings require further replication with special efforts at studying: (1) unmedicated hypertensive patients; (2) patients without significant cardiac or renal complications; and (3) patients across a broad range of age, obesity, and severity of hypertension.