Latent Impairment Research Articles

In Myotonic Dystrophy Type 1 Head Repositioning Errors Suggest Impaired Cervical Proprioception.

Background: Myotonic dystrophy type 1 (DM1) is a rare multisystemic genetic disorder with motor hallmarks of myotonia, muscle weakness and wasting. DM1 patients have an increased risk of falling of multifactorial origin, and proprioceptive and vestibular deficits can contribute to this risk. Abnormalities of muscle spindles in DM1 have been known for years. This observational cross-sectional study was based on the hypothesis of impaired cervical proprioception caused by alterations in the neck spindles. Methods: Head position sense was measured in 16 DM1 patients and 16 age- and gender-matched controls. A head-to-target repositioning test was requested from blindfolded participants. Their head was passively rotated approximately 30° leftward or rightward and flexed or extended approximately 25°. Participants had to replicate the imposed positions. An optoelectronic system was adopted to measure the angular differences between the reproduced and the imposed positions (joint position error, JPE, °) concerning the intended (sagittal, horizontal) and unintended (including the frontal) planar projections. In DM1 patients, JPEs were correlated with clinical and balance measures. Static balance in DM1 patients was assessed through dynamic posturography. Results: The accuracy and precision of head repositioning in the intended sagittal and horizontal error components did not differ between DM1 and controls. On the contrary, DM1 patients showed unintended side-bending to the left and the right: the mean [95%CI] of frontal JPE was -1.29° [-1.99°, -0.60°] for left rotation and 0.98° [0.28°, 1.67°] for right rotation. The frontal JPE of controls did not differ significantly from 0° (left rotation: 0.17° [-0.53°, 0.87°]; right rotation: -0.22° [-0.91°, 0.48°]). Frontal JPE differed between left and right rotation trials (p < 0.001) only in DM1 patients. No correlation was found between JPEs and measures from dynamic posturography and clinical scales. Conclusions: Lateral head bending associated with head rotation may reflect a latent impairment of neck proprioception in DM1 patients.

Atypical 'long-tailed' cockroaches arose during Cretaceous in response to angiosperm terrestrial revolution.

Typical cockroaches are flat, broad, with large pronotum and wings covering the body. This conserved morphotype dates back to the Carboniferous, during which the ancestral cockroaches, or roachoids, originated. On the other hand, the ovipositor of cockroaches gradually reduced during the Mesozoic, coupled with a major shift of reproductive strategy. By the Cretaceous, long external ovipositors became rare, most cockroaches used very short or even hidden internal ovipositors to fabricate egg cases (oothecae), which is an innovation for egg protection. Here, we describe two cockroaches from mid-Cretaceous Myanmar amber: Ensiferoblatta oecanthoides gen. et sp. nov. (Ensiferoblattidae fam. nov.) and Proceroblatta colossea gen. et sp. nov. They are slim, elongate, fusiform, with longitudinal pronotum, and have long external ovipositors. The combination of these traits represents a unique morphotype, which resembles crickets and katydids (Ensifera) more than general cockroaches. Ensiferoblatta and Proceroblatta may be arboreal, feeding on and/or laying eggs into certain angiosperms that newly emerged. Their open habit causes latent impairment to viability, and may contribute to their extinction. These new taxa are the youngest members of the ancient, extinct group of cockroaches, namely Eoblattodea, which are characterized by long ovipositors. We speculate that the extinction of certain gymnosperm hosts almost ended the 200-My triumph of Eoblattodea. Despite an attempt to adapt to angiosperm hosts, Ensiferoblatta, Proceroblatta and suchlike cockroaches as an evolutionary dead end failed to save Eoblattodea from extinction. The lack of protection for eggs (maternal care in particular) might accelerate the extinction of Eoblattodea as a whole.

Potentially disabled?

ABSTRACT Ten years ago, I was diagnosed with a rare illness called Myasthenia Gravis. Myasthenia Gravis is a long-term neuromuscular autoimmune disease where antibodies block or destroy specific receptors at the junction between nerve and muscle; hence, nerve impulses fail to trigger muscle contractions. The disease leads to varying degrees of muscle weakness. Currently, I have only minor symptoms, I am not seriously impaired, and I do not suffer from any social disadvantage because of my illness. Yet, my life and my body since my diagnosis feel different than before. In this paper I aim to make this feeling intelligible and propose that it is a state of what I call ‘latent impairment’. Latent impairment is a state of being ‘in between’, different from being actually impaired and also different from being abled-bodied. The theory takes its cues both from social constructionist theories of disability as well as theories of (chronic) illness and their focus on the importance of subjectivity. Furthermore, I suggest that a phenomenological understanding of latent impairment can show possible ways of becoming an ally to the DRM.

Study of serum cystatin C levels in patients with obstructive sleep apnea

BackgroundSerum cystatin C is a sensitive indicator for early renal impairment in patients with obstructive sleep apnea (OSA). In patients with OSA without known chronic kidney disease (CKD), serum cystatin C was found to be elevated, indicating latent renal disease, which may be caused by recurrent episodes of hypoxemia and reoxygenation that trigger inflammatory process.ObjectiveTo evaluate serum levels of cystatin C in otherwise healthy patients with OSA to predict the future risk of latent renal impairment in these patients.Patients and methodsA total of 30 patients were classified into two groups: group I included 10 healthy controls, and group II included 20 patients with OSA.The following were done: full history taking, clinical examination, pulmonary function tests, subjective evaluation of daytime sleepiness using the Epworth Sleepiness Scale, and overnight polysomnography. Finally, serum cystatin C levels at the end of polysomnography and glomerular filtration rate was calculated using modification of diet in renal disease formula and CKD-Epidemiology Collaboration cystatin equation.ResultsIn patients with OSA, the mean level of serum cystatin C was statistically significantly higher than that in controls. These higher levels were sex, age, and BMI independently. Moreover, serum levels of cystatin C in patients with OSA were significantly correlated with OSA severity (apnea-hypopnea index) and degree of nocturnal hypoxia through positive correlation with total sleep time less than 90%, total sleep time less than 80%, and respiratory disturbance index and negative correlation with average SPO2%, lowest SPO2%, and estimated glomerular filtration rate by CKD-Epidemiology Collaboration cystatin equation.ConclusionsHigher serum levels of cystatin C were detected in patients with OSA without known comorbidities, which indicates that these patients are at a higher risk of developing CKD. Intermittent hypoxia seems to have the main role in the progression of this process.

Stability of delayed HIV dynamics models with two latent reservoirs and immune impairment

The purpose of this paper is to investigate the qualitative behavior of HIV dynamics models with immune impairment. The HIV particles infect both CD4+ T cells and macrophages. Both latently and actively infected cells are incorporated into the models. The models consider multiple discrete or distributed delays to characterize the time between an HIV contact of an uninfected target cell and the creation of mature HIV. The existence and global stability of the steady states are determined by the basic reproduction number. The global stability analysis of the steady states is performed using Lyapunov method. We solve the system of delay differential equations numerically to support the theoretical results.

Profiling heterogeneity of Alzheimer's disease using white-matter impairment factors.

The clinical presentation of Alzheimer's disease (AD) is not unitary as heterogeneity exists in the disease's clinical and anatomical characteristics. MRI studies have revealed that heterogeneous gray matter atrophy patterns are associated with specific traits of cognitive decline. Although white matter (WM) impairment also contributes to AD pathology, its heterogeneity remains unclear. The Latent Dirichlet Allocation (LDA) method is a suitable framework to study heterogeneity and allows to identify latent impairment factors of AD instead of simply mapping an overall disease effect. By exploring whole brain WM skeleton images by using LDA, three latent factors were revealed in AD: a temporal-frontal impairment factor (temporal and frontal lobes, especially hippocampus and para-hippocampus), a parietal factor (parietal lobe, especially precuneus), and a long fibre bundle factor (corpus callosum and superior longitudinal fasciculus). As revealed by longitudinal analysis, the latent factors have distinct impact on cognitive decline: for executive function (EF), the temporal-frontal factor was more strongly associated with baseline EF compared with the parietal factor, while the long-fibre bundle factor was most associated with decline rate of EF; for memory, the three factors showed almost equal effect on the baseline memory and decline rate. For each participant, LDA estimates his/her composition profile of latent impairment factors, which indicates disease subtype. We also found that the APOE genotype affects the AD subtype. Specifically, APOE ε4 was more associated with the long fibre bundle factor and APOE ε2 was more associated with temporal-frontal factor. By investigating heterogeneity and subtypes of AD through white matter impairment factors, our study could facilitate precision medicine.

Pharmacogenetics of antipsychotic-induced movement disorders as a resource for better understanding Parkinson's disease modifier genes.

Antipsychotic-induced movement disorders are major side effects of antipsychotic drugs among schizophrenia patients, and include antipsychotic-induced parkinsonism (AIP) and tardive dyskinesia (TD). Substantial pharmacogenetic work has been done in this field, and several susceptibility variants have been suggested. In this paper, the genetics of antipsychotic-induced movement disorders is considered in a broader context. We hypothesize that genetic variants that are risk factors for AIP and TD may provide insights into the pathophysiology of motor symptoms in Parkinson’s disease (PD). Since loss of dopaminergic stimulation (albeit pharmacological in AIP and degenerative in PD) is shared by the two clinical entities, genes associated with susceptibility to AIP may be modifier genes that influence clinical expression of PD motor sub-phenotypes, such as age at onset, disease severity, or rate of progression. This is due to their possible functional influence on compensatory mechanisms for striatal dopamine loss. Better compensatory potential might be beneficial at the early and later stages of the PD course. AIP vulnerability variants could also be related to latent impairment in the nigrostriatal pathway, affecting its functionality, and leading to subclinical dopaminergic deficits in the striatum. Susceptibility of PD patients to early development of l-DOPA induced dyskinesia (LID) is an additional relevant sub-phenotype. LID might share a common genetic background with TD, with which it shares clinical features. Genetic risk variants may predispose to both phenotypes, exerting a pleiotropic effect. According to this hypothesis, elucidating the genetics of antipsychotic-induced movement disorders may advance our understanding of multiple aspects of PD and it clinical course, rendering this a potentially rewarding field of study.

Concord grape juice reverses the age-related impairment in latent learning in rats

ObjectiveTwo experiments were conducted to determine if dietary supplementation with Concord grape juice could reverse the latent learning impairment normally observed in middle-aged male rats.MethodsBoth experiments utilized the latent cue preference (LCP) task, in which water-replete rats sample water in one compartment of a three-compartment box, and are subsequently given a compartment preference test when water-deprived to determine if they remember the compartment cue previously associated with water. In the first experiment, 40 male Sprague-Dawley rats (9, 10, 11, or 12 months old) were used to determine the age of onset of the impairment. In the second experiment, 24 male Sprague-Dawley rats (11 months old) were given daily access (10 ml/day) to 50% Concord grape juice, 50% white grape juice, or a calorically-equivalent sugar solution daily for 5 weeks prior to training.ResultsThe first experiment revealed that the latent learning impairment begins to manifest at 10 months of age in the male rats and is fully present at 11 months. The second experiment showed that rats that consumed the 50% Concord grape juice for 5 weeks beginning at 11 months of age showed intact latent learning in the LCP task, while rats that consumed the other two supplements showed the normal impairment on the LCP task.DiscussionThese results indicate that daily supplementation with Concord grape juice was able to reverse the latent learning impairment normally seen in middle-aged male rats. This reversal is most likely due to the presence of flavonoids in Concord grape juice.

Impaired brain activity in cirrhotic patients with minimal hepatic encephalopathy: Evaluation by near-infrared spectroscopy

Near-infrared spectroscopy (NIRS) is a tool that could non-invasively measure the regional cerebral oxygenated hemoglobin (oxy-Hb) concentration with high time resolution. The aim of the present study is to reveal the time-dependent regional cerebral oxy-Hb concentration change coupled with brain activity during task performance in patients with minimal hepatic encephalopathy (MHE). Cerebral oxy-Hb concentration was measured by using NIRS in 29 cirrhotic patients without overt hepatic encephalopathy (HE). Of those, 16 patients who had abnormal electroencephalography findings were defined as having MHE. Responsive increase in oxy-Hb during a word-fluency task was compared between MHE and non-MHE patients. There was no difference in the maximum value of oxy-Hb increase between patients with and without MHE (0.26 ± 0.12 vs 0.32 ± 0.22 mM·mm, P = 0.37). However, the pattern of the time course changes of oxy-Hb was different between the two groups. The MHE group was characterized by a gradual increase of oxy-Hb throughout the task compared to steep and repetitive increase in the non-MHE group. Increase in oxy-Hb concentration at 5 s after starting the task was significantly small in the MHE group compared to the non-MHE (0.03 ± 0.05 vs 0.11 ± 0.09 mM·mm, P = 0.006). The cerebral oxygen concentration is poorly reactive in response to tasks among cirrhotic patients without overt HE but having abnormal electroencephalography findings. These impaired responses in regional cerebral oxy-Hb concentration may be related to the latent impairment of brain activity seen in MHE.

Fear of Injury Predicts Self-Reported and Behavioral Impairment in Patients With Chronic Low Back Pain

Fear of injury has been posited as crucial in pain-related anxiety and in the development of chronic pain; however, research has only measured fear of injury indirectly through other constructs (eg, fear of illness and fear of movement). The current study tested fear of injury as an independent contributor to pain-related anxiety and impairment. Patients (n = 78; 37% women) in a work-hardening treatment program for chronic low back pain completed self-report measures of pain-related anxiety, anxiety sensitivity, fear of injury, current pain, and impairment. Behavioral measures of impairment included lifting capacity, treatment outcomes, and days absent from treatment. Structural equation modeling tested the role of fear of injury within contemporary theory. Fit for the theoretical model was excellent and superior to an alternative model. Variance accounted for in pain-related anxiety by fear of injury, anxiety sensitivity, and current pain was 64%, while pain-related anxiety and current pain predicted 49% of variance in latent impairment. Fear of injury directly predicted pain-related anxiety (β = .42) and indirectly predicted impairment through pain-related anxiety (β = .19). Fear of injury may warrant theoretical and clinical consideration as an important contributor to pain-related anxiety and impairment; however, research is needed to explore how it may be causally related with other constructs. PerspectiveFear of injury directly predicts pain-related anxiety and indirectly predicts self-reported and behavioral impairment. Fear of injury may warrant inclusion in contemporary theories of chronic pain. Clinicians may benefit from considering the construct in interventions for chronic pain.

Altered Cognitive Function of Prefrontal Cortex During Error Feedback in Patients With Irritable Bowel Syndrome, Based on fMRI and Dynamic Causal Modeling

Patients with irritable bowel syndrome (IBS) have increased activity in the insula and reduced activation of the dorsolateral prefrontal cortex (DLPFC) in response to visceral stimulation. We investigated whether they have latent impairments in cognitive flexibility because of dysfunction in the DLPFC and insula and altered connectivity between brain regions. We analyzed data from 30 individuals with IBS (15 men; age, 21.7 ± 3.0 y) diagnosed based on Rome III criteria, along with 30 individuals matched for age, sex, and education level (controls). Event-related functional magnetic resonance imaging of the brain was performed to evaluate cognitive flexibility and was assessed by the Wisconsin Card Sorting Test, in which subjects are allowed to change choice criteria, defined as set-shifting in response to error feedback. Brain images were analyzed with statistical parametric mapping 5 and 8 software and dynamic causal modeling. Subjects with IBS had significantly more Nelson perseverative errors (P < .05) and set-maintenance difficulties (P < .05) than controls. They also showed significantly decreased activity of the right DLPFC (Brodmann's area 9; P < .001) and right hippocampus (P < .001), and significantly increased activity of the left posterior insula (P < .001) at error feedback during set-shifting. Dynamic causal modeling analysis during set-shifting revealed significantly less connectivity from the DLPFC to pre-supplementary motor area in subjects with IBS, compared with controls (P = .012). Individuals with IBS have latent impairments in cognitive flexibility as a result of altered activity of the DLPFC, insula, and hippocampus, and impaired connectivity between the DLPFC and pre-supplementary motor area.

Diagnosis, Prevention, and Management of Delirium in the ICU

Delirium is a frequent yet underrecognized complication in the ICU that is characterized by fluctuating disturbances in cognition and consciousness. Rapid identification, investigation of possible etiologies, and management of this syndrome is essential, as it has serious immediate and long-term consequences for patients, including increased mortality, longer hospital stays, and possible latent cognitive impairments. Prevention of delirium includes nonpharmacologic interventions such as daily awakenings, early mobilization, and careful choice of sedatives. Management of delirium includes numerous nonpharmacologic environmental measures such as frequent reorientation, minimizing interventions, and removal of restraints, as well as treatment of the underlying etiology. Medical management, which includes management of symptoms with medications such as antipsychotics, is likely overused. Further research is critical to delineate ideal methods in prevention and treatment of this disorder.

Effects of Stress on Decision-Making Deficits in Formerly Heroin-Dependent Patients After Different Durations of Abstinence

Drug abuse is associated with substantial impairments in decision making. However, little is known about the time course of changes in decision-making ability after abstinence or about the effects of stress on decision making in individuals recovering from heroin dependence after different durations of abstinence. First, the authors assessed decision-making performance with the original card version of the Iowa Gambling Task in formerly heroin-dependent patients who had been abstinent for 3, 7, 15, or 30 days or 3, 6, 12, or 24 months. Second, patients who had been abstinent from heroin for 15 or 30 days or 3, 12, or 24 months were challenged with acute stress induced by the Trier Social Stress Test. Third, the β-adrenoceptor antagonist propranolol (40 mg) was administered 1 hour before stress to those who had been abstinent for 30 days or 12 or 24 months. The short-term abstinence groups (3-30 days) performed worse on the Iowa Gambling Task compared with the long-term abstinence groups (3-24 months). Psychosocial stress unmasked a latent impairment in decision making in the 24-month abstinence group, which seemed to perform identically to healthy comparison subjects in the absence of stress. Propranolol blocked the stress-induced impairment of decision making, which was seen only in the formerly heroin-dependent patients. Stress can exacerbate an already existing impairment of decision making or unmask a latent one in individuals recovering from heroin dependence. The β-adrenergic blockade reduces this effect and might hold promise for treatment of substance use disorders.

Behavioral effects of subchronic inhalation of toluene in adult rats

Whereas the acute neurobehavioral effects of toluene are robust and well characterized, evidence for persistent effects of repeated exposure to this industrial solvent is less compelling. The present experiment sought to determine whether subchronic inhalation of toluene caused persistent behavioral changes in rats. Adult male Long–Evans rats inhaled toluene vapor (0, 10, 100, or 1000 ppm) for 6 h/day, 5 days/week for 13 weeks and were evaluated on a series of behavioral tests beginning 3 days after the end of exposure. Toluene delayed appetitively-motivated acquisition of a lever-press response, but did not affect motor activity, anxiety-related behavior in the elevated plus maze, trace fear conditioning, acquisition of an appetitively-motivated visual discrimination, or performance of a visual signal detection task. Challenges with acute inhalation of toluene vapor (1200–2400 ppm for 1 h) and injections of quinpirole (0.01–0.03 mg/kg) and raclopride (0.03–0.10 mg/kg) revealed no toluene-induced latent impairments in visual signal detection. These results are consistent with a pattern of subtle and inconsistent long-term effects of daily exposure to toluene vapor, in contrast to robust and reliable effects of acute inhalation of the solvent.

The Environmental History of Human-Induced Impacts to the Lake Pontchartrain Basin in Southeastern Louisiana since European Settlement—1718 to 2002

The Lake Pontchartrain Basin in southeast Louisiana is a 9645 mi2 (24,980 km2) area composed of low-lying coastal forests hydrologically coupled with deltaic estuaries associated with the Mississippi River and the Gulf of Mexico. The two largest cities in Louisiana, New Orleans and Baton Rouge, are within the basin. Since European settlement in 1718, population increase, landscape modifications, accidental events, and exploitation of natural resources have had a profound impact on the natural landscape.A database of several hundred environmental impacts from 1718 to 2002 was developed. Examples of impacts are introduction of invasive species, extirpation of species, deforestation, dredging of wetlands, land clearing, Mississippi River modifications, oil and gas activities, the development of superfund (contamination) sites, and water pollution. The chronology was evaluated four ways to identify the most significant ecologic impacts. Based on the analyses of the chronology, five periods of anthropogenic activity are proposed to have resulted in the most significant negative impacts to the Lake Pontchartrain Basin since European settlement in 1718. These five periods are:Land clearing and settlement of natural levees and ridges from 1718 to 1844 Construction of artificial levees along the Mississippi River from 1844 to 1900 Deforestation of virgin forests by commercial logging from 1890 to 1938 Dredging and armoring of estuaries from1930 to 1974 Increases in water pollution from 1950 to 2002These selected activities affected approximately 76% of the area of the basin and may have reduced habitat quality by 50% initially, which later recovered to nearly 60% functionality. Generally, these impacts still result in latent impairment or increasing damage. Three of the periods contribute significantly to the wetland land-loss crisis in southeast Louisiana.The near 300-year legacy represents unsustainable land or natural resource utilization. Many of the impacts predate modern physical and biological techniques, and, therefore, a true baseline of conditions without alteration by European settlers is poorly known for the Lake Pontchartrain Basin.

The effects of plyometric exercise on unilateral balance performance

The purpose of this study was to determine the effects of plyometric exercise on unilateral balance performance. Nine healthy adults performed baseline measurements on the dominant limb that consisted of: a 20-s unilateral stability test on a tilt balance board, where a higher stability index represented deterioration in balance performance; isokinetic plantar flexion torque at 0.52 and 3.14 rad · s−1; muscle soreness in the calf region; and resting plantar flexion angle. Plyometric exercise consisted of 200 counter-movement jumps designed to elicit symptoms of muscle damage, after which baseline measurements were repeated at 30 min, 24, 48, and 72 h. Perceived muscle soreness of the calf region increased significantly following the plyometric exercise protocol (F4,32 = 17.24, P < 0.01). Peak torque was significantly reduced after the plyometric exercise protocol (F4,32 = 7.49, P < 0.05), with greater loss of force at the lower angular velocity (F4,32 = 3.46, P < 0.05), while resting plantar flexion angle was not significantly altered compared with baseline values (P > 0.05). The stability index was significantly increased (F4,32 = 3.10, P < 0.05) above baseline (mean 2.3, s = 0.3) at 24 h (3.3, s = 0.4), after which values recovered. These results indicate that there is a latent impairment of balance performance following a bout of plyometric exercise, which has implications for both the use of skill-based activities and for increased injury risk following high-intensity plyometric training.

Quality of life in elderly with atherosclerotic diseases

To maintain the good quality of life in elderly, it is important to diagnose and asymptomatic advanced or prone to rupture atherosclerosis by using non-invasive techniques and it is also important to treat and prevent the progression of atherosclerotic disease. Comprehensive geriatric assessment is useful for maintain the good quality of life as well as evaluation of activity of daily life. Treadmill exercise test which protocol was arranged for Japanese elderly revealed high incidences of coronary ischemia susceptible patients in elderly diabetic patients. Concomitant measurement of blood pressure of lower extremities is also useful for early diagnosis of arteriosclerosis obliterence. Vascular endocrinological examination such as brain natriuretic peptide is expectable for early diagnosis of latent impairment of cardiac function. Evaluation of endothelial function by measuring flow mediated dilatation and evaluation of narrowing carotid artery by using ultrasound echocardiograph is useful. These examinations are expectable for future treatment of elderly patients.

Sustained influence of the renal nerves to attenuate sodium retention in angiotensin hypertension.

Recent studies indicate that baroreflex suppression of renal sympathetic nerve activity is sustained for up to 5 days of ANG II infusion; however, steady-state conditions are not associated with ANG II hypertension of this short duration. Thus the major goal of this study was to determine whether neurally induced increments in renal excretory function during chronic intravenous infusion of ANG II are sustained under more chronic conditions when hypertension is stable and sodium balance is achieved. Experiments were conducted in five conscious dogs subjected to unilateral renal denervation and surgical division of the urinary bladder into hemibladders to allow separate 24-h urine collection from denervated (Den) and innervated (Inn) kidneys. ANG II was infused after control measurements for 10 days at a rate of 5 ng. kg(-1). min(-1). Twenty-four-hour control values for mean arterial pressure (MAP) and the ratio for urinary sodium excretion from Den and Inn kidneys (Den/Inn) were 92 +/- 4 mmHg and 0.99 +/- 0.05, respectively. On days 8-10 of ANG II infusion, MAP was stable (+30 +/- 3 mmHg) and sodium balance was achieved. Whereas equal amounts of sodium were excreted from the kidneys during the control period, throughout ANG II infusion there was a greater rate of sodium excretion from Inn vs. Den kidneys (day 10 Den/Inn sodium = 0.56 +/- 0.05), indicating chronic suppression of renal sympathetic nerve activity. The greater rate of sodium excretion in Inn vs. Den kidneys during renal sympathoinhibition also revealed a latent impairment in sodium excretion from Den kidneys. Although the Den/Inn for sodium and the major metabolites of nitric oxide (NO) decreased in parallel during ANG II hypertension, the Den/Inn for cGMP, a second messenger of NO, remained at control levels throughout this study. This disparity fails to support the notion that a deficiency in NO production and action in Den kidneys accounts for the impaired sodium excretion. Most importantly, these results support the contention that baroreflex suppression of renal sympathetic nerve activity is sustained during chronic ANG II hypertension, a response that may play an important role in attenuating the rise in arterial pressure.

Clinical application of magnetoencephalography in a patient with corticobasal degeneration.

Previous neuroimaging studies in corticobasal degeneration (CBD), such as MRI and positron emission tomography, showed lateralized cortical atrophy and a decrease in cortical oxygen metabolism, respectively. The advantage of magnetoencephalography in the research of the auditory system is that activity of both hemispheres can be detected separately. Auditory-evoked magnetic fields (AEFs) were then applied to a patient with corticobasal degeneration. The strength of N100m equivalent current dipoles (ECD) in left hemisphere was extremely smaller (20 nAm) than that in right hemisphere (48 nAm). This results implies that CBD patient might have a decrease in the number of neurons in the primary auditory cortex. This study suggests that AEF measurement is one of the most powerful tools for detecting latent impairment of auditory function in patients with corticobasal degeneration.

Intra-arterial blood pressure monitoring in the evaluation of the hypertensive athlete

To compare the blood pressure (BP) changes during a long-distance run with those during bicycle ergometry, nine normotensive and 18 hypertensive joggers were studied by means of ambulatory intra-arterial monitoring. In all subjects the ergometric test caused a progressive increase in systolic and little change in diastolic BP. Exertional BP levels were closely related to pre-exercise baseline values (P less than 0.001). A different BP pattern was observed during track running, as a sharp rise in systolic BP reaching maximum values 2-4 min after the start was recorded. Subsequently, systolic BP progressively declined throughout the run, only to increase again during the final sprint. Diastolic BP fell markedly at the onset of the run and then remained substantially stable throughout. A poor relationship was observed between the BP values at peak exercise and baseline levels (P less than 0.05) as the normotensives showed a significantly higher BP response than the hypertensives. On the contrary, during the ergometric test a parallel increase in BP was recorded in the normotensive and the hypertensive joggers. No correlation was found between the BP response to track running and to bicycle ergometry. These results indicate that the BP response to a standard stress test is not predictive of the BP changes determined by a long-distance run. The BP increase with strenuous effort seems to be reduced in hypertensive individuals, probably because of latent impairment of cardiac performance.