Effects of variations in interstimulus interval on activation-flow coupling response and somatosensory evoked potentials with forepaw stimulation in the rat.

In functional neuroimaging studies, the hemodynamic response to functional activation is used as a surrogate marker for neuronal activity, typically in response to task paradigms that use periodic stimuli. With use of a model system of electrical forepaw stimulation in rats (n = 14) with laser-Doppler (LD) monitoring of cerebral blood flow (CBF) changes in the somatosensory cortex, the effects of variations in the interstimulus interval (ISI) on the hemodynamic response to periodic stimuli were examined. A characteristic peak flow response was seen for 4-second stimuli and a peak and plateau response were seen for all 8-second stimuli regardless of ISI. However, both the amplitude of the LD(CBF) response and the integrated response were significantly reduced for shorter ISIs, whereas the baseline flow was not altered. Somatosensory evoked potential responses were also recorded in some rats (n = 8) and remained unchanged for the various ISIs for a particular stimulus duration. These results suggest that the decrease in the LD(CBF) responses observed with shorter ISIs likely represents a refractoriness of the hemodynamic response and not neuronal function. These results may have important implications for the optimization and interpretation of functional activation paradigms that use periodic stimuli.     

The more things change the more they stay the same: a case report of neurology residency experiences

This study compared the neurology residency training experience for a single neurology resident at the University of Pennsylvania from the years 2002-2005. The prevalence of encounters seen during this residency was compared to the prevalence of neurological disorders typically observed by ambulatory neurologists in the United States (US). A total of 1,333 patients were evaluated during this residency. Ischemic stroke/transient ischemic accident, epilepsy, metabolic encephalopathy, peripheral neuropathy, and multiple sclerosis were the most common neurological disorders observed. The four most common reasons for an outpatient visit to a neurologist (i.e., headache/migraine, epilepsy, cerebrovascular disease, and peripheral neuropathy) typically account for approximately 49-55% of all appointments, but only contributed to approximately 40% of patient encounters during this neurology residency. While these results reflect the encounters of a single neurology resident, both the total number and distribution of neurological diagnoses were similar to previous experiences over two decades ago at US academic medical centers despite significant changes in health care delivery and policy. This case report demonstrates that neurology residency programs continue to overemphasize acute management of inpatient neurological disorders compared to outpatient care of more prevalent neurological complaints. Additional measures could be instituted to ensure a broader range of experiences during residency (i.e., online resident log). These methods could allow residency coordinators to identify certain areas of deficiency with regards to exposure to patients for a resident and ensure greater competency during residency.     

Dementia and neurocognitive disorders due to HIV-1 infection

Human immunodeficiency virus-type 1 (HIV-l) infection is the most common preventable and treatable cause of neurocognitive impairment in individuals under age 50 years. Although the incidence of HIV-associated dementia has decreased over the past few years due to combination antiretroviral therapy (cART), the prevalence of less severe HIV-associated neurocognitive impairment continues to increase. HIV-associated neurocognitive impairment is a significant burden to persons living with HIV infection, caregivers, and the health care system. Neurocognitive changes associated with HIV are typically subcortical, consisting of the triad of cognitive, behavior, and motor dysfunction. HIV-associated dementia and HIV-associated neurocognitive impairment are clinical diagnostic syndromes with neuropsychological performance testing, neuroimaging, and cerebral spinal fluid studies providing additional information. With the advent of more effective cART, the incidence of fatal opportunistic complications has dramatically diminished. Accordingly, the present review focuses on primary HIV-induced disease of the central nervous system, rather than its opportunistic complications.     

The Alzheimer’s disease-8 and Montreal Cognitive Assessment as screening tools for neurocognitive impairment in HIV-infected persons

The diagnosis of human immunodeficiency virus (HIV)-associated neurocognitive impairment is time-intensive and often omitted in busy outpatient settings. Brief screening tools are needed. The Montreal Cognitive Assessment (MoCA) and the Alzheimer’s disease (AD)-8 have been used in neurodegenerative disorders. We evaluated the sensitivity and specificity of these brief screening tools in HIV-infected persons. The AD-8, MoCA, and formal neuropsychological testing were administered to 200 HIV-infected patients who were followed at a single institution. Normalized scores on formal neuropsychological testing were used to define neurocognitive impairment. The sensitivity and specificity of the MoCA and AD-8 were assessed to diagnose the impairment. Neurocognitive impairment was highly prevalent in this cohort: 127 persons (64 %) were diagnosed with neurocognitive impairment based on formal testing. Using the AD-8 and MoCA, 113 (57 %) and 101 (51 %) persons were identified with neurocognitive impairment, respectively. The sensitivity and specificity of MoCA were 63 % and 71 %, respectively. The sensitivity and specificity of AD-8 were 61 % and 51 %, respectively. Our findings highlight that brief screening tools correlate with formal neuropsychological testing. However, the sensitivities of these screening tools are lower than desired. Nevertheless, given their ease in administration, these tools could assist as a first line for identifying individuals who may subsequently require formal neuropsychological testing.     

Impact of human immunodeficiency virus on neurocognition and risky behaviors in young adults

Previous studies have identified cognitive impairments due to human immunodeficiency virus (HIV) in adults. However, few studies have examined the impact of HIV on cognition in young adults (18–24 years old). Yet, this group is one of the largest populations of individuals with new HIV infection. Young adulthood is also an important developmental window because the brain has not fully matured and individuals are prone to engage in risky behavior. The purpose of the present study was to examine the impact of HIV on neurocognition and risky behaviors. We hypothesized that HIV+ young adults (n?=?23) would exhibit greater cognitive impairment and risky behaviors compared to seronegative controls (n?=?21). In addition, we predicted that self-reported risky behavior as assessed by the Risk Assessment Battery (RAB) would covary with cognitive performances. Results revealed poorer executive function in HIV+ young adults compared to seronegative (HIV?) controls. HIV+ young adults exhibited significantly greater risk scores on the RAB (p?相似文献   

Plasma Aldosterone Concentration at Delivery and during the Newborn Period

Aldosterone concentrations in plasma of women on normal sodium intake undergoing cesarean section were 3.7+/-1.4 ng/100 ml (mean+/-1 SD). These values were significantly lower (P < 0.001) than those observed in mothers on normal sodium diet, delivered by the vaginal route (14.9+/-7.0 ng/100 ml). A significant elevation (P < 0.001) of the concentrations was found if the mothers had been on sodium restriction and/or diuretics (44.9+/-24.2 ng/100 ml). In supine position, adult nonpregnant subjects have aldosterone concentrations in plasma of 1.7+/-1.4 ng/100 ml on normal sodium intake and of 16.7+/-8.1 ng/100 ml on low sodium diet.Simultaneous determinations of aldosterone levels in cord blood showed that cord values were significantly higher than those of the corresponding mother (P < 0.01 by paired t test). However, values in cord blood of infants born to mothers on a normal sodium intake were significantly lower (P < 0.005) than those of infants whose mothers had required low sodium diet and/or diuretics during their pregnancy.Aldosterone concentrations in plasma of infants 1-72 hr of age and born to mothers on normal sodium intake were 25.9+/-11.7 ng/100 ml (mean +/-1 SD). These values were significantly lower (P < 0.005) than those of infants born to mothers on restricted sodium intake with or without diuretics (80.3+/-54.4 ng/100 ml). The concentrations at birth were not significantly different from those observed during the first 3 days of life (P > 0.6).     

Molecular Imaging of Neuroinflammation in HIV

Journal of Neuroimmune Pharmacology - The development of combined antiretroviral therapy (cART) has increased the lifespan of persons living with HIV (PLWH), with most PLWH having a normal life...