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Biomedical subjects

D B Rye

Publications and source records attributed to D B Rye.

At least 19 recordsLinked to original sources
PubMed2005

Characteristics of idiopathic REM sleep behavior disorder and that associated with MSA and PD.

OBJECTIVE: To compare the clinical and video-polysomnographic (VPSG) characteristics of idiopathic REM sleep behavior disorder (RBD) vs the RBD seen in multiple system atrophy (MSA) and Parkinson disease (PD). METHODS: Clinical features and VPSG measures were evaluated in 110 consecutive nondemented subjects (26 MSA, 45 PD, and 39 idiopathic RBD) free of psychoactive medications referred for suspected RBD to our sleep unit over a 5-year period, with extended follow-up (mean 26.9 +/- 21.3 months). RESULTS: Across the three groups studied, logistic regression analysis demonstrated that there were no differences in the quality of RBD symptoms (e.g., nature of unpleasant dream recall or behaviors witnessed by bed partners), most PSG variables, abnormal behaviors captured by VPSG, and clinical response to clonazepam. When compared to subjects with PD, however, patients with MSA had a significantly shorter duration of disease, a higher REM sleep without atonia percentage, a greater periodic leg movement index, and less total sleep time. Subjects with idiopathic RBD, as compared to those with either MSA or PD, were more often male, had greater self-reported clinical RBD severity, and were more often aware of their abnormal sleep behaviors. CONCLUSIONS: REM sleep behavior disorder (RBD)-related symptoms and neurophysiologic features are qualitatively similar in RBD subjects with the idiopathic form, multiple system atrophy (MSA), and Parkinson disease (PD). Polysomnographic abnormalities associated with RBD in the setting of MSA are greater than in PD, suggesting a more severe dysfunction in the structures that modulate REM sleep.

Age of Onset↗
PubMed2005

Randomized, double-blind, placebo-controlled, short-term trial of ropinirole in restless legs syndrome.

BACKGROUND AND PURPOSE: Restless legs syndrome (RLS) is a condition characterized by an urge to move the legs, usually accompanied by lower limb paresthesias. These symptoms worsen at rest, are relieved by activity, and are worse at night. Previous studies have suggested that dopaminergic drugs such as L-dopa and dopamine agonists, as well as benzodiazepines and opioids, can treat RLS successfully. The purpose of this study was to test the clinical efficacy of ropinirole, a D2/D3 agonist, in the treatment of RLS in a double-blind, short-term, placebo-controlled clinical trial. PATIENTS AND METHODS: After undergoing successful open-label titration and dose adjustments with ropinirole for RLS symptoms over a period of 4 weeks, 22 RLS patients (mean age=50.8; mean duration of symptoms=26.1 years) were randomized to receive either placebo (n=13) or ropinirole (n=9) for 2 additional weeks. Outcome measures included assessment of periodic leg movements in sleep (PLMS) recorded with nocturnal polysomnography and RLS symptoms as assessed with the International Restless Legs Syndrome Study Group (IRLSSG) Rating Scale. Secondary outcomes included sleep macroarchitecture. RESULTS: Results indicated that relative to placebo, ropinirole, at a mean dose of 1.4mg HS significantly decreased PLMS and RLS symptoms. Sleep macroarchitecture did not change. Side effects were typical of all dopamine agonists and were dose related. The majority of patients elected to continue treatment with ropinirole upon study completion. CONCLUSIONS: Ropinirole successfully treated long-standing RLS and can be considered a viable short-term treatment for this condition.

Adult↗
PubMed2003

Episodic neonatal hypoxia evokes executive dysfunction and regionally specific alterations in markers of dopamine signaling.

Perinatal ischemic-anoxic and prolonged anoxic insults lead to impaired dopaminergic signaling and are hypothesized to contribute, at least in part, to the pathogenesis of disorders of minimal brain dysfunction such as attention-deficit hyperactivity disorder. We hypothesized that subtle intermittent hypoxic insults, occurring during a period of critical brain development, are also pathogenic to dopaminergic signaling, thereby contributing to behavioral and executive dysfunction. Between postnatal days 7 and 11, rat pups were exposed to either 20-s bursts of isocapnic hypoxic gas, compressed air, or were left undisturbed with the dam. On postnatal days 23 pups were instrumented with electroencephalographic/electromyographic electrodes and sleep-wake architecture was characterized. Locomotor activity was assessed between postnatal days 35 and 38, learning, and working memory evaluated between postnatal days 53 and 64. Rats were killed on postnatal day 80 and tyrosine hydroxylase, vesicular monoamine transporter, dopamine transporter, and dopamine D1 receptors were quantified in the prefrontal cortex, primary sensorimotor cortex, and precommissural striatum by Western blot analyses. Post-hypoxic pups spent less time awake and more time in rapid-eye-movement sleep during the lights-on phase of the circadian cycle, were hyperlocomotive, and expressed impaired working memory. Striatal expression of vesicular monoamine transporter and D1 receptor proteins were increased in post-hypoxic rats, consistent with depressed dopaminergic signaling. These observations lead to the intriguing hypothesis that intermittent hypoxia occurring during a period of critical brain development evokes behavioral and neurochemical alterations that are long lasting, and consistent with disorders of minimal brain dysfunction.

Animals↗
PubMed2001

Polymorphisms in hypocretin/orexin pathway genes and narcolepsy.

The neuroexcitatory peptide hypocretin and its receptors are central to the pathophysiology of both human and animal models of the disease. In this study of American and Icelandic patients with narcolepsy, the authors found no significant association between narcolepsy and single-nucleotide polymorphisms in the genes for hypocretin or its two known receptors, hypocretin receptor-1 and hypocretin receptor-2.

Adult↗
PubMed2000

Intradialytic subjective sleepiness and oral body temperature.

STUDY OBJECTIVES: Hemodialysis (HD) patients are often observed to sleep during treatment. Because of the well-described, inverse association between body temperature and sleep propensity, the purpose of this study was to describe the course of intradialytic (during HD) subjective sleepiness and examine its relationship to oral body temperature. In addition, we sought to determine if that relationship varied with dialysis treatment time of day. DESIGN: Subjective sleepiness and oral body temperature were recorded every 15 minutes through the entire course of HD. SETTING: The study was conducted at two large, inner-city dialysis units. PATIENTS OR PARTICIPANTS: The sample included 60 chronic HD patients, 20 on each of three shifts based on treatment time of day (shift 1-6:00A.M. to 10:00A.M.; shift 2-10:00A.M. to 2:00P.M.; and shift 3-2:00P.M. to 6:00P.M.. MEASUREMENTS AND RESULTS: Subjects on shift 1 were found to have a mean intradialytic sleepiness level greater than those on shift 2 (p<.04) and shift 3 (p<.003). Irrespective of shift, sleepiness increased during the first half of dialysis and decreased slightly as treatment progressed, a significant quadratic trend (p<.001). During the same period, temperature initially increased, subsequently dropped in temporal proximity to maximal sleepiness and increased again, a significant quadratic trend (p<.02). The relationship between sleepiness and temperature revealed a significant negative correlation (r=-.59, p<.03) and did not vary with treatment time of day. CONCLUSIONS: The results argue that sleep propensity increases during HD, an effect that may be related to treatment induced alterations in arousal and/or thermoregulatory processes. The effect is unrelated to treatment time of day.

Body Temperature↗
PubMed2000

Inter-rater reliability for identification of REM sleep in Parkinson's disease.

Recently described functional connections between basal ganglia and brainstem circuits provide a neurobiologic basis for the absence of REM sleep atonia in Parkinson's disease (PD). However, identifying atypical REM sleep in PD may be problematic. Reliable sleep staging has never been demonstrated in such patients. In this study, 3 experienced scorers independently evaluated overnight polysomnograms from 10 (PD) patients. Results indicated good agreement for distinguishing REM from NREM sleep and waking. Reliable differentiation among NREM stages was more difficult to achieve. The results suggest that, despite suspension of REM sleep atonia accompanying PD, trained scorers can distinguish REM from wakefulness and NREM sleep.

Aged↗
PubMed2000

Dopamine D(5) receptor immunolocalization in rat and monkey brain.

Dopamine D(5) receptor localization has been difficult because even the most specific ligands cannot distinguish between molecular subtypes of the D(1)-like receptor subfamily. Antifusion protein rabbit polyclonal antibodies directed against the C-terminus of human D(5) receptor were therefore developed for immunolocalization of the D(5) receptor protein in brain. The antibodies were characterized by immunoblot analysis and immunoprecipitation and used for light microscopic immunocytochemistry in rat and monkey brain. Affinity purified D(5) antibodies were specific for D(5) fusion protein as well as cloned and native D(5) receptor on Western blots, and D(5) antisera specifically immunoprecipitated solubilized, cloned D(5) receptor. Regional distribution of D(5) receptor immunoreactivity was consistent across species and correlated well with D(5) mRNA distribution previously reported in monkey brain. Immunoreactivity was widespread and tended to label perikarya and proximal dendrites of neurons in cerebral cortex, basal ganglia, basal forebrain, hippocampus, diencephalon, brainstem, and cerebellum. Neuropil was immunoreactive in olfactory bulb, islands of Calleja, cerebral cortex, superior colliculus, and molecular layer of cerebellum. The distribution of D(5) in brain was clearly different from that of other dopamine receptor subtypes, including D(1), the other member of the D(1)-like receptor subfamily. This unique distribution corroborates the idea that the D(5) receptor subtype has a distinct role in dopamine neurotransmission.

Animals↗
PubMed2000

FAST TRACK: daytime sleepiness in Parkinson's disease.

We describe multiple sleep latency test (MSLT) results in 27 adult patients with idiopathic Parkinson's disease (PD). Pathological sleepiness (i.e. mean sleep latency </=5 min) was common (40 of 134 nap opportunities), and sleep-onset REM periods were also observed (13 of 134 nap opportunities). These findings bore little relationship to disease specific variables (e.g. level of disability, medication use), or sleep architecture measures (e.g. total sleep time, sleep stage percentage's). Our findings speak against a simple association of excessive sleepiness and the quality and quantity of prior night's sleep, but rather, argue for primary impairments of waking arousal and REM-sleep expression in a sizeable subpopulation of PD patients.

Aged↗
PubMed1999

Juvenile Parkinson's disease with REM sleep behavior disorder, sleepiness, and daytime REM onset.

We describe an unmedicated patient with juvenile PD with difficulties maintaining wakefulness and the atonia of REM sleep. Laboratory testing showed enhanced muscle activity in REM sleep consistent with a history of dream enactment behavior (i.e., REM sleep behavior disorder) and daytime sleepiness, and REM-sleep onsets on multiple sleep latency testing. The results emphasize the potential role of dopamine and basal ganglia circuits in the modulation of activated behavioral states (e.g., wakefulness and REM sleep).

Adolescent↗
PubMed1999

Immunochemical analysis of vesicular monoamine transporter (VMAT2) protein in Parkinson's disease.

The vesicular monoamine transporter (VMAT2) has been suggested to be an excellent marker of presynaptic dopaminergic nerve terminals in the striatum of Parkinson's disease patients based on its high level of expression and insensitivity to drugs used to treat the disease. Previous in vivo imaging and postmortem binding studies have detected a loss in striatal VMAT2 binding in Parkinson's diseased (PD) brain; however, these techniques have poor spatial resolution and may suffer from nonspecific binding of some ligands. In this study, we use novel polyclonal antibodies to distinct regions of human VMAT2 to quantify and localize the protein. Western blot analysis demonstrated marked reductions in VMAT2 immunoreactivity in putamen, caudate, and nucleus accumbens of PD brain compared to control cases. Immunohistochemistry revealed VMAT2 immunoreactive fibers and puncta that were dense throughout the striatum of control brains, but which were drastically reduced in putamen of PD brains. In PD brains the caudate showed a significant degree of sparing along the border of the lateral ventricle and the nucleus accumbens was relatively preserved. The distribution of VMAT2 in striatum and its loss in PD paralleled that of the dopamine transporter (DAT), a phenotypic marker of dopamine neurons. Thus, immunochemical analysis of VMAT2 protein provides novel and sensitive means for localizing and quantifying VMAT2 protein and nigrostriatal dopamine terminals in PD. Furthermore, the relative expression of VMAT2 compared to that of DAT may predict the differential vulnerability of dopamine neurons in PD.

Animals↗
PubMed1998

Presentation of narcolepsy after 40.

To advance understanding of the clinical spectra of narcolepsy, we retrospectively reviewed the histories and clinical and polysomnographic features of 41 consecutive patients in whom this diagnosis was established in our center over 3 years. A total of 51% presented after the age of 40 years. Among the older patients, three subpopulations were noted: 1) narcolepsy/cataplexy with presentation delayed because of mild disease severity or misdiagnosis; 2) narcolepsy/cataplexy with diagnosis delayed until late-life expression of cataplexy; and 3) narcolepsy lacking cataplexy with later-life onset of excessive daytime sleepiness. Clinical, polysomnographic, and multiple sleep latency test assessments of rapid eye movement sleep dyscontrol and sleepiness were unrelated to age. This analysis identified older patients lacking cataplexy as the least severely affected narcoleptic subgroup. Narcolepsy, a continuum of phenotypes and severities that masks its recognition, should be considered in the differential diagnosis of sleepiness or transient loss of muscle tone in older patients.

Adult↗
PubMed1998

Reversal of atypical depression, sleepiness, and REM-sleep propensity in narcolepsy with bupropion.

We successfully treated a 46-year-old narcoleptic woman suffering from atypical depression with bupropion hydrochloride. Diagnostic evaluation revealed a Beck Depression Inventory (BDI) score of 24, a short nocturnal REM-sleep latency, subjective and objective sleepiness (mean sleep latency (MSL) = 1.8 minutes), and three sleep onset REM-sleep periods during the five nap multiple sleep latency test. Bupropion (100 mg t.i.d.) normalized her mood (BDI = 6), sleepiness (MSL = 9.1 minutes), and REM-sleep propensity. Upon discontinuation of bupropion, these parameters reverted to pretreatment levels. This "activating" antidepressant's reversal of the sleepiness and REM-sleep propensity in narcolepsy may be due to blockade of dopamine or norepinephrine reuptake. Clinicians need to be alert to the fact that depression can mask the diagnosis of narcolepsy. Bupropion warrants further investigation as a treatment for narcolepsy in an open-label, double-blind, placebo-controlled paradigm.

Antidepressive Agents, Second-Generation↗
PubMed1997

Ultrastructural study of cholinergic and noncholinergic neurons in the pars compacta of the rat pedunculopontine tegmental nucleus.

A group of medium-to-large cholinergic neurons situated in the dorsolateral mesopontine tegmentum comprises the pedunculopontine tegmental nucleus (PPT). The PPT pars compacta (PPT-pc), which occupies the lateral part of the caudal two-thirds of the nucleus, contains a dense aggregation of cholinergic neurons. In the present study, we have employed immunohistochemistry for choline acetyltransferase (ChAT) and electron microscopy to investigate the ultrastructure and synaptic organization of neuronal elements in the PPT-pc. Our results demonstrate that: (1) ChAT-immunoreactive (i.e., cholinergic) PPT-pc neurons are characterized by abundant cytoplasm and organelles, and have few axosomatic synapses (both asymmetric and symmetric); (2) ChAT-immunoreactive dendrites comprise 6-15% of total dendritic elements in the neuropil; the mean percentage of dendritic membrane covered by synaptic terminals is approximately 15%, and nearly all synapses with ChAT-immunoreactive dendrites are asymmetric; (3) within the boundaries described by cholinergic PPT-pc, there are noncholinergic neurons which, in contrast, exhibit a lucent cytoplasm and a higher frequency of axosomatic synapses (10.5% versus 3.7% for cholinergic neurons); and (4) noncholinergic neurons are morphologically heterogeneous with one subpopulation exhibiting a mean diameter that approximates that of cholinergic cells (i.e., > 15 microns and < 20 microns) and a very high frequency of axosomatic synapses (> 20%). Only 0.2-0.7% of terminal elements in the neuropil were ChAT-immunoreactive and these were not observed to synapse with cholinergic dendrites or somata. This relative paucity of terminal labeling and lack of cholinergic-cholinergic interactions seems inconsistent with the recognized and prominent physiological actions of acetylcholine on cholinergic PPT-pc neurons, and suggests a methodological limitation and/or a potential paracrine-like action of nonsynaptically released acetylcholine in the PPT region.

Acetylcholine↗