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Biomedical subjects

W B Mendelson

Publications and source records attributed to W B Mendelson.

At least 73 records · Page 4Linked to original sources
PubMed1992

A comparison of sleep-disordered respiration in ESRD patients receiving hemodialysis and peritoneal dialysis.

STUDY OBJECTIVE: To compare sleep-disordered respiration in ESRD patients receiving peritoneal dialysis and hemodialysis. DESIGN: Subjective and objective measures of sleep were recorded in two groups of ESRD patients receiving PD and HD. SETTING: Tertiary-referral university hospital PATIENTS AND METHODS: Fifteen PD patients (12 males, 3 females) and 15 HD patients (11 males, 4 females) were studied for two nights in the sleep laboratory. RESULTS: Ten of the 15 PD patients and 8 of the 15 HD patients reported multiple types of sleep difficulties (NS). In the PD group, seven described substantial difficulty initially going to sleep; ten were troubled by awakenings during the night, while seven suffered from daytime sleepiness. In the HD group, seven described substantial difficulty initially going to sleep; eight were troubled by awakenings during the night, while five experienced day-time sleepiness. No significant difference was observed in total sleep time, intermittent wake time, sleep latency, sleep efficiency, total disordered breathing events, minimum oxygen saturation and periodic leg movements between the PD and HD groups. Sleep apnea was noted in 9 of 15 PD and 8 of 15 HD patients. CONCLUSIONS: This study indicates that the incidence and severity of sleep apnea is similar in ESRD patients receiving chronic peritoneal dialysis and hemodialysis.

Female↗
PubMed1992

Clinical distinctions between long-acting and short-acting benzodiazepines.

After their clinical introduction in the 1960s, the benzodiazepines rapidly became the most widely prescribed sedative/hypnotics because of their many advantages over barbiturates and other older agents. Along with this popularity came controversy, which has continued to this day. The most recent form this has taken has been the concern that the short-acting benzodiazepines may have a predisposition to induce certain forms of clinical complications. The author reviews the historical framework in which this controversy arose. In the late 1970s and early 1980s, it became increasingly clear that long-acting agents were associated with daytime sedation as well as cognitive and psychomotor impairment, particularly in the elderly. The short-acting benzodiazepines, which greatly reduced the frequency of these types of effects, rapidly became the most widely prescribed agents. A growing body of data indicates that the short-acting hypnotics are less likely to be associated with falls and hip fractures in the elderly and also have less respiratory depressant qualities, compared with the older long-acting agents. The short-acting compounds may also be more efficacious in inducing sleep during the first night of administration. In contrast, the long-acting agents may be more desirable in those cases in which daytime sedation is desired and may be associated with a delayed and milder withdrawal sleep disturbance. With the short-acting agents, however, sleep disturbance upon drug cessation is dose dependent and may be greatly reduced by tapering the dose.

Accidental Falls↗
PubMed1992

Sleep related respiratory disorders in end-stage renal disease patients on peritoneal dialysis.

STUDY OBJECTIVE: To assess the possible effects of peritoneal dialysis (PD) on sleep-related respiration, which might result from dialysate bulk load in the abdomen and/or alterations in metabolic control of respiration during sleep. DESIGN: Subjective and objective measures of sleep were prospectively compared on randomly assigned nights with PD fluid (2.0 L) and without PD fluid in the peritoneal cavity in 11 end-stage renal disease (ESRD) patients on PD. SETTING: Tertiary-referral university hospital. PATIENTS AND METHODS: Fifteen consecutive patients on peritoneal dialysis who complained of chronic sleep disturbance and requested sedative were selected. Four patients declined polysomnographic studies. Consequently, 11 ESRD patients (8 males and 3 females) with a mean age of 63 +/- 4 (SEM) years were studied. RESULTS: Eight of the 11 patients reported multiple types of sleep difficulties. Polysomnographic recordings revealed significant primarily obstructive sleep apnea in 6 of 11 patients on at least 1 of 2 nights. Arterial blood pH, paO2, and paCO2 did not differ between nights with and without PD fluid in the peritoneal cavity in the group as a whole. In the 6 patients with sleep apnea, PaO2 was significantly lower (p less than 0.05) during the night with (PaO2 = 78 +/- 7 mmHg) than during the night without PD fluid (PaO2 = 92 +/- 4 mmHg). In the apneic patients, the amount of dialysate drained in the morning was negatively correlated with the minimum arterial oxygen saturation during the night (r = -0.94; p less than 0.005). CONCLUSIONS: This study indicates a significant relationship between PD patients with chronic sleep disturbance and sleep apnea syndrome. These data suggest that apneic patients may be susceptible to complications of dialysate bulk effect on oxygen desaturation.

Female↗
PubMed1991

An overview of chronic fatigue syndrome.

BACKGROUND: Psychological and immunologic factors both appear to contribute to chronic fatigue syndrome (CFS). By comparing CFS with other disorders in which fatigue is a prominent symptom, the association between fatigue, psychological vulnerability, depression, and immune function may be further defined. Recent data from psychological, neurologic, and immunologic studies that address these issues are reviewed. METHOD: Articles and abstracts covering CFS and related topics of fatigue, depression, and postinfectious syndromes were identified through MEDLINE and Index Medicus (1980-1990) and by bibliographic review of pertinent review articles. RESULTS: The 1988 definition of CFS by the Centers for Disease Control encompasses several conditions in which the major characteristic is severe fatigue associated with constitutional symptoms. Several studies have identified immune dysfunction in CFS patients, but the specificity of these findings remains unclear. Most studies have shown that CFS patients, compared with other patients with chronic medical illness, experience more disabling fatigue. Some investigators have found a higher incidence of concurrent and past psychiatric illness in CFS patients compared with other medical patients, thereby suggesting an underlying psychopathology in CFS. However, other studies have not found a higher than expected incidence of past depression in CFS patients and have further shown that many CFS patients have no identifiable psychopathology. CONCLUSION: CFS appears to be a heterogenous entity. Although there may be a high coincidence of major depression in CFS, a substantial proportion of patients lack any identifiable DSM-III-R psychiatric disorder yet still manifest the syndrome, thereby suggesting it has an autonomous entity. Despite the evolving nature of our current understanding of CFS, a rational diagnostic and therapeutic approach to CFS is possible.

Comorbidity↗
PubMed1990

Effects of muscimol and flurazepam on the sleep EEG in the rat.

In order to assess the possible role of GABA receptor function in the hypnotic property of benzodiazepines, we have examined the sleep EEG in rats given the GABA agonist muscimol, alone and in combination with flurazepam. Muscimol 0.05 and 0.1 mg/kg IP failed to alter sleep latency or total sleep time, and did not interact with the sleep-enhancing properties of flurazepam 20 mg/kg IP. These observations, in conjunction with a previous study of bicuculline, suggest that the hypnotic property of benzodiazepines may not be mediated by alteration of GABAergic activity.

Animals↗
PubMed1990

The search for the hypnogenic center.

1. Electrophysiological and lesion studies have suggested that a number of specific sites in the brainstem and basal forebrain may be involved in the regulation of sleep and waking. In contrast, a study of glucose consumption as measured by the 2-deoxyglucose technique reported a generalized decrease in nonREM sleep compared to waking. The rate of protein synthesis was relatively unchanged in nonREM sleep. 2. Another approach to understanding sleep regulation is to study the mechanism by which hypnotic drugs affect the nervous system. This may be done at both a molecular and neuroanatomic level. Studies with B-carbolines, inverse agonists of benzodiazepines (BZs), indicate that sleep induction by BZs is mediated by binding at the BZ recognition site of the BZ receptor complex. Binding at this site by a long-acting B-carboline parallels the time course of its arousing effects. A study with an enantiomeric BZ indicates that the effects on sleep are stereospecific. It is conceivable that some inverse agonists or enantiomeric benzodiazepines might be developed for clinical use as analeptics. 3. Microinjection of a BZ into the dorsal raphe nucleus acutely increases wakefulness, while administration into the medial preoptic area of the hypothalamus enhances sleep maintenance.

Animals↗
PubMed1990

Effects of buspirone on sleep and respiration.

Drugs used in the treatment of anxiety are frequently sedating and tend to be respiratory depressants. Buspirone, a nonbenzodiazepine anxiolytic agent, has little reported sedative effect. It has been shown to be a respiratory stimulant in an anesthetized, glomectomized cat model. In this study, we examined the effects of two intraperitoneal single doses (10 and 20 mg/kg) of buspirone on sleep and respiration in unanesthetized, intact, freely moving rats. Buspirone increased sleep latency (p less than 0.0001) and decreased total sleep (p less than 0.02) through reductions in both non-REM and REM sleep. Respiratory rate (p less than 0.0003) and ventilation (p less than 0.004) were significantly increased for 4 h after drug injection. The effects on respiration were independent of those on sleep; stimulation was evident in both waking and non-REM sleep. This study suggests that buspirone, in addition to being free of sedating and respiratory depressant side effects when prescribed for anxiety in humans, may be a respiratory stimulant whose effects persist in sleep.

Animals↗
PubMed1990

Clinical neuropharmacology of sleep.

Sleep affects, and is in turn affected by, cardiovascular, thermal, respiratory, endocrine, circadian, and sensory processes. Integrative areas of the basal forebrain play a crucial role, as does interaction with cholinergic and aminergic areas of the brain stem. AD, which affects a wide range of structures and functions, alters sleep in a manner distinguishable from depressive pseudodementia and may involve changes in autonomic function. Sleep apnea occurs with a high incidence in patients with AD, and the possibility should be explored that treating sleep apnea might be beneficial to their cognitive and affective status. Long-acting hypnotics can adversely affect daytime functioning. This might occur because of either direct effects on structures mediating sleep and cognition or, alternatively, exacerbation of sleep-related respiratory dysfunction. Studies of the benzodiazepine receptor complex may lead to the development of new drugs to aid sleep and wakefulness.

Alzheimer Disease↗
PubMed1990

Melatonin administration in insomnia.

Ten patients with persistent insomnia were randomized in a double-blind design and the effects of 1-mg and 5-mg oral dosages of melatonin on the electroencephalogram-recorded sleep were examined. Subjects showed no changes in either the onset or duration of sleep, nor any effect on mood or alertness the following day. A significant increase in rapid-eye-movement (REM) latency was noted at the 1-mg dose, though no other parameter of REM sleep was affected. The patients reported less sleep on both melatonin conditions. Despite this perception of decrease, overall subjective quality was reported to be improved.

Adult↗
PubMed1990

Effects of hemodialysis on sleep apnea syndrome in end-stage renal disease.

A high prevalence of sleep apnea syndrome has been reported in previous studies of patients with chronic renal failure. The possible effects of chronic hemodialysis on the magnitude and severity of sleep apnea have not yet been clarified. The present study was undertaken to understand this relationship, by examining subjective and objective measures of sleep on nights following hemodialysis compared to those without hemodialysis. Significant sleep apnea was noted in 6 of 11 patients. The percentage of apnea time comprised of obstructive apneas increased significantly on the nights following hemodialysis. No significant differences occurred between these nights in the subjective or EEG measures of sleep, or in the total number of disordered breathing events or level of arterial oxygen desaturation. The association between end-stage renal disease (ESRD) and sleep apnea syndrome remains highly significant, but seems not to be acutely altered by conventional hemodialysis treatment.

Female↗
PubMed1989

Evidence for the presence of a benzodiazepine receptor binding substance in cerebrospinal fluid of a rabbit model of hepatic encephalopathy.

Based on the reversal of hepatic encephalopathy in animal models with administration of specific benzodiazepine receptor antagonists, it has been postulated that this syndrome may be mediated by an endogenous benzodiazepine-like compound. In this study using a radio-receptor assay, evidence for the existence of this substance has been demonstrated in cerebrospinal fluid but not sera of rabbits with hepatic encephalopathy due to galactosamine-induced hepature failure. Cerebrospinal fluid from rabbits with hepatic encephalopathy caused 36.1 +/- 5.03% displacement of 3H-Ro 15-1788 specific binding to cortical benzodiazepine receptors, compared to 11.7 +/- 0.76% in control animals (P less than 0.01). The benzodiazepine receptor binding activity has been shown to behave as a competitive inhibitor of radiolabeled benzodiazepine receptor binding. The finding of endogenous benzodiazepine binding activity affords a potential explanation for the amelioration of hepatic encephalopathy in this model with the administration of benzodiazepine receptor antagonists.

Aminocaproates↗
PubMed1989

Sleep apnea syndrome in chronic renal disease.

PURPOSE: We performed this study in order to expand on an earlier report indicating a high prevalence of the sleep apnea syndrome in male patients with end-stage renal disease treated with hemodialysis and to determine whether patients with chronic renal insufficiency (prior to the initiation of therapy for end-stage renal disease) and female patients with end-stage renal disease treated with hemodialysis were affected. PATIENTS AND METHODS: Polysomnography was performed in 26 male and female patients with chronic renal insufficiency and end-stage renal disease treated with hemodialysis who were not receiving testosterone. They included 22 whose histories were suggestive of sleep apnea ("symptomatic") and four whose histories were not ("asymptomatic"). RESULTS: Sixteen of the symptomatic (73 percent) and none of the asymptomatic patients were found to have clinically significant sleep apnea syndrome (p less than 0.02). Both female patients and patients with chronic renal insufficiency had sleep apnea. In nine of these 16 cases, the disorder was primarily of the obstructive type. CONCLUSION: These preliminary data raise the possibility of an association of chronic renal disease and the sleep apnea syndrome, and suggest that some of the daytime sleepiness and disturbed nocturnal sleep in such patients may be related to sleep apnea. They also indicate that questioning patients with chronic renal disease and symptoms suggestive of a sleep disorder is useful in determining who are at high risk for the sleep apnea syndrome. Further study is required to establish a causal relationship between chronic renal disease and the sleep apnea syndrome, and to determine the prevalence of the latter in patients with end-stage renal disease.

Adult↗
PubMed1989

Effect of exertion on the stimulation of ornithine decarboxylase activity by growth hormone in rats.

To investigate the effect of stressful stimulation on tissue responsiveness to growth hormone (GH), we examined ODC activity as a measure of hepatic sensitivity to the hormone during forced exertion in rats. GH caused a 15-fold increase in ODC activity in the livers of resting rats at 3 hours after the injection of hormone. Forced walking in a rotating cylinder enhanced the effect of GH on ODC activity by up to 66% above the effect in resting rats, and this enhancement was positively related to the speed of rotation of the cylinder. These results suggest that tissue hypersensitivity to GH stimulation is a consequence of forced exertion. This hypersensitivity to GH would tend to compensate for the inhibitory effects of forced exertion on GH secretion in rats.

Animals↗
PubMed1989

Inhibition of sleep and benzodiazepine receptor binding by a beta-carboline derivative.

The effects of systemic injections of beta-carboline-3-carboxylate-t-butyl ester (beta-CCtB) were investigated with regard to normally occurring sleep and several measures of benzodiazepine receptor occupancy in rats. A dose of 30 mg/kg of beta-CCtB was found to have a long time-course of action as measured by an in vivo assay for benzodiazepine binding, with an 84% depletion of [3H]diazepam binding at one hour after the intraperitoneal injection. This dose of beta-CCtB was shown to delay sleep onset, decrease non-REM and total sleep in the first two hours after the injection, and to delay the appearance of REM sleep after the sleep onset. The dose- and time-dependence of the effects on sleep approximated the dose- and time-dependence of inhibitory effects of an IP injection of beta-CCtB on in vitro measures of benzodiazepine receptor affinity and number.

Animals↗
PubMed1989

Behavioral and electroencephalographic effects of the adenosine1 agonist, L-PIA.

The effects of N6-(L-2-phenylisopropyl)-adenosine (L-PIA), an A1 agonist, were measured on both spontaneous locomotor activity and electroencephalographic (EEG) measures of sleep in rats. L-PIA strongly inhibited motor activity at 100 micrograms/kg intraperitoneally (IP), a dose which had no statistically significant effects on EEG-defined sleep. A higher dose of L-PIA (200 micrograms/kg) increased the latency to sleep initiation and inhibited later REM sleep. These results demonstrate that L-PIA can produce a state of apparent behavioral quiescence in the presence of EEG-defined arousal.

Adenosine↗
PubMed1989

Longitudinal sleep EEG, temperature, and activity measurements across the menstrual cycle in patients with premenstrual depression and in age-matched controls.

After a 2-month evaluation period, eight women with moderate to severe premenstrual depression and eight age- and sex-matched controls underwent sleep electroencephalographic (EEG) and temperature recordings 2 nights a week over the course of one menstrual cycle. Overall, patients had more Stage 2 (%) sleep and less rapid eye movement (REM) sleep (% and minutes) than normal controls. Stage 3 sleep and number of intermittent awakenings varied with phases of the menstrual cycle. Temperature minima were earlier in patients compared with controls, but this difference was not statistically significant, and there was no significant effect of menstrual cycle phase on the timing of temperature minima. Wrist motor activity did not change during the menstrual cycle in patients or controls. Thus, in this sample of women with premenstrual depression, we did not find sleep EEG alterations similar to those reported in some patients with major depressive disorder. In light of the small number of subjects and the large individual variability, the absence of marked changes with the menstrual cycle may be a function of a Type II error.

Adult↗