Biomedical subjects
M A Demitrack
Publications and source records attributed to M A Demitrack.
Thyroid function in bulimia nervosa.
Bulimia nervosa is characterized by episodes of binge eating. Bulimic patients have diminished caloric requirements and reduced metabolic rate. Because thyroid function is an important modulator of metabolic rate, we sought to clarify conflicting reports concerning this parameter in bulimic patients. Thyroid indices were examined in 18 bulimics at admission and after 3 weeks of abstinence. Patients had thyroid indices in the normal range at admission but slightly diminished triiodothyronine (T3) compared with control subjects (n = 28). Significant declines in T3 and thyroxine and increases in thyrotropin were noted after 3 weeks of abstinence. At abstinence, T3 was positively correlated with caloric intake, protein, fat, and carbohydrate consumption and inversely correlated with percent ideal body weight. We hypothesize that binge-purge behavior may transiently increase thyroid indices and, consequently, metabolic rate in patients with bulimia nervosa. Furthermore, decreases in T3 following abstinence may be related to diminished caloric consumption or may reflect hypothalamic-pituitary dysregulation in these patients.
The impact of sexual and physical abuse on eating disordered and psychiatric symptoms: a comparison of eating disordered and psychiatric inpatients.
The authors compared rates of physical and sexual abuse in women with eating disorders (N = 102) and general psychiatric disorders (N = 49). Relationships between sexual abuse and severity of eating disordered and psychiatric symptoms were also examined. While high rates of sexual abuse were found in the eating disordered sample, these rates were not significantly higher than those found in the general psychiatric population. No relationship between a history of sexual abuse and severity of eating disordered symptoms was found. However, within the eating disordered group, sexually abuse subjects reported more severe psychiatric disturbances of an obsessive and phobic nature than nonabused subjects. These findings suggest that while sexually abusive experiences may be related to increased psychological distress, they do not serve to increase eating disordered symptomatology.
Relation of dissociative phenomena to levels of cerebrospinal fluid monoamine metabolites and beta-endorphin in patients with eating disorders: a pilot study.
Dissociation is made manifest by a failure to integrate thoughts, feelings, memories, and actions into a unified sense of consciousness. Although dissociation is presumed to be a special state of consciousness manifested by state-dependent memory and physiology, the psychobiology of dissociation is poorly understood. In this study, we examined cerebrospinal fluid levels of the major monoamine metabolites and beta-endorphin in patients with eating disorders (11 with anorexia nervosa, 16 with bulimia nervosa), while they were acutely ill. Dissociative capacity was measured using the Dissociative Experiences Scale (DES). We provide evidence that neurochemical changes in dopaminergic, serotonergic, and opioid systems may be associated with the clinical expression of dissociation in patients with eating disorders during the acute phase of their illness. These preliminary results are compatible with previous studies of neurochemical disturbances in the eating disorders and suggest that future work in dissociation should specifically include examination of these neurobiologic systems.
Effects of the glucocorticoid antagonist RU 486 on pituitary-adrenal function in patients with anorexia nervosa and healthy volunteers: enhancement of plasma ACTH and cortisol secretion in underweight patients.
To further explore whether the hypercortisolism of anorexia nervosa reflects an alteration in the set point for corticotropin-releasing hormone (CRH) secretion or is a manifestation of glucocorticoid resistance, we examined plasma ACTH and cortisol responses to the competitive glucocorticoid antagonist RU 486 (10 mg/kg, p.o. at 8.00 h) versus placebo (PBO) in 7 healthy female volunteers and 8 patients with DSM-III-R anorexia nervosa, all of whom were studied while underweight [64.3 +/- 2.1% average body weight (ABW), mean +/- SE] and 5 of whom were restudied longitudinally following refeeding (> or = 85% ABW, mean 87.4 +/- 0.4% ABW). Blood samples were obtained from 16.00 to 16.30 h and from 4.00 to 8.00 h following dosing. Underweight anorexics were significantly hypercortisolemic by 24 h urinary free cortisol excretion compared with controls (239 +/- 37 vs. 119 +/- 12 nmol/day, p < 0.01). Both controls and underweight anorexics had robust early morning (4.00-8.00 h) plasma cortisol responses to RU 486 (465 +/- 61 and 719 +/- 49 nmol/l) compared with PBO (370 +/- 52 and 451 +/- 31 nmol/l; p < 0.02 and p < 0.01, respectively). The underweight anorexics showed a significant mean early morning plasma ACTH response to RU compared with placebo (3.28 +/- 0.63 vs. 2.01 +/- 0.24 pmol/l, p < 0.05), while the controls showed a trend toward an increase in mean plasma ACTH after RU (3.11 +/- 0.36 pmol/l) compared with PBO (2.31 +/- 0.41 pmol/l, p < 0.13); plasma ACTH means were greater on the RU day than the placebo day at 20 of 25 sampling points (p < 0.001). However, the increment in ACTH on the RU day compared to the placebo day was greater in the underweight anorexics at the first 20 of 25 consecutive time points of the early morning sampling period (p < 0.001). Moreover, underweight anorexics showed a significant plasma ACTH and cortisol response to RU 486 at 16.00-16.30 h (8-8.5 h following administration), while the controls showed no significant response of plasma ACTH or cortisol at this time. When restudied following weight recovery, anorexic patients showed reductions in 24-hour urinary free cortisol excretion (to 191 +/- 40 nmol/day) which were no longer significantly elevated compared with control values.(ABSTRACT TRUNCATED AT 400 WORDS)
Plasma and cerebrospinal fluid monoamine metabolism in patients with chronic fatigue syndrome: preliminary findings.
The syndrome of chronic fatigue, feverishness, diffuse pains, and other constitutional complaints, often precipitated by an acute infectious illness and aggravated by physical and emotional stressors, has a lengthy history in the medical literature. The Centers for Disease Control (CDC) recently formulated a case definition, renaming the illness "chronic fatigue syndrome." Nevertheless, there remain few biological data that can validate the existence of this syndrome as distinct from a wide variety of other, largely psychiatric disorders, and little understanding of its pathogenesis. In the present study, basal plasma and cerebrospinal fluid levels of the monoamine metabolites, 3-methoxy-4-hydroxyphenylglycol (MHPG), 5-hydroxyindoleacetic acid (5-HIAA), and homovanillic acid (HVA) were determined in 19 patients meeting CDC research case criteria for chronic fatigue syndrome and in 17 normal individuals. Patients with chronic fatigue syndrome showed a significant reduction in basal plasma levels of MHPG and a significant increase in basal plasma levels of 5-HIAA. Although the functional significance of these findings has not been definitively elucidated, they are compatible with the clinical presentation of a syndrome associated with chronic lethargy and fatigue, and with evidence of persistent immune stimulation, and lend support to the idea that chronic fatigue syndrome represents a clinical entity with potential biological specificity.
Depression after cyproheptadine: MAO treatment.
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Taste responses and preferences for sweet high-fat foods: evidence for opioid involvement.
Preferences and cravings for sweet high-fat foods observed among obese and bulimic patients may involve the endogenous opioid peptide system. The opioid antagonist naloxone, opioid agonist butorphanol, and saline placebo were administered by intravenous infusion to 14 female binge eaters and 12 normal-weight controls. Eight of the binge eaters were obese. During infusion, the subjects tasted 20 sugar/fat mixtures and were allowed to select and consume snack foods of varying sugar and fat content. Naloxone reduced taste preferences relative to baseline in both binge eaters and controls. Total caloric intake from snacks was significantly reduced by naloxone in binge eaters but not in controls. This reduction was most pronounced for sweet high-fat foods such as cookies or chocolate. No consistent effects on taste preferences or food intakes were observed with butorphanol. Endogenous opioid peptides may be involved in mediating taste responses and preferences for palatable foods, notably those rich in sugar and fat.
Quinolinic acid and kynurenine pathway metabolism in inflammatory and non-inflammatory neurological disease.
Neurological dysfunction, seizures and brain atrophy occur in a broad spectrum of acute and chronic neurological diseases. In certain instances, over-stimulation of N-methyl-D-aspartate receptors has been implicated. Quinolinic acid (QUIN) is an endogenous N-methyl-D-aspartate receptor agonist synthesized from L-tryptophan via the kynurenine pathway and thereby has the potential of mediating N-methyl-D-aspartate neuronal damage and dysfunction. Conversely, the related metabolite, kynurenic acid, is an antagonist of N-methyl-D-aspartate receptors and could modulate the neurotoxic effects of QUIN as well as disrupt excitatory amino acid neurotransmission. In the present study, markedly increased concentrations of QUIN were found in both lumbar cerebrospinal fluid (CSF) and post-mortem brain tissue of patients with inflammatory diseases (bacterial, viral, fungal and parasitic infections, meningitis, autoimmune diseases and septicaemia) independent of breakdown of the blood-brain barrier. The concentrations of kynurenic acid were also increased, but generally to a lesser degree than the increases in QUIN. In contrast, no increases in CSF QUIN were found in chronic neurodegenerative disorders, depression or myoclonic seizure disorders, while CSF kynurenic acid concentrations were significantly lower in Huntington's disease and Alzheimer's disease. In inflammatory disease patients, proportional increases in CSF L-kynurenine and reduced L-tryptophan accompanied the increases in CSF QUIN and kynurenic acid. These responses are consistent with induction of indoleamine-2,3-dioxygenase, the first enzyme of the kynurenine pathway which converts L-tryptophan to kynurenic acid and QUIN. Indeed, increases in both indoleamine-2,3-dioxygenase activity and QUIN concentrations were observed in the cerebral cortex of macaques infected with retrovirus, particularly those with local inflammatory lesions. Correlations between CSF QUIN, kynurenic acid and L-kynurenine with markers of immune stimulation (neopterin, white blood cell counts and IgG levels) indicate a relationship between accelerated kynurenine pathway metabolism and the degree of intracerebral immune stimulation. We conclude that inflammatory diseases are associated with accumulation of QUIN, kynurenic acid and L-kynurenine within the central nervous system, but that the available data do not support a role for QUIN in the aetiology of Huntington's disease or Alzheimer's disease. In conjunction with our previous reports that CSF QUIN concentrations are correlated to objective measures of neuropsychological deficits in HIV-1-infected patients, we hypothesize that QUIN and kynurenic acid are mediators of neuronal dysfunction and nerve cell death in inflammatory diseases. Therefore, strategies to attenuate the neurological effects of kynurenine pathway metabolites or attenuate the rate of their synthesis offer new approaches to therapy.
Regulation of appetite and cholecystokinin secretion in anorexia nervosa.
Six patients with anorexia nervosa, the same patients after weight normalization, and six healthy control subjects had similar fasting and postprandial plasma cholecystokinin concentrations. These data do not support the hypothesis that low levels of hunger and food intake in anorexic patients reflect hypersecretion of this endogenous hormone, which is thought to inhibit hunger, promote satiety, and reduce feeding.
Plasma and cerebrospinal fluid measures of arginine vasopressin secretion in patients with bulimia nervosa and in healthy subjects.
Bulimia nervosa is a psychiatric syndrome associated with intense hunger, deficient satiety mechanisms, an obsessional preoccupation with the adverse consequences of eating, ritualistic binge eating, and subsequent purging to forestall the effects of the binge. The morbidity of this illness reflects both the psychological suffering associated with a life organized around pathological eating behaviors, as well as medical complications such as fluid and electrolyte imbalances that occur largely as a result of purging and laxative abuse. We report here a study of the osmoregulation of plasma arginine vasopressin secretion and of vasopressin levels in the cerebrospinal fluid. This study was undertaken because vasopressin not only functions as the antidiuretic hormone, and thus as a principal modulator of fluid and electrolyte balance, but also because, in animals, centrally directed vasopressin delays the extinction of behaviors acquired during aversive conditioning. Thirteen normal-weight female patients with bulimia nervosa were studied after at least 1 month of nutritional stabilization and supervised abstinence from binge eating and purging. Plasma vasopressin, plasma sodium, and subjective thirst were measured serially before and during a 2-h infusion of 3% hypertonic saline (0.1 ml/kg min). In addition, cerebrospinal fluid was obtained by lumbar puncture upon admission and at 1 week before hypertonic saline infusion in 11 of these patients and in an additional 11 female patients who did not participate in the hypertonic infusion study. Fifteen healthy normal weight individuals (4 female, 11 male) served as controls for the hypertonic saline infusion and a separate group of 11 healthy normal weight female controls underwent puncture. Compared to controls, bulimic subjects showed a significant reduction in the plasma vasopressin response to hypertonic saline; in 12/13, plasma vasopressin correlated closely with plasma sodium, whereas in one patient vasopressin fluctuated erratically, with no relation to plasma sodium. Cerebrospinal fluid vasopressin levels were significantly higher in patients, and correlated positively with basal thirst level, which was enhanced in bulimics. Compared to controls, patients showed significant polyuria. We conclude that patients with bulimia nervosa have abnormal levels of vasopressin in their plasma and cerebrospinal fluid during abstinence from binge eating and purging. The disturbance in osmoregulation may aggravate the maintenance of adequate fluid volume in these patients, while the increase in centrally directed vasopressin may have relevance to their obsessional preoccupation with the aversive consequences of eating and weight gain.
Chronic fatigue syndrome: the need for an integrative approach.
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Possible bupropion precipitation of mania and a mixed affective state.
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Evidence for impaired activation of the hypothalamic-pituitary-adrenal axis in patients with chronic fatigue syndrome.
Chronic fatigue syndrome is characterized by persistent or relapsing debilitating fatigue for at least 6 months in the absence of a medical diagnosis that would explain the clinical presentation. Because primary glucocorticoid deficiency states and affective disorders putatively associated with a deficiency of the arousal-producing neuropeptide CRH can be associated with similar symptoms, we report here a study of the functional integrity of the various components of the hypothalamic-pituitary-adrenal axis in patients meeting research case criteria for chronic fatigue syndrome. Thirty patients and 72 normal volunteers were studied. Basal activity of the hypothalamic-pituitary-adrenal axis was estimated by determinations of 24-h urinary free cortisol-excretion, evening basal plasma total and free cortisol concentrations, and the cortisol binding globulin-binding capacity. The adrenal cortex was evaluated indirectly by cortisol responses during ovine CRH (oCRH) stimulation testing and directly by cortisol responses to graded submaximal doses of ACTH. Plasma ACTH and cortisol responses to oCRH were employed as a direct measure of the functional integrity of the pituitary corticotroph cell. Central CRH secretion was assessed by measuring its level in cerebrospinal fluid. Compared to normal subjects, patients demonstrated significantly reduced basal evening glucocorticoid levels (89.0 +/- 8.7 vs. 148.4 +/- 20.3 nmol/L; P less than 0.01) and low 24-h urinary free cortisol excretion (122.7 +/- 8.9 vs. 203.1 +/- 10.7 nmol/24 h; P less than 0.0002), but elevated basal evening ACTH concentrations. There was increased adrenocortical sensitivity to ACTH, but a reduced maximal response [F(3.26, 65.16) = 5.50; P = 0.0015). Patients showed attenuated net integrated ACTH responses to oCRH (128.0 +/- 26.4 vs. 225.4 +/- 34.5 pmol/L.min, P less than 0.04). Cerebrospinal fluid CRH levels in patients were no different from control values (8.4 +/- 0.6 vs. 7.7 +/- 0.5 pmol/L; P = NS). Although we cannot definitively account for the etiology of the mild glucocorticoid deficiency seen in chronic fatigue syndrome patients, the enhanced adrenocortical sensitivity to exogenous ACTH and blunted ACTH responses to oCRH are incompatible with a primary adrenal insufficiency. A pituitary source is also unlikely, since basal evening plasma ACTH concentrations were elevated. Hence, the data are most compatible with a mild central adrenal insufficiency secondary to either a deficiency of CRH or some other central stimulus to the pituitary-adrenal axis. Whether a mild glucocorticoid deficiency or a putative deficiency of an arousal-producing neuropeptide such as CRH is related to the clinical symptomatology of the chronic fatigue syndrome remains to be determined.
Pineal-adrenal interactions: the effect of acute pharmacological blockade of nocturnal melatonin secretion.
The pineal gland is a complex neuroendocrine organ which is under photoneuroendocrine control. Previous studies in animals and humans have suggested reciprocal variations in pineal melatonin biosynthesis and adrenal glucocorticoid output; it remains unclear, however, whether a causal relationship exists between these two systems. To address this question, we examined the overnight secretory activity of the hypothalamic-pituitary-adrenal (HPA) axis in conjunction with acute pharmacological suppression of pineal melatonin biosynthesis in 11 healthy volunteers. Results of the current study are consistent with the hypothesis that melatonin does not function as a tonic inhibitor of the HPA axis on an acute basis.
CSF oxytocin in anorexia nervosa and bulimia nervosa: clinical and pathophysiologic considerations.
Oxytocin is a hypothalamic neuropeptide with both centrally and peripherally directed pathways. Data from experimental animals indicate that oxytocin impairs consolidation of aversively conditioned behaviors and is released after feeding or experimental gastric distension. The authors report that the mean CSF oxytocin level of five underweight women with restricting anorexia, but not 12 underweight bulimic anorexic women or 35 normal-weight women with bulimia nervosa, was significantly lower than the level of 11 control subjects. Restricting anorexic patients' low CSF oxytocin levels may reflect their persistently low food intake, and this behavior may exacerbate their tendency for perseverative preoccupation with adverse consequences of food intake.
Relation of clinical variables to dissociative phenomena in eating disorders.
In this study 30 female patients with eating disorders were compared with 30 age-matched normal female subjects. The patients demonstrated significantly higher levels of dissociative psychopathology than the comparison subjects. Furthermore, the presence of severe dissociative experience appeared to be specifically related to a propensity for self-mutilation and suicidal behavior. These findings are discussed in light of recent data which suggest that neurochemical systems shown to be abnormal in patients with eating disorders may be key pathophysiologic substrates for dissociative experience.
Corticotropin-releasing hormone: from endocrinology to psychobiology.
Corticotropin-releasing hormone (CRH) is a brain neuropeptide which coordinates the endocrine, autonomic and behavioral responses to stress. We review the abnormal response to exogenous CRH in various psychiatric syndromes, including major depression and anorexia nervosa. We also contrast pituitary responses to CRH in patients with depression versus Cushing's disease. We hypothesize that CRH may play a role in the pathogenesis of various psychiatric syndromes which are characterized during their course by the symptom of depression.