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Biomedical subjects

B H Natelson

Publications and source records attributed to B H Natelson.

At least 73 records · Page 4Linked to original sources
PubMed1996

Selective impairment of auditory processing in chronic fatigue syndrome: a comparison with multiple sclerosis and healthy controls.

The most consistent deficit observed in individuals with Chronic Fatigue Syndrome has been in efficiency of information processing. To examine the possibility of a modality-specific impairment, the present study examined subjects with Chronic Fatigue Syndrome, multiple sclerosis, and healthy controls on an auditory-versus visual-paced serial-addition test. 20 subjects with Chronic Fatigue Syndrome, 20 subjects with clinically definite Multiple Sclerosis, and 20 sedentary healthy controls were compared. One-half of the subjects in each group were administered the Paced Auditory Serial Addition Test and the other half were administered the Paced Visual Serial Addition Test. The group with Chronic Fatigue Syndrome was differentially impaired on the auditory relative to the visual processing task. The group with Multiple Sclerosis was equally impaired on both versions of the task. The results are discussed within the framework of Baddeley's model of working memory.

Adult↗
PubMed1996

The role of stressor intensity in influencing the course of heart disease in cardiomyopathic hamsters.

Our earlier work showed that stress had progressively more serious consequences in a hamster model of congestive heart failure as the magnitude of heart failure worsened. Based on that study, we hypothesized that the intensity of the stressor used might play an important part in determining this outcome as well as in influencing coronary reactivity to arginine vasopressin (AVP). Cardiomyopathic (2.5, 6.5, and 10 months) hamsters (CMHs) were stressed with a 2-hr period of supine immobilization for five consecutive days. Stressor intensity was increased by exposing the hamsters to progressively longer periods at 4 degrees C: the low stress group was never put in the cold; the moderate stress group was exposed to cold for 1 hr, and the high stress group for 2 hr. CMHs were anesthetized and sacrificed 5 days after stress, and their hearts were perfused using a modified Langendorff system. Maximum +/- dP/dt, developed pressure, ventricular relaxation time, (T), and coronary vascular resistance (CVR) were recorded, and CVR was also measured following coronary infusion of AVP. Stressor intensity had no effect on cardiac mechanics in 2.5-month CMHs. In 6.5-month CMHs, only the high-intensity stressor impaired ventricular mechanics (decreased maximum +/- dP/dt and developed pressure, increased T; P < 0.05), while low and moderate stress produced no effects. In 10-month CMHs, stress at all intensities exacerbated ventricular dysfunction (decreased maximum +/- dP/dt and developed pressure; P < 0.05). These results support our first hypothesis that stressor intensity interacts multiplicatively with severity of the underlying disease to influence the course of heart failure. However, our second hypothesis was not supported, because stress-regardless of intensity-affected reactivity of the coronary vasculature to AVP only in 2.5-month CMHs. A further test of the relation of stressor intensity and coronary vascular reactivity requires study of additional groups of CMHs during the period of their disease characterized by coronary vasospasm.

Analysis of Variance↗
PubMed1995

Delayed startle sensitization distinguishes rats exposed to one or three stress sessions: further evidence toward an animal model of PTSD.

Posttraumatic stress disorder (PTSD) may occur in humans exposed chronically to stressors or after a single exposure to a traumatic event. A distinguishing feature of patients with PTSD is an exaggerated startle response, evident long after the traumatic event. We have observed similar abnormalities in our animal model of a chronic stress state. Rats exposed to 3 days (3DS) of our stress regimen (2-hr sessions of 40, 2 mA tailshocks) have exhibited a consistent pattern of persistent physiological and behavioral abnormalities including an exaggerated startle response several days after stressor cessation. In contrast, rats exposed to a single stress session (1DS) have exhibited many, but not all, of the persistent abnormalities displayed by 3DS rats. The present experiment compared the startle responding of 3DS and 1DS rats 4, 7, and 10 days after stressor cessation. Consistent with previous work, stressed rats exhibited elevated basal plasma corticosterone (CORT) levels the first day poststressor. These CORT levels were sensitive to the number of stressor exposures with higher CORT levels in 3DS rats than in 1DS rats. As for startle responding, the 1DS rats exhibited an exaggerated startle response 7 days poststressor, whereas startle sensitization was apparent 10 days poststressor in 3DS rats. Thus, the appearance of an exaggerated startle response after stressor cessation appears to be related to the number of stress session exposures. These animal models, the 3DS and 1DS rats, may be useful to gain insight into the neurobehavioral changes associated with PTSD.

Animals↗
PubMed1995

Gait abnormalities in chronic fatigue syndrome.

To evaluate our clinical impression that patients with the chronic fatigue syndrome (CFS) did not walk normally, we assessed gait kinematics at slow walking speeds (i.e., 0.45, 0.89 and 1.34 m/sec) and 30 m run time speeds on CFS patients and on a comparison group of sedentary controls. Run time was significantly slower for CFS than control subjects (p < 0.001). There was a significant interaction (p < 0.01) between group and speed for maximum hip angle during stance and swing phase with hip angle being significantly larger at 1.34 m/sec for CFS than controls subjects for both cases (p < 0.05). Knee flexion during stance and swing phases was significantly larger for controls than CFS subjects at 0.45 m/sec (p < 0.01). Ratio of stride length divided by leg length was significantly larger for the control subjects than for the CFS subjects with differences occurring at 0.45 and 0.89 m/sec (p < 0.01) but not 1.34 m/sec. The data indicate that CFS patients have gait abnormalities when compared to sedentary controls. These could be due to balance problems, muscle weakness, or central nervous system dysfunction; deciding which will require further research. Evaluation of gait may be a useful tool to measure outcome following therapeutic interventions.

Adult↗
PubMed1995

Effects of exposure to stressors of varying predictability on adrenal function in rats.

For 5 days, rats were exposed to shocks that were signalled by a light 0, 33, 66, or 100% of the time. Basal hormone levels and responses to a light-shock pair were measured daily. Greater predictability was associated with higher basal plasma corticosterone and norepinephrine levels indicative of chronic stress. Habituation of the corticosterone response was also less in the groups with greater predictability. However, predictability did not affect plasma prolactin or epinephrine responses. Because the endocrine systems responded differently, it is unlikely that the changes were due to a unitary process. Greater predictability appeared to be more stressful in this paradigm. Both associative and nonassociative factors have major roles in determining the hormonal responses to repeated presentation of stressors.

Adrenal Glands↗
PubMed1995

Reducing heterogeneity in chronic fatigue syndrome: a comparison with depression and multiple sclerosis.

Chronic fatigue syndrome (CFS) is a heterogeneous illness characterized by a high prevalence of psychiatric problems. We reasoned that we could reduce heterogeneity by excluding patients with psychiatric problems preceding CFS. We compared the functional status, mood, fatigue level, and psychiatric status of this more homogeneous group of CFS patients with the same parameters in patients with mild multiple sclerosis and in patients with major depression or dysthymia. Patients with CFS and those with multiple sclerosis were similar in terms of level of anger, severity of depression, level of anxiety, and frequency of current psychiatric diagnoses. Patients with CFS resembled depressed patients in having impaired vigor and experiencing substantial fatigue and confusion--problems constituting part of the case definition of CFS. The group with CFS was not psychologically vulnerable before the development of this condition and maintained adequate networks of social support despite disabling illness. Stratification to exclude patients with prior psychiatric disease and those with mild CFS allowed us to define a group of patients with CFS who more resembled patients with mild MS than patients with major depression or dysthymia and thus were more likely to have illness with an infectious or immunologic cause. Use of such a stratification strategy should prove important in testing of the viral/immunologic hypothesis of the etiology of CFS.

Adolescent↗
PubMed1995

Frequency of deviant immunological test values in chronic fatigue syndrome patients.

Of 11 immunological tests done on chronic fatigue syndrome patients and on fatigued controls, 3 tests (protein A binding, Raji cell, or C3 or C4 [deviant values in either complement component were counted as positive]) with deviant results discriminated best among the groups. Other tests, including immunoglobulin G subclasses, complement component CH50, interleukin-2, and anticardiolipin antibodies, did not discriminate well among the groups.

Fatigue Syndrome, Chronic↗
PubMed1995

Neuropsychological impairments in chronic fatigue syndrome, multiple sclerosis, and depression.

To examine the degree and nature of cognitive impairments in chronic fatigue syndrome, a comprehensive neuropsychological battery was given to patients with chronic fatigue syndrome, multiple sclerosis, depressed patients, and healthy controls. The battery included tests of attention and concentration, information processing speed, verbal and visual memory, intellectual ability, and concept formation. Measures of depression and anxiety were also obtained. The chronic fatigue syndrome group did not differ from the depressed group in overall neuropsychological performance, but differed from the multiple sclerosis and control groups. The most significant impairment was in information processing speed in the chronic fatigue syndrome group. Depression and anxiety were not related to neuropsychological performance. The influence of reduced information processing on other areas of cognition is discussed.

Adult↗
PubMed1995

Stress triggers different pathophysiological mechanisms in younger and older cardiomyopathic hamsters.

OBJECTIVES: Because cardiomyopathic hamsters (CMHs) in the lesion-forming period of their disease are more susceptible to the lethal effects of stress than older CMHs, we tested the hypothesis that different pathophysiological effects of stress may occur: coronary vasospasm in younger CMHs and congestive heart failure in older ones. METHODS: CMHs aged 2.5 and 6.5 months were stressed with 2 h supine cold immobilization for 5 consecutive days. Three, 5 and 7 days after stress, the hearts were excised and perfused using a modified Langendorff system. Maximum +/- dP/dt, developed pressure, ventricular relaxation time (Tau) and coronary vascular resistance (CVR) were recorded and CVR was also measured following coronary infusion of arginine vasopressin (AVP). RESULTS: Stress produced ventricular dysfunction (decreased maximum +/- dP/dt, developed pressure, and increased Tau) in older CMHs (P < 0.05) but not in younger CMHs. Baseline CVR in younger CMHs was significantly higher than in older CMHs (P < 0.01) and AVP infusion produced a bigger increase in CVR in younger stressed CMHs than in either younger nonstressed or older stressed CMHs (P < 0.05). CONCLUSION: The younger CMH heart exhibits greater resting vascular tone and stress produces coronary vasoconstriction that is consistent with coronary spasm. In contrast, the older CMH experiences a decrease in cardiac function which remains 7 days after stress and indicates an exacerbation of CHF from the mild form existing prior to stress. The lethal effects of stress may occur because of the activation of different pathological processes in younger and older CMHs.

Age Factors↗
PubMed1994

High titers of anti-Epstein-Barr virus DNA polymerase are found in patients with severe fatiguing illness.

Forty-one patients with chronic fatigue syndrome (CFS), 76 healthy controls matched with the patient group for age range, sex, race, and socioeconomic class, and 22 symptomatic patients with seasonal affective disorder (SAD) had serum sampled for antibodies against 2 Epstein-Barr virus (EBV) replicating enzymes. Abnormal titers of antibodies were found twice as often in CFS patients as controls (34.1% vs. 17.1%), with SAD patients having an intermediate frequency (27.3%). Stratifying for disease severity sharpened the differences considerably, with the sicker CFS and SAD patients having 52% and 50% abnormal tests, respectively; more mildly afflicted CFS and SAD patients had a frequency of abnormal tests in the normal range. Antibodies to EBV DNA polymerase (DNAP) were the more sensitive of the two tests in that they were positive in all cases but one. These findings suggest that antibodies against EBV DNAP may be a useful marker in delineating a subset of patients with severe fatiguing illness for appropriate treatment trials and for monitoring their outcomes.

Adult↗
PubMed1994

A comparison of the effects of repeated stressor exposures and corticosterone injections on plasma cholesterol, thyroid hormones and corticosterone levels in rats.

Persistently elevated serum cholesterol (CHOL) levels have been observed in rats given repeated stressor exposures and fed a normal laboratory diet. To determine the relative contribution of persistent hormone changes in the hypothalamic-pituitary-adrenal (HPAA) and thyroid axes to persistent stress-induced CHOL elevations, the present experiment assessed the contribution of persistently elevated corticosterone (CORT) from both endogenous and exogenous sources. Groups of rats were exposed for 7 days to stress sessions (7DS; 40, 2mA tailshocks given over 2 h each day), CORT injections (CI; 10 mg/l ml vehicle/day) or vehicle injections (VI; sesame oil), or served as noninjected, undisturbed controls (CON). In addition, another group of rats were adrenalectomized (ADX). Basal blood samples were drawn for CORT determination on the 1st, 4th, 7th, and 8th experimental days. The blood samples from the 8th day, 22 h after the last stress session or injection were also assayed for CHOL, T3 and T4. The basal CORT levels of both 7DS and CI rats were elevated on the 4th and 7th experimental days. Contrary to expectations, 7 daily exposures to the stress regimen did not persistently alter plasma CORT, CHOL, T3 or T4 levels. The CI rats did exhibit elevated CORT on the 8th experimental day which was accompanied by elevated CHOL levels and suppressed T4 levels. However, elevated CHOL levels were also found in ADX rats and these elevations were accompanied by suppressed T3 levels. These data suggest that persistent CORT elevations are not necessary for persistent plasma CHOL elevations after stressor exposure, but further research is necessary to clarify the role of the HPAA and thyroid axes in stress-induced plasma CHOL elevations.

Adrenalectomy↗
PubMed1994

Repeated stress persistently elevates morning, but not evening, plasma corticosterone levels in male rats.

Repeated exposures to a stressor in our rat model of a chronic stress state cause elevated plasma corticosterone levels in the morning for several days after the last stressor. However, plasma corticosterone levels are normally characterized by a circadian rhythm with low levels for much of the morning and higher levels near the onset of darkness. The current experiment examined the question of whether the elevated morning levels after stressor exposures were accompanied by other changes in this circadian rhythm. Male rats were given restraint-shock stressor sessions for 0, 1, or 3 days, after which plasma samples were collected for 3 days at 0900 h and at three other times around the circadian peak (1400, 1800, and 2200 h). Plasma corticosterone levels at 0900 h were elevated for the first 2 days after three stressor exposures and for 1 day after a single stressor exposure compared to those in nonstressed controls. However, levels at 1400, 1800, and 2200 h were not different in stressed and control rats on the first 2 days after stressor exposures. In addition, the amplitude of the corticosterone rhythm was suppressed after three stressor exposures, but not after one. This decrease in amplitude was mostly due to increased morning levels, inasmuch as the evening levels were similar in stressed rats and controls. Because the hypothalamic-pituitary-adrenal axis is more sensitive to glucocorticoid feedback in the morning, our data suggest that the mechanisms mediating feedback at this time of day may be disrupted by repeated stressor exposures.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Persistent stress-induced sensitization of adrenocortical and startle responses.

We assessed the functional adrenocortical and behavioral state of rats previously exposed to repeated stressor presentations. In Experiment 1, the whole-body startle response to threshold (91 dB) and suprathreshold (96 dB) stimuli was assessed in rats given 3 daily sessions (3DS) of 40, 2-mA tailshocks. The 3DS rats showed an exaggerated startle response to the threshold auditory stimulus 4 days poststressor compared to nonshocked controls (CON). An exaggerated startle response in stressed rats was not evident either 1 day or 10 days poststressor. In Experiment 2, adrenocortical sensitization and behavioral reactivity were assessed in rats exposed to 1 day (1DS) or 3 days of our stress regimen. Stressed rats exhibited elevated basal plasma corticosterone (CORT) levels 1 day poststressor which recovered by 9 days poststressor. Stressed rats also exhibited suppressed open-field activity 4 days poststressor. On the 10th day poststressor, rats were exposed to a single tailshock. The 1DS and 3DS rats showed both a sensitized and prolonged CORT response to stressor reexposure compared to control rats which received only the single tailshock. In addition, on the 11th day poststressor 3DS rats exhibited a moderate recapitulation of the elevated basal CORT levels seen after the initial stressor exposures. Thus, exposure to our stress regimen produces a chronic stress state in rats characterized by persistent behavioral and adrenocortical sensitization, as well as suppressed open-field activity and elevated basal CORT levels. Rats exhibiting a chronic stress state may be appropriate as a model for the study of stress-related psychophysiological illnesses, such as posttraumatic stress disorder.

Acoustic Stimulation↗
PubMed1994

Cognitive functioning of patients with chronic fatigue syndrome.

Neuropsychological problems are a distressing and frequent component of the symptom complex associated with chronic fatigue syndrome. Objective assessment of these difficulties is essential to understanding the nature of this illness. Results of the studies discussed in this paper suggest that impaired information processing, rather than primary memory dysfunction, may be at the root of the cognitive problems that afflict so many patients with CFS.

Cognition↗
PubMed1994

Enhanced coronary vasoconstriction in the Syrian myopathic hamster supports the microvascular spasm hypothesis.

OBJECTIVE: The heart of the young Syrian cardiomyopathic hamster (CMH) displays discrete patches of active myocytolytic necrosis and it has been hypothesised that these lesions are triggered by arteriolar spasm. Accordingly, we tested the theory that the coronary vasoconstrictor response to arginine vasopressin (AVP) infusion is more vigorous in the actively necrotising young (2-3 month old) CMH than in age matched normal hamsters, 5-6 month old CMHs in the histologically quiescent phase of the disease, or 5-6 month old normal hamsters. METHODS: An isovolumetric isolated heart preparation was used in which the coronary arteries were perfused with Krebs-Henseleit buffer at constant flow by a syringe pump. Coronary vascular resistance was determined by the ratio of measured perfusion pressure to flow rate during extended diastoles. RESULTS: There were no significant differences in baseline coronary vascular resistance among the four groups. The increase in resistance with AVP infusion (0.54 pressor units.min-1) was significantly greater (p < 0.01) in the young CMH [6.66(SEM 4.75) mm Hg.ml-1.min-1] than in the old CMH [1.66(0.78)], the young normal [1.10(1.07)], and the old normal [2.72(1.86)] groups. CONCLUSIONS: There is increased vasoconstrictive responsiveness in the young CMH coronary vasculature. The results suggest a broader coronary abnormality in this myopathic model and are consistent with the microvascular spasm hypothesis of myocytolytic lesion formation.

Aging↗
PubMed1993

A controlled study of brain magnetic resonance imaging in patients with the chronic fatigue syndrome.

Two neuroradiologists compared the brain MR scans of 52 patients with the CDC criteria for the chronic fatigue syndrome (CFS) with those of 52 age and sex matched controls who had undergone imaging because of histories of head trauma or headache. CFS patients had significantly more abnormal scans than controls--27% vs 2%. Abnormalities seen were foci of increased white matter T2 signal in 9 CFS patients and one control and ventricular or sulcal enlargement in 5 CFS patients. Follow up of patients with subcortical signal hyperintensities revealed 3 who had symptoms suggestive of other known medical causes of what appeared to be CFS. The data indicate that some CFS patients have some organic problem manifesting itself on neuroimaging. But, finding MR abnormalities should warn the physician that the patient's symptoms may be secondary to some other medical illness and not simply primary CFS.

Adolescent↗
PubMed1993

Information processing efficiency in chronic fatigue syndrome and multiple sclerosis.

OBJECTIVE: To compare the cognitive performance of subjects with chronic fatigue syndrome (CFS), multiple sclerosis (MS), and healthy controls. All subjects were matched for age, education, and verbal intelligence, as previous neuropsychological studies of CFS had not used appropriate control groups. DESIGN: Case-control design. All subjects were given a neuropsychological battery and the test scores were compared among the groups. SETTING: Subjects with CFS and subjects with MS were recruited from private and institutional practice and from the community. Healthy subjects were recruited from the community. PATIENTS/OTHER PARTICIPANTS: Twelve subjects (all female) with CFS participated in the study. Chronic fatigue syndrome was diagnosed in these patients in accordance with the requirements outlined by the Centers for Disease Control as modified subsequently to not exclude patients with concurrent depression and/or anxiety. All subjects with CFS were referred for a neuropsychological examination to assess persistent cognitive complaints. Eleven subjects (10 female, one male) with the diagnosis of clinically stable MS were chosen from clinics and the community because of complaints of mild to moderate cognitive impairment. The subjects with MS and 11 healthy volunteers (10 female, one male) were matched to the group with CFS by age, education, and estimated verbal intelligence (based on the Vocabulary subtest of the Wechsler Adult Intelligence Scale-Revised). The subjects with MS had a mean Kurtzke Expanded Disability Status Scale score of 4.95 (SD, 1.95; range, 2.0 to 7.5). As a result of the matching procedure, there were no differences among the three groups in age (F[2,31] = 0.32), education (F[2,31] = 0.80), and verbal intelligence (F[2,31] = 0.31). INTERVENTIONS: None. MAIN OUTCOME MEASURES: These measures included the Beck Depression Inventory (BDI), the Paced Auditory Serial Addition Test (PASAT), Digit Span Test, and the Similarities Test of Verbal Abstract Reasoning. RESULTS: The mean number of correctly identified responses collapsed across the four PASAT trials was significantly different across groups (F[2,31] = 4.03; P < .05). While the CFS and MS groups did not differ from each other, subjects with CFS (SEM, 124.2 +/- 6.4) and subjects with MS (SEM, 112.9 +/- 10.9) scored significantly below controls (SEM, 146.4 +/- 6.4) (Fisher's Protected Least Significant Difference test; P < .05). There were significant differences among the three groups on mean Digit Span Test performance (F[2,31] = 5.5; P < .01). While the CFS and MS group did not differ significantly from each other, only the CFS group was significantly lower than control (Fisher's Protected Least Significant Difference test; P < .05). Mean performance on the Similarities test did not differ among the three groups (F = 0.58). In addition, there were significant differences among the three groups in mean BDI scores (F[2,31] = 7.6; P < .01). The CFS and MS groups did not differ significantly from each other, and both groups showed a statistically significantly elevated mean BDI score relative to the control group (Fisher's Protected Least Significant Difference test; P < .05). No significant correlations were found between BDI scores and PASAT total scores (CFS, r = -.21; MS, r = .13; control, r = .27), or between BDI and Digit Span Test (CFS, r = -.32; MS, r = -.40; control, r = -.19). Results of the PASAT and Digit Span Test were significantly correlated in the CFS group (r = .71; P < .01), but not in the MS (r = .06) or control groups (r = .49). CONCLUSIONS: These results indicate that subjects with CSF and subjects with MS show significant impairment on a test of complex concentration when compared with appropriate controls. The data suggest that subjects with CFS and subjects with MS have difficulty on tasks that require the simultaneous processing of complex cognitive information. Selective impairment in information processing efficiency may lie at the

Adult↗