Immunisation of common marmosets with vaccinia virus expressing Epstein-Barr virus (EBV) gp340 and challenge with EBV

Epstein-Barr virus (EBV) is the cause of infectious mononucleosis and is associated with a variety of life-threatening diseases in humans. Therefore the development of an effective vaccine is an important objective. Many of the initial studies of vaccine efficacy analyse the ability of vaccine preparations to prevent the induction of lymphomas in cottontop tamarins by the B95-8 strain of EBV. We used a vaccinia virus recombinant expressing gp340, vMA1, tested previously in the cotton-top tamarin, to evaluate a common marmoset model in which the challenge virus, M81, resembles more closely the wild-type strains of EBV in the general population than does the standard B95-8 strain. We characterised the M81 strain of EBV with respect to the sequence of its gp340/220 gene and in regard to the presence of a region deleted in B95-8. Replication of the challenge virus in the group vaccinated with vMA1 was decreased when compared to control groups.

Effect of very delayed repair of congenital diaphragmatic hernia on survival and extracorporeal life support use

BACKGROUND

Since November 1992, operative repair in neonates with congenital diaphragmatic hernia (CDH) at this institution was delayed until respiratory insufficiency had resolved.

METHODS

A retrospective analysis was performed (n = 33) comparing delayed repair with our previously reported institutional experience with immediate repair from January 1988 to October 1992 (n = 66). Infants with severe genetic defects or moribund conditions or who were premature were not considered candidates for repair or extracorporeal life support (ECLS), but they were included in the survival analysis. Survival was defined as hospital discharge. Data were compared with an independent t test or Pearson chi-squared test.

RESULTS

Mean age at repair was 8.9 +/- 4.5 days (range, 3 to 20 days). Eleven infants in the study group were placed on ECLS (33% versus 68% in the comparison group; p = 0.001). Six of these infants survived (55% versus 58% in the comparison group; p = 0.846). Of these survivors, one patient was repaired while on ECLS, and the remainder underwent repair after decannulation from ECLS. All 20 of the remaining candidates for repair survived without need for ECLS. Overall survival was 79% versus 56% in the comparison group (p = 0.027).

CONCLUSIONS

Our current data suggest that very delayed repair of newborns with CDHs is associated with an increase in the overall survival and a decrease in the use of ECLS when compared with previous experience at this institution.

Genetic factors affecting the consistency and magnitude of changes in plasma cholesterol in response to dietary challenge

We examined the role of common genetic variation in determining the consistency and magnitude of change in plasma total cholesterol (TC) levels in response to two separate changes from a high-saturated (SFA) to a low-saturated/high-polyunsaturated-fat (PUFA) diet, in a group of free-living healthy men and women. Consistent responders were defined as those whose mean difference in the change in TC was within one SD of the mean for all participants, and the remainder were defined as variable responders. DNA was obtained from 55 individuals and genotype determined at the apolipoprotein (apo) B locus (signal peptide, SP), apoCIII (C1100-T) and lipoprotein lipase (LPL) gene loci (HindIII). In the 38 consistent responders, the apoBSP24 allele was significantly more common than in the 17 individuals with a variable response (0.29 vs. 0.12; p < 0.05). No other polymorphism showed a significant frequency difference between groups. In the group as a whole, the correlation between the change in TC level in response to the first and second dietary change was 0.28 (p = 0.05), but those with one or more apoB SP24 alleles and those with the apoCIII genotype CC had a significantly higher correlation than those with other genotypes (0.46 (p = 0.05) vs. 0.12 (NS) and 0.31 (p = 0.05) vs. 0.02 (NS), respectively). In the group as a whole, mean response left TC 10% higher on the SFA than on the PUFA diet, and neither apoB nor apoCIII genotypes affected the magnitude of this response. However, individuals with the LPL HindIII genotype H+ H+ had a significantly smaller change in mean TC in response to diet than those with one or more H- allele (9.3% vs. 14.4%; p = 0.03). Thus variation at the apoB and apoCIII loci affects the consistency of response to change in dietary fat content, while variation at the LPL gene locus affects magnitude of response.

Strain among caregivers: comparing the experiences of African American and Hispanic caregivers of Alzheimer's relatives

This study of the experiences of seventy-six Black and eighty-six Hispanic caregivers of Alzheimer's relatives sought to determine the factors characterizing the caregiving process and its outcomes, particularly personal and role strain, in each group. The findings reveal that Hispanics are more vulnerable to each type of strain and this may be partially attributed to their caring for more impaired relatives, their younger ages, and comparative lack of expressive supportive relationships. The mediating role played by culture and informal supports in the caregiving process is highlighted by the results as well as the need for the development of sensitive and appropriate interventions and supports.

Relationships of age and axis I diagnoses in victims of completed suicide: a psychological autopsy study

OBJECTIVE

Psychiatric illness is a potent risk factor for suicide, rates of which differ markedly with age. The purpose of this study was to examine whether the psychiatric diagnoses of suicide victims vary predictably with age.

METHOD

DSM-III-R axis I diagnoses of 141 persons aged 21 to 92 years who had completed suicide were established by the psychological autopsy method. Multiple logistic regression analyses were used to determine whether age, gender, or their interaction predicted the presence of specific disorders.

RESULTS

One or more axis I conditions were diagnosable in 90.1% of the suicide victims. Substance use disorders were most frequent, followed by mood disorders and primary psychotic illness. Younger age at death was a significant predictor of substance abuse or dependence and primary psychoses, while older age predicted major mood disorders. Comorbidity of substance use and mood disorders was common. Among victims with substance abuse or dependence, older age at death predicted major depression; among victims with mood disorders, younger age at death predicted comorbid substance abuse or dependence.

CONCLUSIONS

The distribution of psychiatric illnesses in suicide victims differs across the life course. Age-related patterns of addictive and psychotic disorders echo their prevalence in the general population. In contrast, the relationship between age and mood disorders among suicide victims is distinctly different from that of the general population. These findings suggest that risk for suicide increases with age in individuals with major affective illness. Depressed elderly men are particular targets for suicide prevention strategies.

Human performance during exposure to toluene

PURPOSE

The purpose of this research was to examine the effects of inhalation of toluene on respiratory function and neuropsychological performance of humans.

METHODS

We exposed six healthy adults to 100 ppm toluene or air (control) for 6 h, in a double-blind, randomized fashion, with exposures separated by at least 14 d and including 30 min of exercise at a level that quadrupled minute ventilation. Blood and exhaled air toluene levels were measured before, during, immediately, and 1 and 2 h post-exposure. Lung function was measured before and immediately after exposure. Three repetitions of two computerized neuropsychological tests were performed, including a brief standard neuropsychological battery (ANAM) and a 1-h complex performance test (SYNWORK). Statistical analysis of the psychological data was conducted as a repeated measures ANOVA.

FINDINGS

Following exercise, the mean blood and exhaled air toluene levels averaged 1.5 micrograms and 28 ppm, respectively. Lung function was unchanged post-exposure. On the SYNWORK test, the Composite score obtained over time during toluene exposure was lower than that during room air (F = 29.20, p = 0.005), with the score from the final hour reduced by 10%. On standard neuropsychological tests, latency but not accuracy proved the sensitive measure for five of the seven subtests presented.

CONCLUSIONS

Performance of complex tests and response time to simple brief tests can be disrupted by toluene inhalation at 100 ppm. Differences in performance between air and toluene conditions were greatest after exercise, indicating that physical activity may enhance the response to volatile organic solvents.

Cross-discipline disparities in perceptions of mental disorders in a long-term care facility

OBJECTIVES

This study compared prevalence rates of mental disorders in a single long-term care facility as perceived by three professional disciplines and compared professionals' perceptions with two standardized measures of psychopathology.

DESIGN

Comparison of (1) prospective standardized psychiatric evaluations performed by psychiatrists, (2) chart reviews of mental disorders as documented by primary care physicians, and (3) interviews of nurses.

SETTING

The residential health care facility at Monroe Community Hospital in Rochester, New York.

PARTICIPANTS

A 20% random sample of adult residents, stratified by ward (n = 80).

MEASUREMENTS

Prevalence rates of psychopathology as determined by each data collection method: psychiatric diagnoses as determined by psychiatrists and primary care physicians, the Brief Psychiatric Rating Scale, and the Psychogeriatric Dependency Rating Scale.

RESULTS

Prevalence rates of psychopathology ranged from 60 to 91% across discipline-specific data collection methods. Using psychiatrists' diagnoses as the benchmark, primary care physicians and nurses underestimated the prevalence of mental disorders, particularly organic mental disorders. All disciplines agreed on the presence of personality and developmental disorders. The Brief Psychiatric Rating Scale and Psychogeriatric Dependency Rating Scale validated perceptions of psychopathology by psychiatrists and nurses, but not by primary care physicians' chart diagnoses.

CONCLUSION

Disparities in perceptions of mental disorders across disciplines pose a threat to patient care and suggest a need for more reliable incorporation of mental health expertise in the long-term care setting.

Medical-legal pitfalls for the breast surgeon: incomplete mammographic localization of suspicious lesions and the correlation between palpable and mammographic abnormalities

In approximately 5 per cent of mammographically detected lesions, the mammographic abnormality is present in only one view, either craniocaudal or mediolateral. In such a scenario, the physician has been left with the option of closely following the lesion, hoping it will eventually become apparent in two views, or guessing the approximate location of the lesion for subsequent open biopsy. However, with today's advances in technology, CT scan and its production of a three-dimensional image can compensate for mammography's two-dimensional limitation. With diminished need for identification on two mammographic views, localization in these instances falls more within the realm of possibility. This paper highlights Moffitt Cancer Center's experience with CT-directed breast biopsy as an alternative to close follow-up or blind-biopsy. In addition, because palpable breast abnormalities may not be the same as mammographic abnormalities, the report details the accuracy of CT-directed biopsy in allowing the surgeon to perform precise open biopsy, thus avoiding medical-legal exposure.

Persistent Epstein-Barr virus infection in the common marmoset (Callithrix jacchus)

Epstein-Barr virus (EBV) infection of the common marmoset causes long-term infection, with production of antibodies to virus-induced antigens, without clinical illness. Attempts to show the presence of EBV DNA in saliva of infected animals by PCR were initially unsuccessful, although slot-blot hybridization analysis demonstrated that viral DNA was present. Further investigations showed that most samples of pilocarpine-induced saliva, and 33% of the samples of whole mouth fluids (WMF) tested, were inhibitory to PCR. Similar results were found using human WMF. A method of assessing samples of marmoset WMF for the presence of EBV, by PCR using an EBV BamHI W probe, and removing inhibition with Chelex 100, is described. A total of 202 samples from 21 EBV infected, and seven non-infected animals was tested. Five seropositive animals shed virus on every occasion, and 15 intermittently. Two marmosets, infected as neonates, showed progressively increasing humoral responses to viral antigens, and shed virus on every occasion tested over 3 years. When mated with uninfected animals, the latter seroconverted 4 and 6 weeks later, respectively, and later shed virus into their WMF. The naturally infected animals were paired with naive marmosets, and were able to pass on infection. These results establish that long-term, permissive EBV infection occurs in the common marmoset, and demonstrate again the similarities in the response to EBV between marmoset and man.

Age-related decline in central cholinergic function demonstrated with scopolamine

Scopolamine hydrobromide was administered intravenously to 23 normal subjects (40-89 years) in doses of 0.1 mg, 0.25 mg, and 0.5 mg, in a double-blind. Placebo-controlled, random-order fashion. The effects of scopolamine, as compared to placebo, were assessed using a comprehensive cognitive test battery, as well as behavioral and physiological measures. Scopolamine produced the expected dose-dependent impairments in most of the cognitive functions assessed. Behavioral and physiological measures were also affected, but only minimally. More importantly, there was a significant overall correlation between age and scopolamine-impaired performances on psychomotor speed, short-term recall, visual tracking speed, visuo-motor coordination, and sequencing ability. There was, however, some inter-individual variability in this phenomenon. The results provide further evidence that cholinergically mediated cognitive functions show an increased sensitivity to scopolamine with age, albeit with heterogeneity that bears further investigation.

Liquid assisted ventilation: an alternative ventilatory strategy for acute meconium aspiration injury

Evidence of surfactant inactivation by meconium has led to the use of exogenous surfactant therapy in the management of meconium aspiration syndrome (MAS). Liquid assisted ventilation has been shown to improve the cardiopulmonary function in lungs with high surface tension. We compared exogenous surfactant therapy with liquid assisted ventilation in the management of experimental acute meconium aspiration injury. Thirty-two newborn lambs were ventilated at peak inspiratory pressures of 13-16 cm H2O, positive end expiratory pressure of 3-4 cm H2O, fractional inspired oxygen concentration (FiO2) of 1.0, and a respiratory frequency range between 30 and 35 breaths/min. Baseline arterial blood gases, pulmonary function, and arterial blood pressure measurements were taken. All lambs were given 2-3 ml/kg of an unfiltered 25% meconium solution. Lambs were then randomized into either gas-ventilated meconium control, or one of three treatment groups: 1) surfactant; 2) partial liquid ventilation (PLV); or 3) total liquid ventilation (TLV) for 4 hours after meconium injury. All treated groups demonstrated a significant increase in arterial oxygenation (P < 0.05); surfactant and PLV-treated lambs demonstrated significantly decreased arterial PCO2 (P < 0.05). Compliance in all groups increased compared with injury values; compliance of the TLV group increased more than in all other treatment groups (P < 0.05). In addition, lung histology of the TLV group demonstrated clear, intact alveolar epithelium and homogeneously expanded alveoli, while no such improvement was evident in the other groups. These data suggest roles for both exogenous surfactant therapy and liquid assisted ventilation techniques in the management of MAS.

Comparison of two warfarin regimens in the prevention of venous thrombosis following total knee replacement

A prospective, randomized trial was conducted to compare the effectiveness and safety of warfarin given in two regimens in prevention of venous thrombosis after total knee replacement. Adult patients scheduled for primary or revision total knee replacement were randomly assigned to receive either a "two-step" warfarin regimen beginning 10-14 days pre-operatively or, alternatively, to begin warfarin the night before surgery. Post-operatively, the dose was adjusted in both groups to achieve a target International Normalized Ratio (INR) of 2.2 and prophylaxis was continued until venography on post-operative days five through nine. Bleeding was assessed by surgical blood loss, transfusion requirements, changes in hematocrit, and clinically identified bleeding complications. The occurrence of deep vein thrombosis was nearly the same in the two treatment groups, 39% in patients randomized to the two-step regimen as compared to 38% in those beginning the night before surgery. The occurrence of proximal vein thrombosis was also similar, 5% versus 7% (p = NS). Patients in the two-step group received 1.33 +/- 1.26 transfusions compared to 0.95 +/- 1.22 in the night before group (p < 0.05) and also had a lower nadir post-operative hematocrit of 26.7 +/- 3.1 as compared to 28.5 +/- 3.2 (p < 0.0001). Major bleeding complications were associated with excessively prolonged INRs and occurred in five patients in the two-step group and two in the night before group. Patients in both groups who developed thrombosis had a significantly lower INR on post-operative days two and three compared to those without thrombosis. We conclude that a prophylactic warfarin regimen for prevention of deep vein thrombosis after total knee replacement beginning the night before surgery is more convenient and may be associated with less bleeding than a regimen beginning warfarin 10-14 days pre-operatively. Careful control of anticoagulant intensity is needed to achieve maximum effectiveness and avoidance of bleeding complications.

Synthesis of 2-thiothiazolidine-4-carboxylic acid and its chromatography in rat and human urine

2-Thiothiazolidine-4-carboxylic acid (TTCA), the urinary biological monitoring marker for carbon disulfide in humans was synthesized by reacting carbon disulfide with L-cystine. Validation of TTCA purity required elemental as well as mass spectral and chromatographic analyses. Two reversed-phase high-performance liquid chromatographic columns in series were necessary to resolve picomole amounts of TTCA from rat and human urine background peaks on detection at 272 nm even after prior diethyl ether extraction from acidified urines in the presence of saturated sodium chloride. The isolation procedure for TTCA from urine had a recovery of 94.0 +/- 8.1% in the linear 1.1-330 microM concentration range (0.0165-4.95 nmol injected mass) with a coefficient of variation of 8.6%. The detection limit was about 100 nM (1.5 pmol injected mass).

Water escape performance of adult RCS dystrophic and congenic rats: a functional and histomorphometric study

The dystrophic Royal College of Surgeons (RCS) rat undergoes photoreceptor degeneration due to a hereditary defect in the retinal pigment epithelium. The congenic rat remains unaffected. Although the retinal degeneration is well characterized, few functional studies of this strain are available. We wished to compare the visual function of congenic and dystrophic RCS rats using a water escape paradigm that tested their ability to find a submersed, randomly placed platform using a light source as a clue. Three different behavioral experiments were sequentially performed on all animals: Experiment 1--The Light and Platform test measured the time to swim from the center of the pool to a platform located under a light clue. Each animal was given 10 trials. Experiment 2--The No Light with Platform test was performed as above except no light clue was used. Experiment 3--The Light and No Platform test was performed with a light clue but without a platform. The animal was allowed to swim for 2 min. All trials were videotaped. After the final experiment, the animals were sacrificed and a histomorphometric analysis of their retinas were performed. Expt. 1--The time to find the platform using light as a clue was greater for the dystrophic than for the congenic rats. Expt. 2--In the absence of light clue, there was no significant difference in performance between the congenic and dystrophic animals. Expt. 3--In the absence of a platform, a significantly greater amount of time was spent in the area indicated by the light clue by the congenic animals as compared to the dystrophic. Morphometric analysis revealed a mean number of 133 photoreceptor nuclear profiles/90 microns of retina for congenic rats as compared to 0.14 for dystrophic rats. This simplified version of the Morris water maze permits quantitative evaluation of visually-guided behavior in an important model of retinal degeneration.

Developmental neurotoxicity of methanol exposure by inhalation in rats

The possibility of widespread methanol exposure via inhalation stemming from its adoption as an automotive fuel or fuel component arouses concerns about the potential vulnerability of the fetal brain. This project was designed to help address such concerns by studying the behavior of neonate and adult rats following perinatal exposure to methanol vapor. Four cohorts of pregnant Long-Evans hooded rats, each cohort consisting of an exposure and a control group, were exposed to 0 parts per million (ppm) (control) or 4,500 ppm methanol vapor for six hours daily beginning on gestation day (GD) 6 with dams and pups then being exposed postnatal day (PND) 21. Exposures took place in 2-m3 Rochester-type inhalation chambers while the animals remained in their plastic breeder cages. Prenatal and postnatal blood methanol concentrations were determined by gas chromatography. Blood methanol concentrations of the dams, measured immediately following a six-hour exposure, were approximately 500 to 800 micrograms/mL throughout gestation and lactation. Average blood methanol concentrations of the pups were about twice those of the dams. Because such results appeared consistently across the other cohorts, we decided to obtain additional data with Cohort 4. Once it had undergone the standard exposure protocol, we selected sets of extra pups from those that had not been assigned previously to the adult phase of behavioral testing. Each set was exposed once, at ages that extended out to PND 52, for one additional six-hour session of exposure to 4,500 ppm methanol. The blood methanol concentrations of these pups declined until about PND 48, at which time they approximated those of the dams. These findings might be accounted for by a process of metabolic maturation in the pups that remains to be identified.

Metallothionein induction and pulmonary responses to inhaled cadmium chloride in rats and mice

Inhaled CdCl2 is a pulmonary carcinogen in rats but not in mice. We hypothesized that pulmonary metallothionein (MT) induction may be different in both species and thereby may lead to different levels of protection from Cd-induced lung injury. Fisher-344 rats and B6C3F1 mice were exposed for 4 weeks to CdCl2 aerosols of 0, 30, 50, and 150 micrograms/m3 air or 0, 10, 30, and 100 micrograms/m3 air, respectively. Animals from each exposure group were terminated at 1, 30 and 133 days after the end of exposure. The lungs were lavaged for cell and biochemical analyses. Cadmium and MT in lavagate and lung tissue were measured. The retention half-time of pulmonary Cd was greater in mice (290 vs 90 days, p < 0.05). Cd exposure provoked an inflammatory response which was dose-dependent in both species, and while it was only short-lived in rats, it persisted throughout the observation period in mice at the high exposure concentrations. Mice were found to have a greater baseline level of MT (18.04 +/- 6.96 vs 11.7 +/- 1.98 micrograms MT/g control lung, p < 0.05). Mice showed greater inducibility of MT for a given CdCl2 exposure concentration; however, both species had a similar relationship between retained pulmonary Cd and MT induction though mice maintained increased MT levels for a longer period of time. The greater pulmonary baseline MT together with the longer presence of Cd-induced pulmonary MT may result in greater protection from Cd carcinogenicity in spite of the greater pulmonary Cd-induced inflammation in mice.

Association of pre mortem diagnosis and autopsy findings in pediatric intensive care unit versus emergency department versus ward patients

OBJECTIVE

As part of the overall quality assurance program for the Department of Pediatrics, we determined whether there were differences in the rates of unexpected autopsy findings between pediatric intensive care unit (ICU), emergency department, and ward patients.

DESIGN

Prospective, descriptive study.

SETTING

Tertiary care children's hospital.

PATIENTS

Pediatric deaths (n = 212).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Autopsies were obtained more frequently in emergency department patients (27/29 [93%]) compared with pediatric ICU (88/121 [73%] and ward (42/62 [68%]) patients (p = .03). The medical examiner's cases were more frequently from emergency department patients (22/27 [81%]) compared with pediatric ICU (39/88 [44%]) or ward (11/42 [26%]) patients (p < .001). We found unexpected autopsy findings in 19 (12%) of 157 patients. There were no unexpected findings from the medical examiner's cases. The most common unexpected findings were unidentified infections (n = 7 [three fungal, three viral, and one nonspecific]) and unrecognized cardiac malformations (n = 4). Unexpected findings occurred more frequently in pediatric ICU patients (16/88 [18%]) vs. emergency department (2/27 [7%]) or ward (1/42 [2%]) patients (p = .03). The occurrence rates of major unexpected findings (Class I and II) in pediatric ICU (7/79 [9%]), emergency department (2/27 [7%]), and ward (1/42 [2%]) patients were similar (p = .4). There were two Goldman's Class I unexpected findings in the pediatric ICU and emergency department patients, and one Goldman's Class I unexpected finding in the ward patients.

CONCLUSIONS

Autopsies were performed more frequently in emergency department patients. Class I through IV unexpected findings occurred more frequently in pediatric ICU patients compared with emergency department or ward patients. Autopsy examinations are an especially valuable diagnostic tool for pediatric ICU patients and physicians.

Brazilian Baccharis toxins: livestock poisoning and the isolation of macrocyclic trichothecene glucosides

Samples of the toxic Brazilian plant, Baccharis coridifolia, which is responsible for numerous cases of livestock poisoning in southern Brazil and Argentina, were collected during the growing season, and the toxicities in calves of the plant materials were correlated with the levels of macrocyclic trichothecenes present. Female plants in flower were considerably more toxic than male plants or plants not in flower. Plants not in flower were of intermediate toxicity. The female plants in flower typically contained 5-10 times the levels of toxins as were found in the male plants. In addition, six new glucosides of the macrocyclic trichothecenes were isolated and characterized. The most prominent glucosides, those of roridins A and E, were found in high levels in the female plants.

Cognitive performance and regional brain volume in human immunodeficiency virus type 1 infection

BACKGROUND

Brain atrophy has been reported to occur in advancing human immunodeficiency virus (HIV) infection, particularly in patients with HIV-related dementia. Atrophy of the caudate region, as assessed by magnetic resonance imaging measures, has been reported to correlate with cognitive impairment in patients with HIV infection; however, differences in the severity of HIV-induced immunosuppression may have contributed to these findings.

OBJECTIVE

To determine the relationship between regional brain volumes and cognitive performance in individuals with HIV infection.

PATIENTS AND METHODS

We evaluated 11 patients with advanced HIV disease by using neuropsychologic tests and quantitative magnetic resonance imaging volume analysis.

SETTING

University hospital, involving patients from a clinical trial.

RESULTS

Caudate volume, expressed as a ratio of total intracranial volume, correlated with performance on the Trails A and Grooved Pegboard tests, but not with other tests of memory, motor speed, or mood (adjusted for age and education). Hippocampal volume did not correlate with any of the neuropsychologic tests.

CONCLUSIONS

Caudate volume in patients with advanced HIV disease is associated with poor performance on neuropsychologic tests of complex motor and sequencing skills. Hippocampal volume does not appear to be related to impairment on neuropsychologic tests. These findings are independent of the degree of immunosuppression and the overall extent of brain atrophy; however, these results must be interpreted with some caution, given the limited sample size.

Autonomic control of heart rate after brain injury in children

OBJECTIVES

To study sequential changes in heart rate, respiratory rate, blood pressure, heart rate power spectra, and plasma catecholamine concentrations in patients with acute brain injury and correlate these variables with the severity of neurologic dysfunction and patient outcome.

DESIGN

Prospective, clinical study.

SETTING

Pediatric intensive care unit.

PATIENTS

Thirty-seven pediatric patients with acute brain injury caused by trauma, anoxia/ischemia, hemorrhage, or infection.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We found significant associations between low-frequency (0.01 to 0.15 Hz) heart rate power and severity of neurologic dysfunction (as assessed by the admission Glasgow Coma Scale) (p < .001) and patient outcome (as assessed by the Glasgow Outcome Scale) (p = .05). The admission (p = .05) and maximum (p < .001) values for low-frequency heart rate power and the minimum value for high-frequency (0.15 to 0.50 Hz) heart rate power obtained during hospitalization (p = .001) predicted an increased likelihood of survival. Ten brain-dead patients had significantly decreased low-frequency heart rate power (p = .008) and plasma norepinephrine (p = .015), epinephrine (p = .03), and dopamine (p = .04) concentrations when compared with six non-brain-dead patients with a Glasgow Coma Scale score of 3.

CONCLUSIONS

Our results imply that autonomic nervous system control of heart rate is disrupted in proportion to the degree of neurologic insult in children after acute brain injury. Thus, heart rate power spectral analysis and plasma catecholamine concentrations may prove to be useful adjuncts in determining severity of neurologic injury and prognosis for recovery in children suffering from brain injury. In addition, these techniques may aid in the determination of brain death.

Exposure to combined static and 60 Hz magnetic fields: failure to replicate a reported behavioral effect

Two experiments failed to confirm the Thomas, Schrot, and Liboff report that low-intensity magnetic fields disrupted the operant behavior of rats. In their experiment, food-deprived rats were trained to press a lever to obtain food pellets under a multiple fixed-ratio (FR) 30, differential reinforcement of low rate 18-24 s (DRL 18-24) schedule. After baseline training, the rats were exposed to a 30 min treatment in a different chamber prior to behavioral testing. When the treatment consisted of a horizontal 60 Hz magnetic field at 5 x 10(-5) Telsa aligned along the north-south axis combined with a static field that reduced the background to 2.61 x 10(-5) Telsa, the rate of lever pressing in the DRL component of the multiple schedule increased reliably during the immediately following test session. Changes in responding were not observed when the rats were exposed to either the static field or the 60 Hz field independently nor during sham exposures to the fields. In the present experiments, only the combined fields, i.e., those reported to be effective, were studied in rats using the same general behavioral and exposure protocol used by Thomas et al [1986a]. In experiment 1, the 2.61 x 10(-5) Telsa was achieved by reducing the vertical component of the static field. In experiment 2, both the horizontal and the vertical components were altered to match those used by Thomas et al. In both experiments additional magnetic field conditions were also studied to ensure that threshold values were exceeded and, in experiment 2, to address concerns about the role of harmonic frequencies of the 60 Hz field. The baseline performances approximated those of Thomas et al. Performances were compared between exposure, sham-exposure and control sessions. None of the exposure conditions altered any of the behavioral measures. The reasons for failing to replicate the results of Thomas et al. remain unknown.