Interpreting recruitment limitation in forests.

Studies of tree recruitment are many, but they provide few general insights into the role of recruitment limitation for population dynamics. That role depends on the vital rates (transitions) from seed production to sapling stages and on overall population growth. To determine the state of our understanding of recruitment limitation we examined how well we can estimate parameters corresponding to these vital rates. Our two-part analysis consists of (1) a survey of published literature to determine the spatial and temporal scale of sampling that is basis for parameter estimates, and (2) an analysis of extensive data sets to evaluate sampling intensity found in the literature. We find that published studies focus on fine spatial scales, emphasizing large numbers of small samples within a single stand, and tend not to sample multiple stands or variability across landscapes. Where multiple stands are sampled, sampling is often inconsistent. Sampling of seed rain, seed banks, and seedlings typically span <1 yr and rarely last 5 yr. Most studies of seeding establishment and growth consider effects of a single variable and a single life history stage. By examining how parameter estimates are affected by the spatial and temporal extent of sampling we find that few published studies are sufficiently extensive to capture the variability in recruitment stages. Early recruitment stages are especially variable and require samples across multiple years and multiple stands. Ironically, the longest duration data sets are used to estimate mortality rates, which are less variable (in time) than are early life history stages. Because variables that affect recruitment rates interact, studies of these interactions are needed to assess their full impacts. We conclude that greater attention to spatially extensive and longer duration sampling for early life history stages is needed to assess the role of recruitment limitation in forests.

Continuous intravenous terbutaline for pediatric status asthmaticus.

OBJECTIVES: To determine the clinical effects of intravenous terbutaline at >0.4 microg/kg/min in children with status asthmaticus; to describe the clinical findings associated with such therapy, including creatinine phosphokinase-myocardial band isoenzyme (CPK-MB) concentrations, electrocardiographic alterations, and decreased diastolic blood pressure (DBP) with terbutaline usage; and to assess the requirement for epinephrine to counteract the decrease in diastolic blood pressure. DESIGN: A retrospective review of children admitted with status asthmaticus who failed emergency room therapy and required intravenous terbutaline. SETTING: San Diego Children's Hospital Pediatric Intensive Care Unit. PATIENTS: Eighteen children with status asthmaticus, based on clinical and laboratory criteria, between September 1994 and July 1996. INTERVENTIONS: Epinephrine was added for below-normal decreases in diastolic blood pressure. MEASUREMENTS AND MAIN RESULTS: Continuous monitoring for arrhythmias, ST-segment changes, and DBP values during variations in the dose of intravenous terbutaline, with or without epinephrine. CPK-MB concentrations were determined in 15 of 18 patients. CONCLUSIONS: Intravenous terbutaline was well tolerated in asthmatic children for < or =305 continuous hours and at varying doses up to a maximum of 10 microg/kg/min. There was no relationship between the magnitude of CPK-MB concentrations and the terbutaline or epinephrine doses used. Arrhythmias were rare and not related to either terbutaline or epinephrine doses. However, ST-segment depression did occur in two patients requiring high-dose epinephrine. Terbutaline significantly lowered DBP when used between 0.4 and 1.0 microg/kg/min, which required epinephrine to be initiated. Epinephrine was not required at terbutaline doses of >2 microg/kg/min. There was no mortality.

Neurocognitive abnormalities in children after classic manifestations of Lyme disease.

BACKGROUND: In adults a subtle encephalopathy characterized primarily by memory impairment, irritability and somnolence may occur months to years after classic manifestations of Lyme disease. However, only limited information is available about whether there is an equivalent disorder in children. METHODS: Case series of five children seen in a Lyme disease clinic in a university referral center for evaluation of neurocognitive symptoms that developed near the onset of infection or months after classic manifestations of Lyme disease. The diagnosis was based on clinical symptoms, serologic reactivity to Borrelia burgdorferi and intrathecal antibody production to the spirochete. Evaluation included detailed neuropsychologic testing. After evaluation the children were treated with intravenous ceftriaxone for 2 or 4 weeks. Follow-up was done in the clinic and a final assessment was made by telephone 2 to 7 years after treatment. RESULTS: Along with or months after erythema migrans, cranial neuropathy or Lyme arthritis, the five children developed behavioral changes, forgetfulness, declining school performance, headache or fatigue and in two cases a partial complex seizure disorder. All five patients had IgG antibody responses to B. burgdorferi in serum as well as intrathecal IgG antibody production to the spirochete. Two patients had CSF pleocytoses and three did not. Despite normal intellectual functioning the five children had mild to moderate deficits in auditory or visual sequential processing. After ceftriaxone therapy, the four children in whom follow-up information was available experienced gradual improvement in symptoms. CONCLUSIONS: Children may develop neurocognitive symptoms along with or after classic manifestations of Lyme disease. This may represent an infectious or postinfectious encephalopathy related to B. burgdorferi infection.

Neuropsychological assessment of children and adolescents with systemic lupus erythematosus.

Neuropsychological assessments of adults with SLE have shown cognitive impairment, sequential processing deficits, memory loss, increased incidence of left handedness, learning disabilities and emotional distress compared with healthy individuals or subjects with other medical conditions. Neuropsychological testing regarding these variables in children and adolescents with SLE has been infrequently reported. For this study, eight children with SLE (age 9-17 years at diagnosis) were assessed with neuropsychological testing at a median of 10.5 months (range 1 week to 30 months) after diagnosis. Tests included Wechsler Intelligence Scale for Children-Revised or Wechsler Adult Intelligence Scale-Revised, Wide Range Achievement Test-Revised, Standard Binet Intelligence Scale Fourth Edition Memory Subtests or Wechsler Memory Scale (all mean = 100 +/- 15) and Gates MacInitie Reading Comprehension Test, Achenbach Child Behavior Checklist and Achenbach Youth Self Report. Mean intellectual scores were in the low average range (Wechsler Full Scale mean = 85.0 +/- 11.9, Verbal Scale mean 85.2 +/- 13.9, Performance Scale mean = 88.0 +/- 13.9). Academic achievement was globally depressed (reading recognition mean = 79.5 +/- 22.0, spelling mean = 78.9 +/- 23.5), especially in arithmetic (mean = 70.5 +/- 14.9). Children with SLE averaged 5 years behind grade placement in reading comprehension. Visual memory was also depressed in patients with SLE. Behavior ratings failed to demonstrate any significant aberrations in the test subjects.

Mediating factors of stress on mothers of seriously ill, hospitalized children.

The present study examined 10 variables for their importance in mediating maternal adjustment to the stress of a child's hospitalization as measured by the State scale of the State-Trait Anxiety inventory and the Hopkins Symptom Checklist. The results showed significant mediating effects for the Trait scale of the State-Trait Anxiety Inventory, a self-report of coping, and socioeconomic status. Level of trait anxiety was the single best predictor of stress for both criterion measures.