Thalamic neuron apoptosis emerges rapidly after cortical damage in immature mice.

In adults and children, head trauma can have long-term neuropathological and functional consequences. The thalamus is a major site of remote neurodegeneration after cortical damage in adult humans and experimental animals, but less is known about thalamic responses to cortical injury in the immature brain. This study introduces an in vivo model of axotomy/target deprivation-induced neuronal apoptosis in the dorsal lateral geniculate nucleus of the thalamus produced by unilateral ablation of the occipital cortex in the immature mouse. We specifically examined whether occipital cortex ablation in the immature brain causes apoptotic death of projection neurons in the dorsal lateral geniculate nucleus. After unilateral occipital cortex aspiration, 10-day-old C57BL/6 mice were recovered for up to 28 days. Fluorogold-prelabeled thalamocortical projection neurons were apoptotic at 36-48 h after ablation. The structural progression of apoptosis in the immature lateral geniculate nucleus reveals typical chromatolytic morphology by 18-24 h, followed by cytoplasmic shrinkage and chromatin condensation characteristic of end-stage apoptosis after 36-48 h. Electron microscopy confirmed the presence of apoptosis. This study shows internucleosomal DNA fragmentation and expression of cleaved caspase-3 occurs rapidly, being noted first at 18 h, well before the peak of apoptotic cell death occurring at 36 h after cortical damage in the immature brain. From these data we suggest that axotomy/target deprivation-induced cell death in the immature brain may: (1) differ from that previously reported in adult mice with respect to the time required for progression to cell death; (2) be mediated by caspase-3 activation.

Injury-induced apoptosis of neurons in adult brain is mediated by p53-dependent and p53-independent pathways and requires Bax.

The mechanisms of injury-induced apoptosis of neurons within the CNS are not understood. We used a model of cortical injury in rat and mouse to induce retrograde neuronal apoptosis in thalamus. In this animal model, unilateral ablation of the occipital cortex causes unequivocal apoptosis of corticopetal projection neurons in the dorsal lateral geniculate nucleus (LGN) by 7 days postlesion. We tested the hypothesis that p53 and Bax regulate this retrograde neuronal apoptosis. We found, by using immunocytochemistry, that p53 accumulates in nuclei of neurons destined to undergo apoptosis. By immunoblotting, p53 levels increase ( approximately 150% of control) in nuclear-enriched fractions of the ipsilateral LGN by 5 days after occipital cortex ablation. p53 is functionally activated in nuclear fractions of the ipsilateral LGN at 5 days postlesion, as shown by DNA binding assay (approximately fourfold increase) and by immunodetection of phosphorylated p53. The levels of procaspase-3 increase at 4 days postlesion, and caspase-3 is activated prominently at 5 days postlesion. To identify whether neuronal apoptosis in the adult brain is dependent on p53 and Bax, cortical ablations were done on p53 and bax null mice. Neuronal apoptosis in the dorsal LGN is significantly attenuated (approximately 34%) in p53(-/-) mice. In lesioned p53(+/+) mice, Bax immunostaining is enhanced in the ipsilateral dorsal LGN and Bax immunoreactivity accumulates at perinuclear locations in dorsal LGN neurons. The enhancement and redistribution of Bax immunostaining is attenuated in lesioned p53(-/-) mice. Neuronal apoptosis in the dorsal LGN is blocked completely in bax(-/-) mice. We conclude that neuronal apoptosis in the adult thalamus after cortical injury requires Bax and is modulated by p53.

Working with families of suddenly and critically ill children: physician experiences.

OBJECTIVE: To describe physicians' experiences in attempting to provide optimal care for families of children who suffer from sudden, acute life-threatening conditions (SALTC). DESIGN: To generate descriptive data in this exploratory study, we used qualitative methods including focus groups and in-depth interviews. Transcripts of focus groups and interviews were analyzed for content using standard phenomenologic analysis methods, which resulted in a participant-generated conceptual model of optimal care for families of children with SALTC. SETTING: The intensive care unit of an urban pediatric teaching hospital. PARTICIPANTS: Twenty-two pediatric intensive care unit physicians, including residents, fellows, and attendings. INTERVENTION: None. MAIN OUTCOME MEASURES: Each participating physician provided qualitative descriptions of experiences caring for families of children with SALTC. RESULTS: Physicians identified 4 components of optimal care for families: (1) providing timely, accurate information about their child; (2) maintaining privacy for confidential discussions and personal grieving; (3) giving adequate emotional support; and (4) granting family members the right to hold and comfort their dying child. Physicians also described barriers to, and facilitators of this optimal care. CONCLUSIONS: Descriptive information provided in this exploratory study offers a complex model of optimal family care. Issues that affect the quality of care to families include those related to the context of providing care in a large teaching hospital, as well as subtleties of communication between parents and staff. Physicians' beliefs about optimal care of families in the pediatric intensive care unit revealed implications for both practice and training in pediatrics.

Early hyperthermia after traumatic brain injury in children: risk factors, influence on length of stay, and effect on short-term neurologic status.

OBJECTIVES: a) To determine the risk factors for early hyperthermia after traumatic brain injury in children; b) to identify the contribution of early hyperthermia to neurologic status at pediatric intensive care unit (PICU) discharge and to PICU length of stay in head-injured children. STUDY DESIGN: Observational cohort study. SETTING: PICU at a tertiary care, university medical center. PATIENTS: Children (n = 117) admitted to a PICU from July 1995 to May 1997 with traumatic brain injury. These children had a median age of 5.4 yrs (3 wks to 15.2 yrs old), and 33.4% were girls. MEASUREMENTS AND MAIN RESULTS: Early hyperthermia (temperature >38.5 degrees C within the first 24 hrs of admission) occurred in 29.9% of patients admitted to the PICU with traumatic brain injury. Risk factors predicting early hyperthermia included Glasgow Coma Scale score in the emergency department < or =8, pediatric trauma score < or =8, cerebral edema or diffuse axonal injury on initial head computed tomography scan, admission blood glucose >150 mg/dL (8.2 mmol/L), admission white cell count >14,300 cells/mm3 (14.3 x 10(9) cells/L), and systolic hypotension. The presence of early hyperthermia significantly increased the risk for Glasgow Coma Scale score <13 at PICU discharge (odds ratio [OR] 9.7, 95% confidence interval [CI] 2.8, 24.4) and PICU stay > or =3 days (OR 13.8, CI 5.1, 37.5). When we used multiple logistic regression models including injury severity and hypotension, early hyperthermia remained an independent predictor of lower Glasgow Coma Scale score at PICU discharge (OR 4.7, CI 1.4, 15.6) and longer PICU length of stay (OR 8.5, CI 2.8, 25.6). CONCLUSIONS: Early hyperthermia is independently associated with a measure of early neurologic status and resource utilization in children with traumatic brain injury serious enough to require PICU admission. These results support the prevention of hyperthermia in the management of traumatic brain injury in children. Further research is required to understand the mechanisms of this response and to identify appropriate preventive or therapeutic interventions.

Chronic abdominal wall pain. Diagnostic validity and costs.

Chronic abdominal wall pain (CAWP) is common and frequently mistaken for visceral pain. We determined the stability of this diagnosis with Main Outcome Measures of: (a) change of pain intensity after local anesthetic-corticosteroid injection, (b) pain relief after three or more months follow-up, and (c) costs of diagnostic procedures for visceral causes of abdominal pain in patients with confirmed CAWP. Seventy-nine patients fulfilled tentative criteria for CAWP; 72 (91%) experienced > or = 50% pain relief with anesthetic injection and were followed for at least three months (mean = 13.8 months). Abdominal pain in four patients was later diagnosed as caused by visceral disease. CAWP was confirmed in 56 of remaining 68 patients; 12 of 19 patients with recurrent pain were unavailable for re-injection of anesthetic. Thirty patients with confirmed CAWP had had diagnostic procedures to exclude visceral disease costing almost $700 per patient. CAWP is usually easily identified and treated; greater awareness should minimize misdiagnosis.

Comparison of intrapulmonary percussive ventilation and chest physiotherapy. A pilot study in patients with cystic fibrosis.

STUDY OBJECTIVE: To compare the intrapulmonary percussive ventilator (IPV) to chest physiotherapy (P&PD) with respect to acute changes in (1) pulmonary function and (2) sputum physical properties in patients with cystic fibrosis (CF). DESIGN: Randomized crossover. SETTING: Community-based CF referral center. PARTICIPANTS: Nine nonhospitalized person (range, 7 to 40 years; median, 12.4 years) with moderate to excellent Shwachman scores. INTERVENTIONS: Three treatment regimens: (1) 2.5 mg albuterol delivered via IPV (internal percussive component activated); (2) 2.5 mg. albuterol delivered via IPV (internal percussive component inactivated), followed by P&PD; and (3) 2.5 mg albuterol delivered via updraft nebulizer, followed by P&PD. MEASUREMENTS AND RESULTS: Outcome measures included pulmonary function testing (PFTs) and quantitative and qualitative sputum analysis. Among the three treatment groups, there were no significant differences in the change in predicted PFTs 1 h or 4 h after treatment, nor in the volume of sputum expectorated in the first 4 or in the subsequent 20 h. Among patients receiving IPV, more serious disease was associated with greater improvement in FEF25-75 1 h after treatment, but these differences disappeared by 4 h. There were no meaningful differences in viscoelastic characteristics of sputum expectorated after each treatments. Participants reported general satisfaction with no adverse effects while using IPV. CONCLUSIONS: This initial pilot study suggests (1) stable patients with CF tolerated one treatment of IPV without adverse sequelae, and (2) IPV was as effective as standard aerosol and P&PD in improving short-term PFT results and enhancing sputum expectoration.

Prevalence of childhood disability in a southern Indian city: independent effect of small differences in social status.

A random sample of mothers living in two neighbourhoods of a southern Indian city were interviewed in order to determine the prevalence of serious disability in children 2-9 years old. These areas were selected because residents constitute either the lowest class or the next higher socioeconomic class (next-to-lowest class), with monthly incomes of US$ 10-15 and 32-42 respectively. A previously validated screening instrument was used with documented sensitivity of 100% and specificity of 95% when applied under similar conditions. Disability was found to be more common among children of the lowest class families (17.2%) when compared with the next-to-lowest class families (8.4%); with an odds ratio (OR) of 2.36 (95% confidence interval (CI): 1.08-3.64). Specific types of disability were examined and found to be consistently more prevalent in the lowest class. These results suggest that comparatively small differences in social status can be associated with important differences in health status.

PIP: Researchers analyzed data on 640 2-9 year old children who lived in either a lowest social status neighborhood or a next to lowest social status neighborhood in Madurai in Tamil Nadu State in India to determine whether small differences at the lowest end of the socioeconomic scale would be associated with differential health status. Interviewers spoke with the families in December 1990 and used a screening tool with 100% sensitivity and 95% specificity previously validated in a community based study in Bangladesh. 17.2% of families in the slum had a child with a disability compared to 8.4% in the next to lowest social class area (odds ratio=2.36 [OR]; p.001). Further disability prevalence was consistently higher among children from the lowest social class, especially sensory (4.8% vs. 0.9%; p=.003), neuromotor (8.1% vs. 3%; p=.005), and cognitive disabilities (3.5% vs. 1.2%; p=.05). In fact, the multiple logistic regression which took in consideration age, gender, number of children in the household, birth order, and social status revealed that the only significant and meaningful relationship affecting childhood disability was lowest social status (OR=2.39). These results demonstrated that the lowest status families were 2.39 times more likely to have disabled children even though the differences in income between the 2 deprived groups was small. The study did not identify what mechanism was responsible for the disparity between the 2 groups, however. The researchers encouraged other studies to identify the mechanism for disability among the lowest social class and yet not among another very resource poor group.

Elevated brain lactate accumulation and increased neurologic deficit are associated with modest hyperglycemia in global brain ischemia.

This study determined if hyperglycemia: (1) augments ischemic cerebral cortical lactate accumulation during complete cerebral ischemia; and (2) exacerbates subsequent neurologic morbidity and mortality. Dextrose (D5W, n = 8) or normal saline (n = 6) was administered i.v. prior to 10 min of global cerebral ischemia induced by normothermic cardiac arrest in dogs. Before arrest plasma glucose was significantly higher in the D5W-treated group than saline-infused (407 +/- 31 vs. 11 9 +/- 20 mg/dl, P less than 0.05). By 6 h post-arrest, seven of eight D5W-infused dogs died, compared to one of six saline-infused dogs (P = 0.002). D5W-infused dogs showed significantly greater neurologic deficit at 2, 6, and 12 h post-arrest. In a complementary protocol, dogs were pretreated in the same manner, however, six cerebral cortical brain biopsies were taken before, during, and immediately after cardiac arrest. Plasma glucose was 320 +/- 17 mg/dl in the D5W-infused dogs and lower (P less than 0.001), 140 +/- 5 mg/dl, in the saline-infused group. Cerebral cortical lactate accumulation was slightly but significantly greater during ischemia and early reperfusion in animals receiving dextrose. Neither plasma nor cerebrospinal fluid (CSF) creatine kinase isoenzymes nor plasma or CSF lactate concentrations, measured during and for 25 min after cardiac arrest, served as a good prognostic indicator of 24 h neurologic morbidity or mortality. Therefore, induction of complete cerebral ischemia in the presence of moderate hyperglycemia is associated with profound neurologic dysfunction and striking mortality. A qualitative but not quantitative increase in brain lactate accumulation is consistent with the hypothesis that lactate may contribute to the increased severity of neurologic dysfunction with hyperglycemia.

Hyperglycemia exacerbates and insulin fails to protect in acute renal ischemia in the rat.

Hyperglycemia worsens ischemic injury in several ischemic models. To determine whether renal lactate accumulation was associated with hyperglycemia-exacerbated postischemic renal dysfunction and mortality, halothane-anesthetized rats underwent right nephrectomy and 45 min of left renal artery and vein occlusion. Prior to ischemia, rats received saline (n = 22), glucose (2 g/kg, n = 22), or insulin (4 U/kg, n = 18). Sham-operated glucose-treated rats (2 g/kg, n = 4) underwent right nephrectomy and no vascular occlusion. As anticipated, glucose pretreatment elevated plasma glucose, while insulin pretreatment lowered plasma glucose; both were significantly different from values in saline controls. Creatinine was unchanged in sham-operated rats but was significantly higher in glucose-treated rats at 24 and 48 hr postischemia compared to saline controls. No statistical differences in creatinine were found when comparing saline controls to insulin-treated rats. Eighteen percent of glucose-treated rats survived to 72 hr postocclusion, while 45% of insulin-treated rats, 73% of saline control rats, and 100% of sham-operated rats survived this period. In a separate but identical treatment protocol, renal tissue was serially sampled and lactate content was determined in rats pretreated with saline (n = 7), glucose (n = 6) or insulin (n = 6) or sham-operated (n = 2) and receiving identical operation. Tissue lactate concentration did not change during serial sampling in the sham group. During ischemia, lactate was significantly higher in glucose-treated rats and significantly lower in insulin-treated rats as compared to saline controls. The adverse effects of exogenous glucose and attendant hyperglycemia on renal function during normothermic renal ischemia are demonstrated.(ABSTRACT TRUNCATED AT 250 WORDS)

Continued circulatory support: effect of epinephrine or dopamine on 24-hour survival and neurologic function in dogs.

The effects on 24-h survival and neurologic function were compared following continued postresuscitation circulatory support with epinephrine or dopamine. Cardiopulmonary arrest was induced by ventricular fibrillation. After 10 min, resuscitation efforts were initiated including i.v. infusion of either epinephrine (6 micrograms/kg per min, 11 dogs) or dopamine (10 micrograms/kg per min, 14 dogs) for continued circulatory support. There was no difference detected in duration of circulatory support, although dogs receiving epinephrine required more lidocaine (3.3 +/- 0.4 vs. 1.8 +/- 0.3 mg/kg, P = 0.005). Likewise, there was no statistically significant difference detected in MAP or HR between groups at any time tested. However, dogs receiving epinephrine had significantly worse neurologic function at 6 and 12 h postarrest. Mean survival time (20.3 +/- 1.2 vs. 15.3 +/- 1.9 h, P = 0.028) and overall survival (P = 0.027, survival curve analysis) were significantly longer for dogs receiving dopamine. Plasma glucose in the first 6 h postarrest was significantly higher in dogs receiving epinephrine (P = 0.006). These results suggest that the use of epinephrine for continued vasopressor support in cardiopulmonary resuscitation may contribute to decreased survival and poorer neurologic function in this controlled experimental setting. It is reasonable to propose that similar responses to these commonly used circulatory support agents occur clinically. Therefore, continued vasopressor support with dopamine rather than epinephrine may be justified in the setting of cardiac resuscitation.

Neutrophil depletion fails to improve neurologic outcome after cardiac arrest in dogs.

We tested the hypothesis that polymorphonuclear leukocytes (neutrophils) contribute to morbidity and mortality in a canine model of cardiac arrest-induced central nervous system ischemia. Circulating neutrophils were depleted by administration of a neutrophil-specific sheep immune serum before a ten-minute cardiac arrest in ten experimental animals. Ischemic damage measured by a neurologic deficit score in these animals was compared with that in 12 animals that received either vehicle control or nonimmune sheep serum. Animals receiving immune serum averaged 89% depletion of neutrophils immediately after resuscitation (neutrophils +/- SEM: 703 +/- 123/mm3 after antiserum versus 6,384 +/- 1,171/mm3 before immune serum) and 70% depletion over the first three hours after resuscitation. Neurologic deficit scores assessed at one, two, six, 12, and 24 hours after arrest did not vary between depleted dogs and controls. Overall survival time in neutrophil-depleted dogs was less than in controls (15.5 +/- 1.3 versus 19.5 +/- 1.3 hours; P = .04). These results suggest that neutrophils may not contribute to clinically important central nervous system dysfunction after resuscitation from a ten-minute cardiac arrest.

Somatosensory evoked potentials of the dog: recording techniques and normal values.

Median and tibial nerve somatosensory evoked potentials (SSEPs) of 5 sedated dogs were studied to determine their normal features and optimal stimulation and recording techniques. Cortical potentials were mapped from an extensive array of skull electrodes as each limb was independently stimulated with subdermal needles. The effects of bandpass and stimulus intensity and rate were also assessed. Three cortical components (P1, N1, P2) were evoked by median or tibial nerve stimulation and were localized along the coronal suture at lateral and medial electrodes, respectively. SSEP voltage varied much more than morphology, topography, or latency. The inion was a stable, indifferent reference site. Cortical SSEP frequency content was mostly below 250 Hz. Maximal SSEP voltage was achieved only at stimulus intensities 2-3 times motor threshold. Appropriate methods minimize technical difficulties and consistently yield legible SSEPs.

Effect of the aminosteroid U74006F after cardiopulmonary arrest in dogs.

The oxygen free radical-induced lipid peroxidative reactions that occur during resuscitation from normothermic cardiac arrest may contribute to the degree of neurologic dysfunction sustained. A blinded, randomized experimental trial was performed to determine whether U74006F, a potent inhibitor of lipid peroxidation, reduces morbidity and 24-hour mortality after 10 minutes of normothermic cardiopulmonary arrest; ventricular fibrillation was induced by electrical stimulation in 24 open-chest, halothane-anesthetized dogs, and circulation was reestablished by direct cardiac compressions, administration of a standardized drug regime, and internal countershocks. When spontaneous circulation was restored, a bolus injection of 1.5 mg/kg U74006F (n = 12) or 25 mM citrate vehicle (n = 12) was infused intravenously in 15 minutes and an infusion was continued at 0.125 mg/kg/hr for the next 12 hours. In the drug-treated group, plasma U74006F concentration averaged 0.13 microgram/ml between 3 and 12 hours after cardiac arrest. By 24 hours after arrest, 10 of 12 (83%) vehicle-treated dogs had died but only four of 12 (33%) U74006F-treated dogs had died (p = 0.017). U74006F-treated dogs survived significantly longer (mean +/- SEM 22 +/- 1 hr) than vehicle-treated dogs (18 +/- 1 hr), with significantly better neurologic function 1, 2, and 24 hours after arrest. Plasma fatty acid hydroperoxide concentrations 12 hours after arrest were 88 +/- 81 pmol/ml in U74006F-treated and 241 +/- 49 pmol/ml in vehicle-treated dogs (p less than 0.05). Vitamin E concentrations were significantly higher in the plasma of U74006F-treated dogs 2, 3, and 6 hours after arrest compared with vehicle-treated dogs.(ABSTRACT TRUNCATED AT 250 WORDS)

Growth hormone promoted tyrosyl phosphorylation of growth hormone receptors in murine 3T3-F442A fibroblasts and adipocytes.

Because many growth factor receptors are ligand-activated tyrosine protein kinases, the possibility that growth hormone (GH), a hormone implicated in human growth, promotes tyrosyl phosphorylation of its receptor was investigated. 125I-Labeled human GH was covalently cross-linked to receptors in intact 3T3-F442A fibroblasts, a cell line which differentiates into adipocytes in response to GH. The cross-linked cells were solubilized and passed over a column of phosphotyrosyl binding antibody immobilized on protein A-Sepharose. Immunoadsorbed proteins were eluted with a hapten (p-nitrophenyl phosphate) and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. The eluate from the antibody column contained an Mr 134,000 125I-GH-receptor complex. A similar result was obtained when the adipocyte form of 3T3-F442A cells was used in place of the fibroblast form. O-Phosphotyrosine prevented 125I-GH-receptor complexes from binding to the antibody column, whereas O-phosphoserine and O-phosphothreonine did not. In studies of GH-promoted phosphorylation in 3T3-F442A fibroblasts labeled metabolically with [32P]Pi, GH was shown to stimulate formation of a 32P-labeled protein which bound to immobilized phosphotyrosyl binding antibodies. The molecular weight of 114,000 obtained for this protein is similar to that expected for non-cross-linked GH receptor. The Mr 114,000 phosphorylated protein could be immunoprecipitated with anti-GH antibody, indicating that GH remained noncovalently bound to this protein during absorption to and elution from the immobilized phosphotyrosyl binding antibody. Phosphoamino acid analysis after both limited acid hydrolysis and extensive base hydrolysis of the Mr 114,000 phosphoprotein confirmed the presence of phosphotyrosyl residues.(ABSTRACT TRUNCATED AT 250 WORDS)