The Impact of Short and Long-Term Exercise on the Expression of Arc and AMPARs During Evolution of the 6-Hydroxy-Dopamine Animal Model of Parkinson's Disease

The loss of nigral dopaminergic neurons typical in Parkinson's disease (PD) is responsible for hyperexcitability of medium spiny neurons resulting in abnormal corticostriatal glutamatergic synaptic drive. Considering the neuroprotective effect of exercise, the changes promoted by exercise on AMPA-type glutamate receptors (AMPARs), and the role of activity-regulated cytoskeleton-associated protein (Arc) in the AMPARs trafficking, we studied the impact of short and long-term treadmill exercise during evolution of the unilateral 6-hydroxy-dopamine (6-OHDA) animal model of PD. Wistar rats were divided into sedentary and exercised groups, with and without lesion by 6-OHDA and followed up to 4 months. The exercised groups were subjected to a moderate treadmill exercise 3×/week. We measured the proteins tyrosine hydroxylase (TH), Arc, GluA1, and GluA2/3 in the striatum, substantia nigra, and motor cortex. Our results showed a higher reduction of TH expression in all sedentary groups when compared to all exercised groups in striatum and substantia nigra. In general, larger changes occurred in the striatum in the first and third months after training. After 1 month of exercise, there was significant increase of GluA2/3 with concomitant reduction of GluA1 and Arc. As a balanced system, these changes were reversed in the third month, showing an increase of Arc and GluA1 and decrease of GluA2/3. Similar results for GluAs and Arc were observed in the motor cortex of the exercised animals. These modifications may be relevant for corticostriatal circuits in PD, since the exercise-dependent plasticity can modulate GluAs expression and maybe neuronal excitability.

Atypical presentation of Leber's hereditary optic neuropathy associated to mtDNA 11778G>A point mutation--A case report

Leber's hereditary optic neuropathy (LHON) is a maternally inherited mitochondrial disorder characterized by bilateral loss of central vision, most frequently found in young adult males. In most patients there are no other neurological manifestations and cerebral neuroimaging is normal, but some rare cases of "LHON plus" have been described. Classical LHON is mainly associated to mitochondrial DNA (mtDNA) mutations 11778G>A, 3460G>A and 14484T>C, localized in the coding regions for ND4, ND1 and ND6 of the complex I subunits of mitochondrial respiratory chain (MRC), respectively. We report a 12-year-old girl who presented with reduced visual acuity secondary to optic atrophy at 8 months of age, which led to a clinical diagnosis of LHON. Psychomotor regression, refractory epilepsy and progressive neurological abnormalities developed subsequently. Skeletal muscle histology and biochemical MRC function were normal (evaluated by dual wavelength spectrophotometry). A 11778G>A mtDNA point mutation (investigated by standard PCR and automatic sequencing methods) was identified in lymphocytes isolated from peripheral blood, muscle biopsy and cultured skin fibroblasts. The mother and other maternal relatives are carriers for the same mutation. This case is unusual for age of onset, gender, associated neurological findings and evolution.

[Short-term effects of prone positioning on the oxygenation of pediatric patients submitted to mechanical ventilation]

OBJECTIVE: To analyze the short-term effects of prone positioning on the oxygenation of mechanically-ventilated children suffering from severe hypoxemia. MATERIALS AND METHODS: A prospective, nonrandomized trial (each patient as his/her own control) was conducted between July 1998 and July 1999. Mechanically-ventilated children with peak inspiratory pressure greater than or equal to 30 cm H(2)O, FiO(2) greater than or equal to 0.5, and PaO(2)/FiO(2) ratio less than or equal to 200 were included in the study. Each patient was kept in the prone position for two hours, returning to the supine position after this period. Oxygenation was assessed by means of PaO(2)/FiO(2) in the supine position (one hour before prone positioning), one hour after prone positioning, and one hour after returning to the supine position. Patients who presented an increase of at least 20 in PaO(2)/FiO(2) were considered responsive. The results were compared by Student t-test, Friedman test, chi-square test, Fishers exact test, and confidence interval. RESULTS: Eighteen children (10 males), whose mean age was 11.5 -/+11.5 months, with initial PaO(2)/FiO(2) of 96.06 -/+ 41.78, participated in the study. After one hour in the prone position, 27.7% of the patients (5/18) improved their PaO(2)/FiO(2) ratio (P=0.045). Six of these patients presented reduced lung compliance (four of them had acute respiratory distress syndrome); and twelve patients showed increased airway resistance (six of them presented bronchiolitis). No significant difference was observed between these two groups (reduced lung compliance x increased airway resistance) in terms of age, sex, duration of ventilation prior to change in position, peak inspiratory pressure, FiO(2), severity of hypoxemia, and outcome. CONCLUSION: Prone positioning during mechanical ventilation of children with severe hypoxemia may improve the PaO(2)/FiO(2) ratio in the first hour.

Cytogenetics of two species of Paratelmatobius (Anura: Leptodactylidae), with phylogenetic comments

In this paper we provide a cytogenetic analysis of Paratelmatobius cardosoi and Paratelmatobius poecilogaster. The karyotypes of both species showed a diploid number of 24 chromosomes and shared some similarity in the morphology of some pairs. On the other hand, pairs 4 and 6 widely differed between these complements. These karyotypes also differed in their NOR number and location. Size heteromorphism was seen in all NOR-bearing chromosomes of the two karyotypes. In addition, both karyotypes showed small centromeric C-bands and a conspicuous heterochromatic band in the short arm of chromosome 1, although with a different size in each species. The P. cardosoi complement also showed other strongly stained non-centromeric C-bands, with no counterparts in the P. cardosoi karyotype. Chromosome staining with fluorochromes revealed heterogeneity in the base composition of two of the non-centromeric C-bands of P. cardosoi. Comparison of the chromosomal morphology of these Paratelmatobius karyotypes with that of P. lutzii showed that the P. poecilogaster karyotype is more similar to that of P. lutzii than P. cardosoi. These cytogenetic results agree with the proposed species arrangements in the P. cardosoi and P. lutzii groups based on morphological and ecological data.

[Randomized clinical trial of intravenous magnesium sulfate versus salbutamol in early management of severe acute asthma in children]

OBJECTIVE: To study the efficacy of intravenous magnesium sulfate and intravenous salbutamol in the treatment of severe asthma in children. METHODS: Randomized, double-blind, placebo-controlled clinical trial, including children above 2 years of age with severe acute asthma admitted to the observation ward of the Pediatric Intensive Care Unit of Hospital São Lucas. All patients received conventional treatment (oxygen, corticoids, beta-adrenergics) on admission, and later received one of the following solutions: a) IVMg (50 mg/kg); b) intravenous salbutamol (1 micro g/kg); c) saline solution. Clinical assessments, electrolyte concentration, and arterial blood gas analyses were recorded before intravenous infusion and one hour after that. RESULTS: Fifty patients participated in this study (of whom 53% were females, mean age = 4.5 years). There were no significant differences among the three groups. The group that received IVMg presented lower blood pressure during administration, which reached normal levels one hour afterwards, along with an increase in serum magnesium (P<0,001) and serum pH, and reduction of PaCO(2). The group that received intravenous salbutamol had lower respiratory rate (P=0.05) and higher blood pressure (P=0.01), and one hour after administration, these patients showed decreased respiratory rate (P=0.02); lower levels of serum potassium (P=0.009); higher pH, and reduced PaCO(2). This group required fewer nebulizations (P=0.009), fewer nebulizations per day (P<0.001) and less oxygen therapy than the IVMg and placebo groups. Acidosis was more persistent (P<0.01) in the placebo group. No difference as to the length of hospital stay was observed in any of the three groups. Artificial ventilation was necessary in 10% of the patients. CONCLUSIONS: The early intravenous administration of magnesium sulfate, especially salbutamol, achieved a rapid clinical response with excellent prognosis and no significant side effects.

[Exogenous surfactant treatment for severe acute viral bronchiolitis: case report]

OBJECTIVE: To describe the possible clinical and laboratory effects of exogenous surfactant instillation into the tracheal tube of a child with severe acute bronchiolitis undergoing mechanical ventilation. CASE REPORT: a 2-month-old girl with clinical diagnosis of acute viral bronchiolitis underwent mechanical ventilation. She required high positive inspiratory peak pressure (35 to 45 cmH(2)O) and high inspiratory fraction of oxygen (FiO(2) = 0.9), but showed no clinical response or improvement in the arterial blood gas analysis. An exogenous surfactant (Exosurf(R), Glaxo - 50 mg/kg) was used to facilitate the use of a less aggressive ventilatory strategy. RESULTS: Four hours after surfactant administration, it was possible to reduce the positive peak inspiratory pressure (PIP) from 35 to 30 cmH(2)O, and FiO(2) from 0.9 to 0.6; and to increase the positive end-expiratory pressure (PEEP) from 6 to 9 cmH(2)O. During this period the paO(2)/FiO(2) ratio increased from 120 to 266. At the end of 24 hours, FiO(2) could be reduced to 0.4. DISCUSSION: Surfactant inactivation may be a decisive factor in the unfavorable evolution of some severe cases of acute bronchiolitis. The tracheal instillation of exogenous surfactant, in these cases, allows us to adopt less aggressive ventilatory strategies, and promotes rapid clinical responses.

Direct action of the biocide carbendazim on phenolic metabolism in tobacco plants

In view of the essential role of phenolic compounds in the development of pathogen resistance in plants, and given the influence that fungicides exert over phenolic metabolism, the aim of the present study was to determine the effect of the application of different rates of fungicide on the metabolism of phenolic compounds in tobacco plants (Nicotiana tabacum L. cv. Tennessee 86). The fungicide applied was carbendazim, with a purity of 100%, at three different rates: 1.3 mM (carb(1)), 2.6 mM (this being the recommended concentration, carb(2)), and 5.2 mM (carb(3)). The control treatment was without carbendazim. The results in relation to control plants indicate that the application of carb(1) in tobacco plants not afflicted by damaging biotic and abiotic agents boosts phenolic accumulation. Therefore, in the case of carbendazim, the application of 50% less (carb(1), 1.3 mM) than the recommended dosage (carb(2), 2.6 mM) of this fungicide could be more effective, because the foliar accumulation of phenolics presented at carb(1) may imply an increased resistance of plants to pathogen infection. On the other hand, we found an inhibition of the phenolic oxidation by the application of carbendazim, principally at carb(3). These results suggest that the excessive application of carbendazim (5.2 mM) could be harmful for healthy plants, because, on inhibiting phenolic metabolism (biosynthesis and oxidation), such treatment would also sharply reduce the capacity of these plants to respond against pathogen attack.

[Congenital syphilis: an emerging emergency also in Brazil]

OBJECTIVE: To highlight to the fact that some newborns are not identified as having congenital syphilis, and will present to an emergency room within a few months with a severe disease. METHOD: Review of the charts concerning 3 patients with congenital syphilis, as well as review of the literature using Medline and Lilacs databases, covering the period from 1988 to 1999. RESULTS: We describe the case of 3 infants whose diagnosis of congenital syphilis was only established after the neonatal period, when they presented to the emergency room and were admitted to the pediatric intensive care unit. The first patient had neurosyphilis and nephrotic syndrome, the second had neurosyphilis, and the third had hepatitis. We discuss the clinical aspects of the cases, and comment on other clinical manifestations of congenital syphilis that should be within the purview of pediatric emergency medicine. We analyze the reasons for the failure to diagnose syphilis at birth, and describe some risk factors for gestational syphilis. CONCLUSIONS: Considering the rising incidence of syphilis in Brazil, and the possibility that the congenital infections are not recognized at birth, emergency physicians must keep a high degree of suspicion and an awareness of maternal risk factors, prenatal serology pitfalls, as well as of the several clinical presentations of congenital syphilis that can develop in the first months of life.

[Shock therapy in children]

OBJECTIVE: Review the theoretical bases of the therapeutic approach for volumetric resuscitation of the infant in shock and the evolutionary process that take to the pharmacological support to the circulationMETHODS: References were obtained from computerized searches on the National Library of Medicine (Medline), recent review articles and personal files. RESULTS: Shock and septic shock is the leading cause of mortality in critically ill patients. The septic shock is an extremely complex disease process leading to progressive multiple organ failure. Its presentation may be subtle or catastrophic. Successful management depends on an understanding of the pathophysiology of the syndrome, allowing rapid, appropriate resuscitation. Treatment often requires aggressive correction of volume deficit, maintenance of adequate perfusion pressure with inotropic and vasopressor, mechanical ventilation and others therapies. CONCLUSIONS: The management of the shock in children presents a challenge for the pediatrician. Hemodynamic and respiratory instability should be anticipated. Management requires multisystemic and careful intervention.

[Acid-base balance disorders]

OBJECTIVE: Review the theoretical bases on the maintenance of the acid-basic balance, the pathophysiology of the disturbances and its therapeutics in the child.METHODS: References were obtained from computerized searches on the National Library of Medicine (Medline), recent review articles and personal files.RESULTS: Acid-basic disturbances are frequently found in critical ill children. Their pathophysiology and main causes are a complex and multifactorial process. The management depends on precocious diagnosis and of the understanding of the base cause. The treatment should be adjusted for each disturbance and its base cause. Frequently it requests an aggressive correction and continuous monitoring.CONCLUSIONS: The knowledge of the physiology of the acid-basic balance as well as the understanding of the pathophysiology of the main disturbances associated to the clinical situations represent a challenge for the pediatrician. The management of acid-basic balance demands appropriate and careful intervention.

[Respiratory failure in the child]

OBJECTIVE: To describe the main physiopathologic mechanism of the respiratory failure in the child, as well as to discuss some aspects of the differential diagnosis and treatment. SOURCE OF DATA: The main national and international textbooks and articles about respiratory failure in the child were used as sources of data for this research. RESULTS: Respiratory failure is defined as the incapacity to maintain a paO(2) over 50 mmHg associated or not to a paCO(2) over 50 mmHg in children breathing ambient air at sea level. This failure may be classified as hypoxemic or hypercapnic, or even as acute or chronic. The main alterations may be hypoventilation, ventilation perfusion mismatch and diffusion defect. It may be secondary to a central origin, upper or lower airway compromise, parenchyma disease, or due to pleural or thorax wall affection. The hypoxemia evaluation may be done by hemoglobin saturation, alveolar capillary gradient of oxygen (D[A-a]O(2)) or by the paO(2) / FiO(2) index. COMMENTS: The knowledge of the physiopathologic mechanisms that cause respiratory failure in the child is important to define the more efficient therapeutic strategy for each cause.

[Anaphylatic reactions to ant stings]

OBJECTIVE: Relate the occurrence of severe anaphylactic reactions caused by ant stings.METHODS: Case report of severe anaphylactic reaction caused by multiple ant stings, and revision of the literature (Medline and Lilacs). RESULTS: A male patient, white, 2 years-old, suffered multiple stings of small red ants of the species Solenopsis invictas, with the occurrence of severe anaphylactic reactions, and resulting in cortical blindness as a neurological sequel. CONCLUSIONS: The occurrence of such events, not very rare, should be taken in consideration by physicians, once such insects are common in our environment, and their sting can result, sometimes, in severe anaphylactic reactions.

[Autonomic dysfunction in Guillain-Barré Syndrome: a 13 year experience in pediatric intensive care unit]

The acute inflammatory demyelinating polyneuropathy (Guillain-Barré Syndrome) might have a severe presentation but a good prognosis in children. It is an immune-mediated and inflammatory disorder of the peripheral nervous system. This retrospective study observed that GBS is frequently complicated by hypertension and other autonomic disorders. Cardiovascular instability is due to the involvement of the autonomic nervous system and results in labile blood pressure, cardiac dysrhythmias and hypovolemia. During a 13-year period (1982-1995), 21 children were admitted to the Pediatric Intensive Care Unit of São Lucas Hospital, Porto Alegre, south of Brazil. Eight patients were mechanically ventilated. Symptoms of autonomic disturbance were frequently seen, especially in patients with severe clinical evolution. Previous investigations of the mechanism of hypertension associated with GBS did not evaluate the etiology of these phenomena. With modern pediatric intensive care support the deaths are rare. There is no death in this studied group.

[Decision making about the child in CIU--participation of the family]

This paper focuses attention on the moral and ethical principles in the treatment of a very sick newborn infant and child. Special attention is given to the risk benefit balance of the employment of sophisticated technology with the purpose of prolonging the survival of a possible handicapped child. The authors analyzed the different ways of facing this problem according to different cultural backgrounds. The concept of a terminal patient is not applied to the neonatal period. The principle of autonomy is discussed, and the familiar feelings are analyzed.