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Biomedical subjects

J M Lopes

Publications and source records attributed to J M Lopes.

At least 91 records · Page 5Linked to original sources
PubMed1986

Analysis and comparison of the internal promoter, pE, of the ilvGMEDA operons from Escherichia coli K-12 and Salmonella typhimurium.

It was previously determined that the distal portion of the ilvGMEDA operon was expressed despite the insertion of transposons into ilvG and ilvE. This observation suggested the existence of internal promoters upstream of ilvE (pE) and ilvD (pD). The internal promoter pE, responsible for part of ilvEDA expression, has been analyzed both in vivo and in vitro. Our results indicate that: pE exists in both E. coli K-12 and S. typhimurium; pE is located in the distal end of the ilvM coding sequence; the pE sequence is highly conserved in the two bacteria; the amino acid sequence of the ilvM gene product is 93% homologous between the two bacteria; transcription from pE can be demonstrated both in vivo and in vitro; the efficiency of pE is essentially equivalent in the two bacteria.

Chromosome Mapping↗
PubMed1985

[Focal epithelial hyperplasia (Heck disease)].

A case of focal epithelial hyperplasia (Heck's disease) in a nine years old caucasian girl is described. The disease is characterized by multiple flat verruca like elevations of the oral mucosa. The histological findings were acanthosis and papillomatosis with elongated anastomosing rete ridges. We also observed vacuolated cells with a hypercromatic marginated nucleo. In this paper the etiology is also discussed and we agreed that focal epithelial hyperplasia is an HPV, induced disease. Local application of vitamin A acid for three months was unsuccessful.

Animals↗
PubMed1983

Effect of caffeine on skeletal muscle function before and after fatigue.

We studied the effect of caffeine on voluntary and electrically stimulated contractions of the adductor pollicis muscle in five adult volunteers. Caffeine (500 mg) was administered orally in a double-blind fashion. Electrical stimulation of the ulnar nerve was performed at 10, 20, 30, 50, and 100 Hz before and after a sustained voluntary contraction held at 50% of the maximal voluntary contraction (MVC). A brief tetanus at 30 Hz was also performed to calculate relaxation rate in the fresh muscle. Contractile properties, relaxation rate, and endurance were then assessed after caffeine and placebo, as well as the response of the fatigued muscle to different frequencies of stimulation. There was no difference in the maximal tension obtained with electrical stimulation (T100) or in the MVC between placebo and caffeine. The tensions developed with electrical stimulation at lower frequencies increased significantly with caffeine ingestion, shifting the frequency-force curve to the left, both before and after fatigue. Mean plasma caffeine concentration associated with these responses was 12.2 +/- 4.9 mg/l. We conclude that caffeine has a direct effect on skeletal muscle contractile properties both before and after fatigue as demonstrated by electrical stimulation.

Adult↗
PubMed1983

Influence of chest wall distortion on esophageal pressure.

The caudocephalad profile of esophageal pressure swings was studied in 10 preterm and 5 full-term infants, and the effect of chest wall distortion on esophageal pressure swings was analyzed in 12 preterm infants. Esophageal pressure was measured with a fluid-filled catheter, tidal volume with a pneumotachograph, mouth pressure with a face mask and pressure transducer, and rib cage and abdominal motion with magnetometers. In preterm infants the profile of esophageal pressure swings fell very steeply in the caudocephalad direction. In full-term infants it was flat during quiet sleep and steep during rapid-eye-movement sleep. When breaths, standardized for pleural pressure, were compared between a period with maximal and a period with minimal chest wall distortion, esophageal pressure swings for both spontaneous and occluded breaths were higher in the former period. We conclude that the complaint preterm rib cage results in an uneven distribution of pleural pressure and that this distribution varies with changes in chest wall distortion. Esophageal pressure measurements are therefore an unreliable estimate of mean pleural pressure in the preterm infant and can be unreliable in the term infant.

Esophagus↗
PubMed1983

Effect of chest wall distortion on occlusion pressure and the preterm diaphragm.

We studied the effect of chest wall distortion (CWD) on transdiaphragmatic pressure (Pdi) and/or mouth pressure during end-expiratory airway occlusions in seven preterm infants. We measured mouth occlusion pressure (Pmo) with a face mask and pressure transducer, gastric pressure (Pga) with a fluid-filled catheter, diaphragmatic electromyogram (Edi) using surface electrodes, and rib cage and abdominal motion using magnetometers. We reasoned that Pdi = Pmo - Pga on airway occlusion. Periods with maximal and periods with minimal CWD were compared. We found that 1) when CWD was minimal, an increase in Edi produced an increase in Pmo and Pdi in all infants; when CWD was greatest, large increases in Edi produced no increase in Pmo or Pdi in four infants; 2) when breaths with the same Pmo or Pdi from each period in each infant were compared, those from the period with greatest CWD had an increased Edi (mean increase 76%, P less than 0.005, and 144%, P less than 0.01, for Pmo and Pdi, respectively). We conclude that in preterm infants, Pmo can be a poor indicator of respiratory drive, and CWD markedly limits the effectiveness of the diaphragm as a force generator.

Diaphragm↗
PubMed1981

Synergistic behavior of inspiratory muscles after diaphragmatic fatigue in the newborn.

We studied diaphragmatic and intercostal muscle activity and the pattern of motion of rib cage and abdomen after diaphragmatic muscle fatigue in 15 newborn infants (birth wt 1,251 +/- 424 g, mean +/- SD). Rib cage and abdominal motion were monitored with magnetometers and intercostal and diaphragmatic electromyograms (EMG's) with surface electrodes. Twelve infants showed a total of 66 episodes of muscle fatigue identified by EMG frequency spectrum analysis. Two patterns of responses to fatigue were observed. In the first case, five infants consistently recruited their intercostal muscles; this was followed by a normalization of the diaphragmatic frequency spectrum. In these infants, recruitment of intercostal muscles successfully prevented any clinical deterioration. In the second, seven infants showed no change in their intercostal muscle activity, and diaphragmatic fatigue was followed by apnea. We conclude that in newborn infants the synergistic behavior of the diaphragm and intercostal muscles can maximize the performance of these muscles and, in some infants, seems to prevent development of apnea.

Apnea↗
PubMedDate not supplied

[Normal neonatal cerebral ultrasonography in preterm infants - Is it possible to calm down the parents?]

OBJECTIVE: To verify the predictive values of neonatal cerebral ultrasonography for motor and cognitive development of very low birth weight preterm babies after twelve months correct age. METHODS: The population studied was a cohort of preterm babies with birth weight less than 1,500g, who had been admitted in the Neonatal Intensive Care Unit of Instituto Fernandes Figueira, and were followed to 12-30 months corrected age for prematurity. A cerebral ultrasonography was performed before discharge. The results were classified as normal and abnormal (parenchymal hemorrhage, porencephaly, periventricular leucomalacia, ventricular dilatation). The babies were followed in the Follow-up Clinic and between 12-30 months correct age they underwent a neurological assessment with observation of the acquisition of motor milestones and submitted to Bayley Scales of Development. RESULTS: We studied 83 babies. Cerebral ultrasonography was normal in 68 babies (81.9%) and abnormal in 15 (18.8%). With a mean age of 21 months, 63 children (75.9%) had normal motor development and 20 (24.0%) had motor abnormalities. The cognitive development was normal in 68 children (81.9%). The negative predictive value of the cerebral ultrasonography for motor development was 85.3%, and for cognitive development, 86.8%. The positive predictive value of the cerebral ultrasonography for motor development was 66.7% and for cognitive development, 42.9%. CONCLUSIONS: The negative predictive values were greater than the positive predictive values in both areas of development. The probability for children with normal neonatal ultrasonography to have normal motor and cognitive development is greater than 85%.

Journal Article↗
PubMedDate not supplied

[Joint effort to improve quality in a Brazilian pediatric public hospital through cross-infection control]

OBJECTIVES: To examine the role of the laboratory in nosocomial infection control from January 1993 to December 1996 in Centro Geral de Pediatria of Hospital Foundation of Minas Gerais state. METHODS: Follow -up of 101,139 patient-days (11,147 discharges + deaths + transfers) in the wards and intensive care unit by using the National Nosocomial Infection Surveillance (NNIS) system proposed by the Centers for Disease Control and Prevention (CDC- Atlanta). Prospective surveillance of nosocomial infections at all sites was performed according to the hospital - wide (since 1992) and intensive care unit (since 1996) NNIS components. The CDC definitions since 1988 and Brazilian Ministry of Health regulation number 930 since 1992 were used to diagnose the nosocomial infections. RESULTS: The five most frequent nosocomial pathogens (from a total of 139 isolates) were Klebsiella sp = 24.5%; S. aureus = 18%; P. aeruginosa = 13.7%; E. coli = 12.9%; S. epidermidis = 12.2%. The percentage of identification of pathogens isolated from nosocomial infection sites has increased from 6.2% in 1993 to 13.3% in 1995 and 28.2% in 1996 (p< 0.001) and so has the attempt to isolate the pathogens: 7.5% in 1993, 16.1% in 1995, 33.8% in 1996 (p< 0.001). The time interval taken for lab results (from specimen collected to microbiology result) has decreased from the average of ten days in 1993 to six days in 1996 (p = 0.001). CONCLUSIONS: The continuing education and improved communication among infection control personnel, pediatricians, surgeons and members of the laboratory have proven to play a key role in the epidemiology of nosocomial infections by defining their etiologies in the Centro Geral de Pediatria. A task force to determine the microbiology has been achieved by the understanding of all clinicians that it is important to treat their patients specifically. The NNIS method applied to Brazilian hospitals has shown its impact on the microbiology lab role in nosocomial infection control as well.

Journal Article↗
PubMedDate not supplied

[Nitric oxide in the treatment of neonatal pulmonary hypertension].

This study describes the effects of nitric oxide in newborns with persistent pulmonary hypertension. We studied 9 infants with severe respiratory failure characterized by hypoxemia and pulmonary hypertension. All infants met ECMO criteria and the oxygenation index (OI) was greater than 25. Mean birth weight was 2698 -/+ 661 g and gestational age was 36.4 -/+ 2.6 weeks. Nitric oxide was administered in a Y circuit in the inspiratory line of the mechanical ventilator. Nitric oxide and NO2 concentrations were monitored with electrochemical analyzers (PACI and PACII-Draeger). Pulmonary hypertension was diagnosed with clinical and echocardiografic criteria, with detection of right to left shunt with color doppler. All patients showed a dramatic improvement in oxigenation after nitric oxide administration. The drug reduced the mean OI, which was 48.5 before its administration, to 17.7 after 30', 14.1 after 6 hours, and 10.5 after 12 hours. We observed in all patients a reduction in pulmonary vascular resistance, reversal of the right to left shunt without any effects on systemic arterial pressure. Metahemoglobin levels did not reach 1.5% in any patient. Only one out of the 9 patients died, after reversal of the pulmonary hypertension, from other complications of perinatal asphyxia. Our data show that nitric oxide is a promising drug in the treatment of neonatal pulmonary hypertension and that it may reduce the need of ECMO in severe respiratory failure.

English Abstract↗
PubMedDate not supplied

[Single x double phototherapy for the treatment of hyperbilirubinemia in high risk newborn infants].

This is a randomized, prospective, controlled study to compare the efficacy of single versus double halogen phototherapy in high risk patients admitted to a newborn intensive care unit. Eighty patients were allocated to receive single (N=43) or double (N=37) phototherapy. The groups were similar in clinical and laboratory characteristics. Total serum bilirubin (SB), hematocrit and total serum protein were assessed by microanalysis prior to the beginning of the study and at 6, 12, 18 and 24 hours of treatment. The percent decline of SB was significantly higher in the double phototherapy group. This difference is first noted at 12h of treatment (10% vs 1.8%, p< 0.01) and is acentuated at the end of the study (19.4% vs 1.6%, p< 0.0001). Weight loss, variations in the hematocrit and total serum protein were similar in both groups. Cutaneous rash and temperature instability were not noted among the patients studied.Our results demonstrate that double phototherapy is more efficient than single phototherapy in treating hyperbilirubinemia in high risk newborn infants.

Clinical Trial↗
PubMedDate not supplied

[Surfactant replacement therapy: a multicentric trial comparing two dosage approaches].

This is an interim analysis of a multicentric trial that took place in 7 Neonatal Units to compare two initial doses of exigenous pulmonary surfactant (100 mg/kg and 200 mg/kg of phospholipids)by using a porcine surfactant for the treatment of very severe Hyaline Membrane Disease. The initial higher dose produced better oxigenation of arterial blood, reducing the time in high oxygen concentrations,while retreatments were necessary in less than half of the infants receiving 200 mg/kg as initial dose. The protocol of this study allowed the administration of additional doses only when FiO(2) was equal or greater than 0.40 instead of > 0.21, as in a large study recently published, where the same initial doses were given. This resulted in more than 40% reduction in the amount of surfactant administered,with apparently similar clinical outcome.

English Abstract↗
PubMedDate not supplied

[Pulmonary mechanics in the full-term newborn].

The objective of this study is evaluate the pulmonary function in full term newborn infants, comparing classic with non-invasive techniques. We describe the pulmonary function laboratory and software developed at Instituto Fernandes Figueira. We studied 10 healthy full-term newborn infants (birthweight 3.260 g + - 460 g) Occlusions were performed at inspiration end and during expiration which allowed us to calculate values for total pulmonary resistance (TPR) and total pulmonary compliance (TPC). Esophageal pressure was measured with a water filled catheter positioned in the lower third of the esophagus, to obtain lung resistance (RL) and compliance (CL). All signals were digitized at 60 Hz into a microcomputer for further analysis. Mean results of our study are: CL= 1.78 + - 0.36 ml/cm H(2)O/kg, TPC= 1.12 + - 0.27 ml/cm H(2)O/kg and TPR= 16 + - 4 cm H(2)O/l/seg/kg. Our values are very similar to the ones in the current literature.

English Abstract↗