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Biomedical subjects

R M Nelson

Publications and source records attributed to R M Nelson.

At least 127 records · Page 7Linked to original sources
PubMed1983

Laser etched bifilar fine wire electrode for skeletal muscle motor unit recording.

To selectively record a limited number of skeletal muscle motor unit action potentials, a bifilar fine wire electrode was developed. Two 8 micrometers wires were braided together, a hook formed, and ends insulated. A round beam, pulsed laser, etched a 5 micrometers piece of insulation from each wire near the hooked end. Bipolar recordings from a select number of skeletal muscle motor units were obtained from these two uninsulated 5 micrometers areas. Reactive and capacitative components for each set of electrodes were measured. These electrodes were selective in recording from 3 to 5 single motor unit action potentials at low isometric tension levels.

Electrodes↗
PubMed1983

Comparison of skeletal muscle motor unit discharge characteristics in young and aged humans.

The purpose of this study was to determine the discharge characteristics of motor unit action potentials. Three decades of aged subjects ranging from 60 to 90 yr of age were compared to a group of 20-35 yr olds. Motor unit behavior was described by the interspike interval (ISI) and expressed statistically as a mean, a floating standard deviation (FSD), and a floating serial correlation (FRHO). The 70- to 79-yr-old group tended to have a slow motor unit discharge rate, an increased variability of discharge (FSD) and a negative serial correlation coefficient (FRHO). All three factors describing motor unit discharge behavior possibly suggest substitution of larger motor units for small motor units normally active at low tensions for the 70-79 age group.

Action Potentials↗
PubMed1983

Effects of routine care procedures on transcutaneous oxygen in neonates: a quantitative approach.

The changes in transcutaneous oxygen tension (TcPO2) during 123 observations of 10 care procedures were compared with the intrinsic variability of the TcPO2 at the time of the procedures. Standard deviations of the TcPO2 were measured by planimetry from continuous recording in undisturbed infants during a 10-minute control period immediately before each procedure. The decrement of TcPO2 during the procedure and the change in TcPO2 5 minutes after the procedure had ended were measured. A chest x-ray film had the most striking early hypoxic effect, but all the procedures produced early hypoxia in at least one-quarter of the infants. The significant decreases in oxygenation with particular procedures indicate areas in which changes in techniques might be applied to the benefit of the neonate.

Humans↗
PubMed1983

Ligation of patent ductus arteriosus in premature infants: importance of accurate anatomic definition.

The aortic arch anatomy of the premature infant may not be as simple to determine as the anatomy of an older child. A case of a premature infant who had inadvertent ligation of the left pulmonary artery during attempted ligation of a patent ductus arteriosus is described. On the fourth day following the initial operation, the patient underwent successful surgery to remove the pulmonary artery ligature and to ligate the persistent patent ductus arteriosus. A lung scan on the seventh day following removal of the pulmonary artery ligature showed normal perfusion of both lungs. Six months later, the child's growth, development, and chest roentgenogram were normal.

Aorta, Thoracic↗
PubMed1982

Elevated ornithine decarboxylase activity in the rat liver following exposure to halothane, enflurane and isoflurane.

Exposure of rats to the volatile anesthetics, halothane, enflurane and isoflurane and low FIO2 (0.8%) for two hours results in a transient induction of ODC appearing maximally four hours after exposure. Without the low oxygen accompanying the anesthetic or the low oxygen alone, no significant induction of ODC occurred. The concentration of anesthetic used to produce the ODC induction were 0.5% halothane, 1.5% enflurane and 1.4% isoflurane. Except for halothane, reducing the anesthetic concentration only slightly reduced the effect on ODC levels to control values. Reduction of halothane concentrations to 0.1% was required to reduce the values to control levels. Pretreatment of the animals with either cycloheximide or actinomycin D delayed the onset of ODC induction. The data support the fact that liver damage can occur in the absence of metabolism of the drug.

Aerobiosis↗
PubMed1982

Patent urachus complicating pregnancy: a review and report of a case.

A congenital abnormality of the urachus is extremely rare in pregnancy. We reviewed the English literature since 1877 and found only 12 case reports of urachal complications during pregnancy. Eight patients developed complications from a urachal cyst or sinus, and four patients had a patent urachus with urinary fistula. We report an additional case of a patent urachus which uniquely presented for the first time during pregnancy with urinary drainage from the umbilicus. Urodynamic changes in pregnancy which may have produced this complication are discussed. Abdominal wall ultrasonography is extremely helpful in the diagnostic evaluation of suspected urachal tract complications during pregnancy.

Adult↗
PubMed1981

Strength-duration curve: intrarater and interrater reliability.

The purpose of this study was to determine the coefficients of correlation for intrarater and interrater reliability for producing the strength-duration curve. The intrarater reliability curve was determined by a test-retest by the same examiner within a one-week interval. The interrater reliability was determined by using two examiners, each testing and recording his own results on the same subject within the same hour. The tibialis anterior muscle was tested in 24 healthy men. The interrater coefficients of correlation of 11 pulse durations of the strength-duration curve ranged from r = .979 to r = .771 (mean r = .945). The intrarater reliability coefficients ranged from r = .850 to r = .394 (mean r = .541). Both mean coefficients were statistically significant at p less than .01. The variance interpretation of the correlation coefficient data revealed that intrarater coefficients were not highly consistent (r(2) = .29). Interrater coefficients interpreted by variance estimates tended to be consistent (r(2) = .89). We believe that normal physiologic variation in the human subject was the cause of low intrarater values. The necessity of developing a normalized strength-duration curve is discussed.

Adult↗
PubMed1980

Ischemic papillary muscle necrosis in stressed newborn infants.

The recent association of transient tricuspid insufficiency in newborn infants with ischemic papillary muscle necrosis prompted a detailed retrospective clinical and histologic analysis of autopsied infants who died within seven days of birth between 1973 and 1977. Infants with congenital heart disease, erythroblastosis fetalis, and known congenital viral infections were excluded. Thirty-one of 82 infants had at least one site of ischemic myocardial necrosis: 11 had lesions only in the right ventricle, 13 had lesions only in the left ventricle, and seven had bilateral lesions. The apical region of an anterior papillary muscle was the most common site. IMN occurred more commonly in older, larger infants. Asphyxia at birth, a murmur of atrioventricular valve insufficiency, and signs of congestive heart failure correlated well with the presence of IMN, but few other perinatal events predicted its occurrence. This report suggests that IMN is a common event in stressed infants who die early in life and probably is related to episodic hypoperfusion of the myocardium.

Apgar Score↗
PubMed1980

Effects of elbow position on motor conduction velocity of the ulnar nerve.

The purpose of this study was to evaluate the ability of the ulnar nerve motor axons to conduct an evoked action potential at three elbow positions (0 degrees, 90 degrees, and 120 degrees). The latency (from above and below elbow), negative-phase amplitude, and duration of the evoked action potential were used to evaluate the effect of elbow position on 50 normal men. The results indicate that latency of the response, negative-phase amplitude, and duration of the evoked action potential did not vary with the elbow position. Clinical implications for the performance of motor nerve conduction studies for the ulnar nerve are presented. Suggestions for arm position during the motor nerve conduction studies are included.

Adolescent↗
PubMed1980

Family-acquired respiratory disease in high-risk infants.

Five infants who had been patients in the same Neonatal Intensive Care Unit (NICU) were readmitted with respiratory illness. The illness was characterized by cough, congestion, apnea, and infiltration of the lungs revealed by radiographic examination. Only one infant was febrile. All five patients recovered; however, one infant required prolonged intubation and mechanically assisted ventilation. Investigation revealed that the illness was associated with prematurity and contact with ill family members. Illness was not associated with exposure to ill personnel in the NICU, low birth weight, or previous lung disease. This outbreak demonstrates the dangers involved in sending premature infants home when respiratory illness is prevalent in the family.

Cross Infection↗
PubMed1980

Lung solute permeability and lung liquid absorption in premature ventilated fetal goats.

In 21 premature fetal goats ventilated at low tidal volumes, measurements were made of alveolar surfactant activity by bubble stability tests on alveolar liquid, lung epithelium solute permeability using radiolabeled tracer molecules, lung liquid absorption from wet and dry lung weights, effectiveness of lung gas exchange, and lung mechanics. Arterial pO2 and residual gas volume were higher and arterial pCO2 and specific compliance were lower in animals whose bubble stability test was greater than 1:5 on alveolar liquid aspirated following one hr of ventilation. Animals without detectable surfactant in fetal lung liquid before ventilation had transfer of all size tracer solutes between alveolar liquid and blood, whereas those with detectable surfactant did not allow tracers 14 A or larger in radius to cross the lung epithelium. Lung liquid absorption rate in animals without lung liquid surfactant in fetal lung liquid before ventilation averaged 25% hr, whereas those with surfactant absorbed liquid at only 2%/hr in this protocol. All differences in solute permeability and lung liquid absorption were related to preventilation surfactant levels in fetal lung liquid, and not to postventilation surfactant levels or to lung function.

Absorption↗
PubMed1980

Oligohydramnios and transient neonatal anuria: a possible association with the maternal use of prostaglandin synthetase inhibitors.

The chronic use of prostaglandin synthetase inhibitors is reported in a pregnant patient with severe juvenile rheumatoid arthritis. Aspirin and indomethacin, along with corticosteroids, were required to prevent significant progression of the disease. Pregnancy was complicated by oligohydramnios and intrauterine growth retardation. The infant suffered transient anuria. The effects of prostaglandin synthetase inhibitors on renal vascular function is reviewed, and a possible association between the chronic ingestion of these drugs and compromised renal function in the newborn is pointed out.

Adult↗
PubMed1980

Timing of postpartum hematocrit determinations.

Postpartum hematocrit determinations have been done at eight, 16, and 24 hours after vaginal deliveries. We studied 23 patients in whom the hematocrit level dropped at least 10% from control value with a range of 10% to 32%. The peak drop in hematocrit occurred at eight hours in four patients, at 16 hours in nine patients, and at 24 hours in ten. Therefore, no single timed hematocrit determination in the first 24 hours post partum will detect the peak drop in a vast majority of patients. A proposed plan for timing of hematocrit determinations in the postpartum period is presented.

Female↗
PubMed1980

Developmental outcome of premature infants treated with theophylline.

The methylated xanthines are known to have multiple metabolic effects. This study was performed to examine the development of premature infants treated with theophylline in the neonatal period for apnea. The theophylline-treated infants had lower Apgar scores and gestational ages when compared to those who did not receive theophylline. There were no significant differences in the developmental indices, and both groups had similar incidences of severe neurologic sequelae and retrolental fibroplasia. Similarly, there were no differences in the somatic growth. The data suggest that theophylline does not adversely affect development of premature infants when examined at 9--27 months of age.

Apnea↗