Total intravenous anesthesia with propofol in pediatric patients outside the operating room.
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Anesthesiology↗
Biomedical subjects
L D Martin
Publications and source records attributed to L D Martin.
How the door opened: the peopling of the New World.
The timing, pathways, and number of migrations involved in the early peopling of the New World are examined from a variety of perspectives. Ultimately, the occupation of the Western Hemisphere was a direct result of boreal cultural adaptations in the Old World. Here, we discuss (1) the dates of appearance of these boreal cultural adaptations and their relevance to the peopling of America, (2) archeological and linguistic evidence bearing on the earliest peopling of the New World, (3) ecological and linguistic evidence on two alternative routes into the New World, and (4) the assumptions present in various migration models. The relative strengths of opposing hypotheses are analyzed by observing whether different approaches point to the same answers.
Anthropology, Cultural↗
Anesthesia and glucose-6-phosphate dehydrogenase deficiency in a child with congenital heart disease.
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Anesthesia, Intravenous↗
Permanent rescue of a non-Mendelian mutation of Paramecium by microinjection of specific DNA sequences.
The mutant Paramecium tetraurelia cell line d48 is unable to express the serotype A protein on its surface. Although the A gene is intact in the micronuclei of d48, the A gene copies in the macronucleus contain a large deletion eliminating virtually the entire coding sequence. Previous studies showed that microinjection of a plasmid containing the entire A gene into the macronucleus of d48 permanently restored A expression after autogamy. Together with other data, this result suggests that in wild type cells the A gene in the old macronucleus ensures the presence of a cytoplasmic factor that prevents A gene deletions at autogamy. In d48, where there are few, if any copies of the intact A gene in the old macronucleus, deletions occur during macronuclear formation. To elucidate the specific molecular mechanisms involved in this unusual phenomenon, we attempted to define the region(s) of the A gene necessary for rescuing d48. We show that microinjection of a 4.5-kb internal A gene fragment is sufficient for proper processing at autogamy and leads to permanent rescue of d48; i.e., the rescued strain is indistinguishable from wild type. Thus, rescue of d48 does not require upstream transcriptional control sequences, intact A mRNA or A serotype protein. We also show that various fragments of the A gene have the ability to rescue d48 to different extents, some being more efficient than others. We find no evidence to suggest that the A gene gives rise to a small stable RNA that might act as or encode a cytoplasmic factor. Molecular mechanisms that may be involved in the rescue of d48 are discussed.
Animals↗
Airway pressure release ventilation in a neonatal lamb model of acute lung injury.
OBJECTIVE: To determine if airway pressure release ventilation (APRV) is feasible in a neonatal animal model with acute lung injury. DESIGN: Nonrandomized, repeated, bracketed measures. SETTING: University research laboratory. SUBJECTS: Seven neonatal sheep (5.6 +/- 0.6 kg), less than 10 days of age. INTERVENTIONS: Acute lung injury was induced by oleic acid infusion and cardiorespiratory profiles were compared during spontaneous ventilation at ambient airway pressure, continuous positive airway pressure (CPAP), APRV, and conventional positive-pressure ventilation (PPV). MEASUREMENTS AND RESULTS: Oleic acid resulted in acute lung injury with stable cardiorespiratory status during the 3-hr study period. Mean airway pressure (Paw) was comparable for all three positive-pressure modes (CPAP 13.4 +/- 1.5, APRV 13.5 +/- 1.4, PPV 13.9 +/- 1.4 cm H2O, NS). After acute lung injury, CPAP increased arterial oxygenation compared with spontaneous ventilation (77.3 +/- 6.9 vs. 57.7 +/- 4.2 torr [10.3 +/- 0.9 vs. 7.7 +/- 0.6 kPa], p less than .05), and this increase was maintained during APRV (73.3 +/- 5.6 vs. 77.3 +/- 6.9 torr [9.8 +/- 0.7 vs. 10.3 +/- 0.9 kPa], NS). Alveolar ventilation was increased by APRV compared with CPAP (PaCO2 29 +/- 1 vs. 41 +/- 2 torr [3.9 +/- 0.1 vs. 5.4 +/- 0.3 kPa], p less than .05) without impairment of cardiovascular performance (cardiac output 1.18 +/- 0.16 vs. 1.20 +/- 0.17 L/min, NS). To achieve ventilation equivalent to APRV during PPV, peak Paw was greater (36.4 +/- 3.2 vs. 19.7 +/- 1.7 cm H2O, p less than .05) and cardiac output (0.94 +/- 0.11 vs. 1.18 +/- 0.16 L/min, p less than .05) and mean arterial pressure (91 +/- 7 vs. 96 +/- 6 mm Hg, p less than .05) were decreased during PPV compared with APRV. CONCLUSIONS: In this neonatal laboratory model of acute lung injury, APRV maintained oxygenation and augmented alveolar ventilation compared with CPAP. Compared with PPV, APRV provided similar ventilation and oxygenation, but at lower peak Paw than PPV, without compromising cardiovascular performance.
Animals↗
Ketamine by continuous infusion for sedation in the pediatric intensive care unit.
ICU physicians generally rely on either narcotics or benzodiazepines to provide analgesia and sedation. We describe five patients in whom ketamine administered as a bolus dose of 0.5 to 1.0 mg/kg, followed by a continuous infusion of 10 to 15 micrograms/kg.min, provided effective sedation and analgesia without significantly compromising cardiorespiratory function. Four of these patients previously experienced deleterious cardiorespiratory effects from either benzodiazepines or narcotics. In three patients who were breathing spontaneously, PaCO2 remained less than 44 torr during the ketamine infusion. With ketamine, no reduction in mean arterial pressure from baseline was noted in any patient. As with any form of iv anesthesia, ketamine can have cardiorespiratory side-effects; therefore, the means to manage these effects should be readily available.
Adolescent↗
Inspiratory work and response times of a modified pediatric volume ventilator during synchronized intermittent mandatory ventilation and pressure support ventilation.
Volume ventilation by demand flow ventilators significantly increases work of breathing during inspiration. Although various ventilator modifications and different modes of ventilation have been developed, there have been few studies regarding imposed work of breathing in infants and children. This study was designed to evaluate several modifications of a commercially available demand flow ventilator designed to shorten response time (tr) and decrease the imposed work (Wi) involved in opening the demand valve. Minimum withdrawal volume (Vmin), maximum negative pressure (P mneg), and tr were measured. Wi was defined as the product of Vmin and P mneg. Seven Siemens Servo 900C ventilators were tested under 16 different trial conditions with four variables: 1) mode of ventilation (synchronized intermittent mandatory ventilation [SIMV] vs. pressure support ventilation [PSV]); 2) caliber of circuit tubing (adult vs. pediatric); 3) location of airway pressure monitor (distal vs. proximal); and 4) ventilator trigger sensitivity (0 cm H2O--high vs. -2 cm H2O--low). Vmin, Pmneg, and Wi were all decreased (P less than .05) while tr was unaffected by changing ventilator trigger sensitivity from low to high. Wi was decreased by pediatric tubing and proximal airway pressure monitoring only when low trigger sensitivity was used. PSV and proximal airway monitoring shortened tr. The authors conclude that the use of pediatric circuit tubing and proximal airway pressure monitoring with a Siemens Servo 900C ventilator significantly improved ventilator performance.
Adult↗
Pentobarbital attenuates pulmonary vasoconstriction in isolated sheep lungs.
Pentobarbital sodium is a widely used anesthetic agent that has been demonstrated to attenuate systemic vascular responses to multiple pressors. To determine whether pentobarbital affected pulmonary vasoreactivity we determined the pulmonary vascular response to hypoxia and potassium in isolated in situ perfused sheep lungs. The flow resistive characteristics of the pulmonary vasculature were assessed by determining mean instantaneous pressure-flow relationships over a wide range of flows (20-120 ml.min-1.kg body wt-1) with PIO2 of 200 and 30 Torr, with and without pentobarbital. Pentobarbital attenuated hypoxic pulmonary vasoconstriction (P less than 0.001) in a concentration-dependent fashion (50% effective concentration = 0.42 mM). In addition, the pulmonary constrictor response to potassium was markedly blunted by pentobarbital (P less than 0.001). We conclude that pentobarbital inhibits hypoxic pulmonary vasoconstriction in a concentration-dependent fashion and that this inhibition of pulmonary vasoconstriction in isolated sheep lungs is not specific for hypoxia.
Animals↗
Resistance plasmids of Pasteurella multocida isolated from turkeys.
From 1940 through 1978, fifty-eight strains of Pasteurella multocida (serotype 3) were isolated from turkeys throughout the United States and were examined for R-plasmids. Forty-one of the isolates contained plasmid DNA, of which 7 isolates were found to encode resistance to tetracycline, streptomycin, and sulfonamides, or to streptomycin and sulfonamides. The R-plasmids were 2 to 10 megadaltons, nonconjugal, and contained a moles percent guanine plus cytosine ratio in the range of 57 to 61. The R-plasmids did not belong to any of the 19 incompatibility groups evaluated, including Inc Q. Digestion with restriction endonuclease indicated that 2 of the plasmids from P multocida isolated in 1960 and 1962 were identical, whereas 4 of the 5 plasmids obtained from P multocida isolated after 1966 were identical, with the 5th plasmid closely related to the other 4. The results indicated that R-plasmids were not widely dispersed among P multocida (serotype 3) isolated from turkeys in the United States. The nontransmissible nature of these plasmids was probably the major reason for their lack of dissemination.
Animals↗
Susceptibility of equine bacterial isolates to antimicrobial agents.
In vitro antimicrobic susceptibility patterns of commonly isolated aerobic gram-positive and gram-negative bacterial pathogens of equine origin were determined, using the agar-plate dilution method. All organisms were recent clinical isolates and included Corynebacterium (Rhodococcus) equi, Corynebacterium pseudotuberculosis, (coagulase positive) Staphylococcus sp, Streptococcus equi, Streptococcus zooepidemicus, Actinobacillus sp, Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Salmonella. In vitro susceptibility levels were outlined for 14 antimicrobics as follows: amikacin less than or equal to 4.0 micrograms/ml, ampicillin less than or equal to 1.0 microgram/ml, amoxicillin less than or equal to 1.0 microgram/ml, cefadroxil less than or equal to 8.0 micrograms/ml, chloramphenicol less than or equal to 8.0 micrograms/ml, erythromycin less than or equal to 1.0 microgram/ml, gentamicin less than or equal to 2.0 micrograms/ml, kanamycin less than or equal to 4.0 micrograms/ml, penicillin less than or equal to 1.0 microgram/ml, tetracycline less than or equal to 1.0 microgram/ml, sulfadimethoxine less than or equal to 10.0 micrograms/ml, ormetoprim/sulfadimethoxine less than or equal to 0.5/9.5 micrograms/ml, sulfadiazine less than or equal to 10.0 micrograms/ml, and trimethoprim/sulfadiazine less than or equal to 0.5/9.5 micrograms/ml.
Aerobiosis↗
Rapid detection of Salmonella spp. by using Felix-O1 bacteriophage and high-performance liquid chromatography.
A method is described whereby the presence of Salmonella spp. can be detected within 8 to 24 h of sample collection. The method depends upon the interaction of Salmonella spp. with the Salmonella-specific Felix-O1 bacteriophage. This interaction results in an increase in concentration of the bacteriophage which is detected by high-performance liquid chromatographic techniques.
Bacteriological Techniques↗
Detection of Salmonella spp. in milk by using Felix-O1 bacteriophage and high-pressure liquid chromatography.
A method is described whereby the presence of less than five salmonellae was detected per milliliter of milk within 24 h of sample collection. Salmonellae were removed from milk by means of electropositive large-pore filters. Eluates from the filters were analyzed for the presence of Salmonella spp. by Felix-O1 bacteriophage and high-pressure liquid chromatographic techniques. The method gave only a positive response when salmonellae were present in the milk. Of the serotypes and strains of Salmonella spp. tested, Salmonella dublin (10 strains), Salmonella typhimurium (5 strains), Salmonella anatum, Salmonella krefeld, and Salmonella saint-paul gave positive responses. One strain of Salmonella agona (three strains tested) and three strains of Salmonella enteritidis (seven strains tested) were not detectable by the method described herein.
Animals↗
Plasmid-mediated antimicrobial resistance in Haemophilus pleuropneumoniae.
Haemophilus pleuropneumoniae, isolated from the lungs of pig, was resistant to ampicillin, streptomycin, and sulfadiazine. This isolate, SD-1, possessed 1 plasmid (pVM105) coded for resistance to ampicillin and sulfadiazine, and the other (pVM104) for resistance to streptomycin and sulfadiazine. A 2nd isolate of H pleuropneumoniae, SD-2, recovered from a pig in a different outbreak of porcine pleuropneumonia, was resistant to streptomycin and sulfadiazine. These resistance determinants were on 1 plasmid (pVM106). All 3 patients were nontransmissible and small (pVM105 = 3.6 x 10(6) daltons, pVM104 and pVM106 = 2.3 x 10(6) daltons. The basis for resistance to ampicillin, encoded on plasmid pVM105, was due to a beta-lactamase. This beta-lactamase was highly active on penicillin G and ampicillin, moderately active on cephalothin, and inactive on oxacillin, indicating a TEM type of beta-lactamase.
Ampicillin↗
Conjugal transfer of an R-plasmid in Pasteurella multocida.
A strain of Pasteurella multocida isolated from turkeys during an outbreak of septicemic disease (fowl cholera) was shown to possess the ability to transfer streptomycin and sulphadiazine resistance to P. multocida and to Escherichia coli by conjugation. The genes necessary for the transfer of the resistance genes appeared to be associated with a plasmid of molecular weight 28.5 x 10(6). The resistance genes were shown to be associated with a second plasmid of molecular weight 7.2 x 10(6).
Conjugation, Genetic↗
New look at the origin of birds and crocodiles.
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Alligators and Crocodiles↗
Antibacterial activity of 9(S)-erythromycylamine-aldehyde condensation products.
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Aldehydes↗
Brainstem gangliogliomas.
Gangliogliomas are rare neurogliogenic tumors of the central nervous system. Primary involvement of the brainstem is characterized by variable presentations and a long clinical course before diagnosis. Identification of this group of tumors is essential because clinical improvement and prolonged survival have been documented following partial surgical resection.
Brain Stem↗