Lights out! A preventable complication of endotracheal intubation.
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Adult↗
Biomedical subjects
J D Johnson
Publications and source records attributed to J D Johnson.
Surgical management of splenic abscess in endocarditis.
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Abscess↗
Septoplasty complicated by staphylococcal spinal osteomyelitis.
Surgery for correction of anatomic abnormalities of the nasal septum is usually free of major infectious complications. A case of staphylococcal spinal osteomyelitis as a consequence of bacteremia induced by nasal septoplasty is reported and the questions raised by this occurrence are discussed.
Adult↗
Transient kinetic analysis of turnover-dependent fluorescence of 2',3'-O-(2,4,6-trinitrophenyl)-ATP bound to Ca2+-ATPase of sarcoplasmic reticulum.
The fluorescence of 2',3'-O-(2,4,6-trinitrophenyl)-ATP (TNP-ATP) bound to the Ca2+-ATPase of skeletal muscle sarcoplasmic reticulum is greatly enhanced during turnover induced by ATP plus Ca2+ (Watanabe, T., and Inesi, G. (1982) J. Biol. Chem. 257, 11510-11516). We have studied the kinetics of induction of TNP-ATP fluorescence and of its decay and have found a close correlation with levels of phosphorylated intermediate of the enzyme, E-P. Steady-state kinetic studies suggested competitive binding of ATP and TNP-ATP to the catalytic site, with Km and Ki values of 2.4 and 1.0 microM, respectively. Rate constants for fluorescence enhancement and for E-P formation in the presteady state were 1.2 s-1 or 97-130 s-1 under conditions resulting in TNP-ATP or ATP saturation respectively, of the enzyme at inception of reaction. The slow process was concluded to be the koff for dissociation of TNP-ATP from the catalytic site. Following this dissociation, a second TNP-ATP site was detected, which both formed (97-130 s-1) and decayed (0.22 s-1) synchronously with E-P. TNP-ATP binding to this noncatalytic site was rapid (5 X 10(7) M-1 s-1) and resulted in high fluorescence during steady-state turnover. Fluorescence was found to be dissociated from E-P by KCl (100 mM). KCl had little effect on E-P levels, but decreased fluorescence by 68%. These studies provide independent kinetic evidence for the existence of both catalytic and noncatalytic, or "regulatory," nucleotide-binding sites, but cannot distinguish whether the two sites exist independently or whether the catalytic site is transformed into a regulatory site on phosphorylation. The latter site, which shows relatively high selectivity for TNP-ATP over ATP, and which is simultaneously hydrophobic and freely accessible to the medium, may play a role during energy transduction. The changes occurring at this site during catalysis are conveniently monitored with TNP-ATP fluorescence.
Adenosine Triphosphate↗
Lipoprotein lipase- and phospholipase A2-catalyzed hydrolysis of phospholipid vesicles with an encapsulated fluorescent dye. Effects of apolipoproteins.
The self-quenching dye, 6-carboxyfluorescein, has been encapsulated into sonicated vesicles of egg phosphatidylcholine. Porcine pancreatic phospholipase A2 and bovine milk lipoprotein lipase catalyze the hydrolysis of the phosphatidylcholine resulting in the release of the encapsulated dye and a large increase in 6-carboxyfluorescein fluorescence. The fluorescence increase occurs in parallel with the formation of lysophosphatidylcholine and is strongly dependent on Ca2+ for phospholipase A2 catalysis and on apolipoprotein C-II for hydrolysis by lipoprotein lipase. Other apolipoproteins, including apolipoproteins C-III, C-I, and A-I, do not enhance lipoprotein lipase activity towards this substrate. We conclude that the enhancement of lipoprotein lipase activity by apolipoprotein C-II is a specific property of the activator protein due to its interaction with lipoprotein lipase or an enzyme/lipid interface and not a characteristic of lipid-binding proteins in general.
Animals↗
Three regions of a yeast tRNALeu3 gene promote RNA polymerase III transcription.
A Saccharomyces cerevisiae tRNALeu3 gene has been dissected to identify sequences essential for recognition by the yeast RNA polymerase III transcription apparatus. Three putative promoter regions have been identified, one each in the 3'- and 5'-halves of the tRNA coding sequence, the A- and B-blocks, respectively, and one in the 5'-flanking region. DNA fragments derived from the intact gene and bearing the 5'-flanking region, the 5'-flanking region plus the A-block, the A- and B-blocks without the 5'-flanking region, the 5'-flanking region with the B-block, and the B-block only have been subcloned. Plasmids carrying these fragments were used as templates in a homologous in vitro transcription assay to determine the contributions of the various sequences to the template activity of the gene. No template-dependent transcription was seen when fragments with only the 5'-flanking region or B-block were tested. A very weak template-dependent transcript was observed from clones bearing the A- and B-block regions. Transcription of the fragment bearing the 5'-flanking sequence and A-block was considerably more efficient but reduced relative to the intact gene. The clone including the 5'-flanking region and 3'-half of the gene is transcribed by the yeast extract with an efficiency approaching that of the intact gene. Partial deletions were constructed in which the highly conserved 5'-flanking pentadecanucleotide sequence was replaced by vector DNA. Replacement of the sequence between positions -12 and -2 (relative to the tRNA coding sequence) decreased transcription efficiency 10-fold even though the A- and B-blocks were left intact. We conclude that this 5'-flanking region, in conjunction with either the A- or B-block sequence is sufficient to constitute a promoter for the yeast RNA polymerase III transcription apparatus.
Base Sequence↗
Hydrolysis of a fluorescent phospholipid substrate by phospholipase A2 and lipoprotein lipase.
The fluorescent phospholipid 1-acyl-2-[6-[(7-nitro-2,1,3benzoxadiazol-4 -yl) amino]-caproyl] phosphatidylcholine (C6-NBD-PC) was used as a substrate for porcine pancreatic phospholipase A2 (PA2) and bovine milk lipoprotein lipase (LpL). Hydrolysis of C6-NBD-PC by either enzyme resulted in a greater than 50-fold fluorescence enhancement with no shift in the emission maximum at 540 nm; Ca++ was required for PA2 catalysis. Identification of the products of hydrolysis showed cleavage at the sn-1 and sn-2 positions for LpL and PA2, respectively. For PA2, but not for LpL, there was a marked enhancement of enzyme catalysis at lipid concentrations above the critical micellar concentration of the lipid. Furthermore, apolipoprotein C-II, the activator protein of LpL for long-chain fatty acyl substrates, did not enhance the rate of catalysis of the water-soluble fluorescent phospholipid for either enzyme.
Apolipoprotein C-II↗
Oxytocin and neonatal hyperbilirubinemia. Studies of bilirubin production.
We studied the effect of oxytocin induction or augmentation of labor on rates of bilirubin production in newborns at three different institutions. Bilirubin production, assessed quantitatively by the pulmonary excretion rate of carbon monoxide or qualitatively by the blood carboxyhemoglobin concentration, was not elevated when compared with appropriately matched control groups. Previous studies have implicated administration of large volumes of electrolyte-free dextrose solutions together with oxytocin as an important factor contributing to hemolysis in the infant. The mothers in our studies received minimal amounts of free water. We conclude that oxytocin induction or augmentation of labor does not result in neonatal hemolysis and subsequent hyperbilirubinemia when it is administered without large volumes of sodium-free intravenous solutions.
Bilirubin↗
Quantitation of flecainide acetate, a new antiarrhythmic agent, in biological fluids by gas chromatography with electron-capture detection.
A sensitive and selective gas chromatographic (GC) method for the quantitation of flecainide acetate, a new antiarrhythmic agent, was developed. The unchanged drug and internal standard were separated from biological fluids by a sequence of solvent extractions and then the drug was derivatized. The pentafluorobenzamide derivatives were chromatographed on a 3% SP-2250 glass column and detected with a nickel-63 electron-capture detector. By this method, greater than or equal to 12.5 ng of flecainide/mL can be quantitated in a 1-mL sample of plasma, saliva, or urine. The intraday precision, expressed as the RSD, at plasma levels of 12.5, 25, 50, 100, 200, 300, 400, and 600 ng/mL was 3.4, 6.2, 5.3, 6.4, 1.0, 1.6, 2.0, and 0.5%, respectively; the accuracy, expressed as relative error at these levels was -24.6, -6.9, -6.0, +0.6, +3.8, -0.3, +2.4, and -1.4%, respectively. The interday precision at these levels was 13.8, 13.0, 5.7, 7.6, 8.3, 6.1, 9.0, and 5.4%, respectively. Several other antiarrhythmic agents and one beta-blocker, which might be administered concurrently with flecainide acetate, do not interfere with the assay.
Anti-Arrhythmia Agents↗
Transcription of tRNA gene fragments by HeLa cell extracts.
Promoter elements for tRNA genes from several eukaryotes have been identified in the coding regions of the DNA. There are two non-contiguous sequences, an A-block or D-control region and a B-block or T-control region, located in the 5'- and 3'-halves of the tRNA sequence respectively. Both sequences are about 12 bp in length and are strongly conserved in all tRNA genes. We and others have recently shown that some tRNA genes from yeast and insects have a third control region located in the 5'-flanking sequences adjacent to tDNA. The tRNALeu3 genes from yeast have such a sequence. It is strongly conserved in non-allelic copies of tRNALeu3 genes as well as several other yeast tRNA genes. This 5'-flanking sequence is indispensable for transcription of the gene in an in vitro system derived from yeast cells. Further, the transcription apparatus from yeast will recognize and transcribe gene fragments including the 5'-flanking sequence in conjunction with either the A or B-blocks. Neither the 5'-flanking sequence alone nor the A and B-blocks lacking the 5'-flanking region can act as promoters in the yeast system. We have used these tRNALeu3 gene fragments to analyze the promoter activity of the three control regions with a Hela cell extract which actively transcribes class III genes. We find that the Hela cell system requires the presence of both A and B-block sequences and is insensitive to 5'-flanking DNA.
Base Sequence↗
Cholestyramine-enhanced fecal elimination of carbon-14 in rats after administration of ammonium [14C]perfluorooctanoate or potassium [14C]perfluorooctanesulfonate.
After a single intravenous dose of ammonium [14C]perfluorooctanoate [( 14C]PFO, 13.3 mg/kg) or of potassium [14C]perfluorooctanesulfonate [( 14C]PFOS, 3.4 mg/kg) to rats, cholestyramine fed daily as a 4% mixture in feed was shown to increase the total carbon-14 eliminated via feces and to decrease liver concentration of carbon-14. Rats were fed cholestyramine in feed for 14 days after administration of [14C]PFO and for 21 days after administration of [14C]PFOS. Control rats were administered radiolabeled fluorochemical but were not treated with cholestyramine. Cholestyramine treatment increased mean cumulative carbon-14 elimination in feces by 9.8-fold for rats administered [14C]PFO and by 9.5-fold for rats administered [14C]PFOS. After [14C]PFO, a mean of 4% of the dose of carbon-14 was in liver of cholestyramine-treated rats at 14 days versus 7.6% in control rats; after [14C]PFOS, 11.3% of the dose was in liver at 21 days versus 40.3% in control rats. After administration of either radiolabeled compound, plasma and red blood cell carbon-14 concentrations, which were relatively lower than liver concentrations, were also significantly reduced by cholestyramine treatment.
Animals↗
Noninvasive measurement of cardiac output in healthy preterm and term newborn infants.
Although values for cardiac output in the newborn infant have been reported previously, the methods utilized have been invasive. To assess if cardiac output could be determined noninvasively in the neonate, we measured mean ascending aortic blood flow velocity (VAo) in well newborns using a portable 5MHz, range gated, pulsed Doppler velocity meter. Measurements were made from a suprasternal approach in 8 preterm (mean birth weight 1718 gm; mean estimated gestation age 33.3 weeks) and 14 term (mean birthweight 3127 gm; mean EGA 39.8 weeks) healthy infants under one week of age. The internal ascending aortic systolic diameter was determined echographically and aortic cross sectional area was calculated: AAo = pi d2/4. Ascending aortic blood flow (QAo) was then computed as QAo (ml/min) = VAo (cm/sec) X AAo (cm2) X 60 (sec/min). With the exclusion of patent ductus arteriosus (PDA) and detectable intracardiac defects, QAo was taken to equal cardiac output. Flow determinations were normalized to body weight. The 8 preterm infants had a mean cardiac output of 221 +/- 56 (+/- SD) ml/min/kg. The 14 term infants had a similar mean cardiac output of 236 +/- 47 ml/min/kg. The mean cardiac output of all 22 infants was 230 +/- 50. This study establishes normal values for cardiac output determined noninvasively by the Doppler technique, in the first week of life in healthy infants. These values are similar to previously reported systemic blood flows, which were determined by cardiac catheterization and thermodilution methods in healthy newborn infants.
Aorta↗
Influence of bacterial-antibiotic interactions on subsequent antimicrobial activity of alveolar macrophages.
The efficacy of an antibiotic in the treatment of bacterial infections depends upon the interactions of drug, bacteria, and phagocytes. In an examination of certain of these interactions, overnight cultures of 3H-labeled Staphylococcus aureus were briefly incubated in the presence or absence of various antibiotics prior to phagocytosis by rabbit alveolar macrophages. Preincubation of organisms with an inhibitor of bacterial protein synthesis (clindamycin, erythromycin, chloramphenicol, or rifampin) but not with a cell wall-active drug (penicillin G or cefazolin) led to an increase in phagocytosis and early intracellular killing by alveolar macrophages. Antibiotic-mediated susceptibility of S aureus to ingestion by alveolar macrophages correlated with the inhibition of bacterial protein synthesis. Clindamycin-treated staphylococci were more efficiently opsonized by heat-inactivated serum and bound larger amounts of specific antibody than did control organisms. Thus, compromise of one or more antiphagocytic surface components secondary to decreased protein synthesis is the means by which certain antibiotics influence bacterial susceptibility to the antimicrobial mechanisms of phagocytes. This effect may be an important determinant in the success of treatment with inhibitors of bacterial protein synthesis.
Anti-Bacterial Agents↗
Neurologic manifestations of Legionnaires' disease.
The neurologic manifestations of Legionnaires' disease were reviewed in this paper. Nine (42.9%) of 21 patients seen at this institution had neurologic abnormalities during acute infection, comparable to 52% of patients found in the literature. Abnormal mentation was most common, occurring in all our patients and in 29.6% of patients in the literature. Encephalopathy disproportionate to metabolic disturbances varied from mild confusion to coma, was not associated with increased mortality, and tended to resolve with acute illness although some patients reported persistent memory defects. Rarely did these changes in mentation precede the development of pulmonary infiltrates. Headache occurred in two (22.2%) of our patients and in 28.7% of those in the literature. Headache, noted in many febrile illnesses, is common but nonspecific in Legionnaires' disease. Other neurologic abnormalities including cerebellar dysfunction and focal deficits were relatively infrequent and tended to persist beyond resolution of clinical infection. In some cases these neurologic derangements may have occurred coincidentally with Legionnaires' disease. Diagnostic evaluations and autopsies were frequently normal, nonspecific, or revealing of pathology unrelated to infection. Only two patients had evidence of direct invasion of the central nervous system by Legionella, and the cause of encephalopathy and neurologic abnormalities in most cases remains unclear. Patients with neurologic abnormalities and Legionnaires' disease deserve full evaluation to exclude other entities. Only encephalopathy appears to be a characteristic manifestation of Legionnaires' disease.
Aged↗
Comparison of methods of enumerating coliforms after UV disinfection.
In view of the differences that have been found between the most-probable-number and membrane filtration methods for the recovery of coliforms from chlorinated samples, the survival of total and fecal coliforms in UV-irradiated effluent samples, as tested by the most-probable-number and standard single-step membrane filtration methods, was compared. There were no significant differences in the survival of total and fecal coliforms, as tested by the two methods. In a separate set of experiments comparing total and fecal coliform survival, as tested by the most-probable-number method, only a very small but statistically significant difference of 0.1 log survival units was found. For UV-disinfected wastewater effluents, standard one-step membrane filtration procedures are comparable to standard most-probable-number procedures.
Disinfection↗
Protein turnover in heart and diaphragm of rat fetus.
Fractional rate constants for protein synthesis (KS) in fetal rat heart and diaphragm were determined by the constant infusion technique. Uniformly labeled [14C]tyrosine was infused at a constant rate into the maternal jugular vein of unanesthetized unrestrained pregnant rats for 6-10 h at days 19 and 21 of gestation and KS calculated from the protein-bound to tissue-free tyrosine specific radioactivity ratio and the rate constant for attainment of plateau tyrosine specific radioactivity in fetal plasma (lambda p). Rate constants for protein degradation (KD) were calculated by subtracting fractional growth rate (KG) from KS. In both tissues, protein accretion during the most rapid phase of growth (day 19) was accomplished by greater rates of synthesis and lower rates of degradation when compared with a time of lesser growth (day 21).
Animals↗
Neonatal lung neutrophils and elastase/proteinase inhibitor imbalance.
Serial bronchoalveolar lavage (BAL) was performed prospectively on 10 normal control subjects, 20 Respiratory Distress Syndrome (RDS), and 11 Bronchopulmonary Dysplasia (BPD) newborn infants to evaluate the role of pulmonary inflammation in neonatal lung disease. Minimal inflammation was found in BAL at less than 24 h of life in all groups, but significant pulmonary polymorphonuclear leukocyte (PMN) influxes were noted at 96 h in RDS and BPD compared with control subjects. By 1 wk of life, BAL PMN counts returned to normal in RDS, but counts remained significantly elevated through 5 wk in BPD. Alveolar macrophage (AM) counts were significantly elevated at 96 h in RDS (p less than 0.05), but were significantly depressed in BPD at 4 and 5 wk (p less than 0.05). The BAL elastase/alpha 1-proteinase inhibitor (alpha 1Pi) ratios in RDS did not differ from those of normal control subjects; however, these ratios were significantly elevated from 1 through 4 wk of life in BPD, placing these infants at risk for proteolytic lung damage. Lavage elastase levels were elevated in both RDS and BPD, associated with a parallel increase in BAL alpha 1Pi in RDS and depressed BAL alpha 1Pi in BPD. These findings suggest that pulmonary inflammation, associated with a prolonged PMN influx and an imbalance between elastase and alpha 1Pi, may contribute to the development of the neonatal chronic lung disease, BPD.
Albumins↗
Bilirubin binding in the plasma of newborns: critical evaluation of a fluorescence quenching method and comparison to the peroxidase method.
Bilirubin binding affinities and capacities and apparent unbound ("free") bilirubin levels were determined in serum samples from 47 high-risk newborns, in 22 samples of cord serum, and in serum samples from 15 Greek children with marked hyperbilirubinemia, by both fluorescence quenching and peroxidase methods. The free fatty acid:albumin molar ratio was also determined for serum samples from high-risk newborns. In vitro and in vivo measurements suggest that free fatty acids are rarely present at levels that produce significant displacement of bilirubin, which is in agreement with previous studies. The two bilirubin binding assays showed only fair correlation with sizable discrepancies for many specimens. Technical difficulties inherent in the fluorescence quenching method and possible sources of error are discussed. Our observations suggest that routine application of these two assays as the primary criterion for therapeutic intervention (e.g., exchange transfusion) is premature.
Bilirubin↗