The child with a tracheotomy. A review of the surgical options in airway reconstruction.
Explore the source record for details and available documents.
Child, Preschool↗
Biomedical subjects
A F Drake
Publications and source records attributed to A F Drake.
Cationization of bovine serum albumin alters its conformation as well as its charge.
The molecular charge on bovine serum albumin (BSA) was modified by substituting carboxyl groups on the protein with ethylenediamine, thereby producing a highly cationic derivative with a pI of 9.3 to 9.5. Gel-filtration studies showed that the molecular weight of BSA was not significantly altered after cationization. When the cationized BSA was administered to rabbits using a chronic serum sickness schedule of injections, the animals developed a membranous glomerulopathy similar to the human disease, except that approximately one-third of the animals also showed focal and segmental endocapillary proliferation. Comparison of the circular dichroism spectra of native and cationized BSA showed that the substitution of the carboxyl groups resulted in a 50% reduction in the alpha-helical content of the native molecule. This conformational change should be considered as a possible determinant of the different immune response and immunopathology associated with the cationized molecule compared with native BSA.
Animals↗
Protein conformation changes as the result of binding to reversed-phase chromatography column materials.
The conformational changes of the protein alpha-chymotrypsinogen which may take place on reversed-phase chromatographic material of differing hydrocarbon chain lengths e.g. C4, C6, C8, C10 and phenyl, have been studied by circular dichroism as a function of 1-propanol concentration and pH of the solvent before and after binding to the reversed-phase material.
Animals↗
Conformational studies of a synthetic peptide corresponding to the repeat motif of C hordein.
C hordein, a storage protein from barley grains, has an Mr of about 53,000, and consists predominantly of repeated octapeptides with a consensus sequence of Pro-Gln-Gln-Pro-Phe-Pro-Gln-Gln. Previously reported hydrodynamic and c.d. studies indicate the presence of beta-turns, the repetitive nature of which may lead to the formation of a loose spiral. In order to study these turns we have compared the structures of a synthetic peptide corresponding to the consensus repeat motif and total C hordein by using c.d. and Fourier-transform i.r. spectroscopy. The synthetic peptide exhibited spectra typical of beta I/III reverse turns when dissolved in trifluoroethanol at 22 degrees C and in water at 70 degrees C, but 'random-coil'-like spectra in water at 22 degrees C. The whole protein also showed increases in beta I/III reverse turns when dissolved in increasing concentrations of trifluoroethanol (50-100%, v/v) or heated in ethanol/water (7:3, v/v). Two cryogenic solvent systems were used to determine the c.d. spectra of the peptide and protein at temperatures down to -100 degrees C. Methanol/glycerol (9:1, v/v) and ethanediol/water (2:1, v/v) were selected as analogues of trifluoroethanol/water and water respectively. The peptide exhibited beta I/III-reverse-turn and 'random-coil'-like spectra in methanol/glycerol and ethanediol/water respectively at 22 degrees C, but a spectrum similar to that of a poly-L-proline II helix in both solvents at -100 degrees C. Similarly the proportion of this spectral type also increased when the whole protein was cooled in both solvents. These results indicate that a poly-L-proline II conformation at low temperatures is in equilibrium with a beta I/III-turn-rich conformation at higher temperatures. The latter conformation is also favoured in solvents of low dielectric constant such as trifluoroethanol. The 'random-coil'-like spectra exhibited by the protein and peptide in high-dielectric-constant solvents at room temperature may result from a mixture of the two conformations rather than from the random-coil state.
Circular Dichroism↗
Ultraviolet and magnetic-circular-dichroic spectroscopic studies of Gd(III) complexed with diethylenetriaminepentaacetic acid. A contrast agent for NMR imaging.
Sensitive probes are required for studying the biochemistry of Gd(III) contrast agents used in magnetic resonance imaging. We show that complexation of Gd(III) by diethylenetriamine-N,N,N',N',N"-pentaacetic acid (DTPA) in aqueous solution can be readily determined from the sharp 4f-4f bands for free and bound Gd(III) in the range 270-282 nm, and, with greater sensitivity, from the associated magnetic-circular-dichroic spectra.
Circular Dichroism↗
Effects of oxidative stress on some physiochemical properties of caeruloplasmin.
We report the effects of oxidative stress generated by low-intensity u.v. irradiation (366 and 254 nm), dialysis against ascorbate and isolated stimulated neutrophils on some physicochemical properties of caeruloplasmin. Low-intensity u.v. irradiation resulted in a loss of ferroxidase activity and 610 nm absorption, changes previously reported to occur during storage and manipulation of caeruloplasmin. These alterations were found to correspond to aggregation of the protein, induction of visible fluorescence (excitation, 360 nm; emission, 454 nm), changes in c.d. spectra which were indicative of alterations in protein conformation, loss of half-cystine, tryptophan and tyrosine content and loss immunoreactivity. The changes in the far-u.v. c.d. spectrum of caeruloplasmin were more pronounced than those observed for u.v.-irradiated IgG. Similar c.d. changes and induction of fluorescence were observed following dialysis of caeruloplasmin against ascorbate or exposure to stimulated neutrophils. It is concluded that the lability of caeruloplasmin may arise from oxidative modification, in addition to the previously described susceptibility of this protein to proteolysis.
Amino Acids↗
Isolation and characterization of the diastereoisomers of a series of phosphate-ethylated dinucleoside monophosphates.
Internucleotide phosphate esterification is a common reaction of many potent carcinogenic alkylating agents. It can give rise to two stereochemically distinct molecules about a triesterified phosphorus atom. The eight individual diastereoisomers derived from phosphate ethylation of d-ApT, d-CpT, d-GpT, and d-TpT were prepared from o-chlorophenyl phosphotriester intermediates and isolated by reverse-phase HPLC. Each pair of isomers, together with its parent analog, was examined by variable temperature circular dichroism. The results are interpreted in terms of secondary structure changes from which the absolute configurations of the ethylated phosphate groups can be inferred. These configurational assignments were confirmed by 31P NMR.
Chromatography, High Pressure Liquid↗
Spectroscopic studies on IgG aggregate formation.
Spectroscopic techniques have been used to examine the effects of IgG of heating, irradiation by ultraviolet light and exposure to glutaraldehyde. Relatively few changes were observed in treated IgG which remained unaggregated but several significant size-dependent changes were observed in aggregated IgG. These results suggest that IgG aggregate formation by cross-linking with glutaraldehyde involves the least perturbation of the basis IgG structure, whereas aggregate formation by heating involves the most, with ultraviolet irradiation occupying an intermediate position.
Glutaral↗
Why do all lariat RNA introns have adenosine as the branch-point nucleotide? Conformational study of naturally-occurring branched trinucleotides and its eleven analogues by 1H-, 31P-NMR and CD spectroscopy.
1H-NMR conformational studies of six branched triribonucleotides where the branch-point nucleotide was either U, C or G (4-9) have been carried out by assigning 1H resonances through 2D NMR and then observing the temperature-dependent (i) chemical shifts of the aromatic and the anomeric protons, and (ii) shifts of the equilibrium of N and S pseudorotamer populations of each sugar moiety. The data have been compared with those of 2'----5' dimers (1-3) and other branched trimers (10-16). It emerged that all the branched trimers (4-16) adopt a conformational state closer to the corresponding 2'----5' dimers than the corresponding 3'----5' dimers. A temperature-dependent 31P chemical shift study confirmed that the conformational constraint is mainly associated with the 2'----5' phosphate linkage. Although, it appeared with the CD data that when C or especially when U is at the branch-point the overall constraint is weak. This suggests that even if these trimers adopt a 2'----5' dimer geometry, there is a lack of stabilization by strong stackings within the molecule. This is in sharp contrast with the results found for A (10-16) and to a smaller extent for G (8, 9) at the branch-point.
Adenosine↗
Lateral cricoid cuts as an adjunctive measure to enlarge the stenotic subglottic airway: an anatomic study.
The technique of laryngotracheoplasty, with an anterior approach, with or without a posterior cut, and with or without anterior or posterior cartilage grafts, has been described previously. On occasion, a severely stenotic subglottis or aberrant shape to the cricoid cartilage makes division of the lateral aspects of the cricoid cartilage desirable. In attempting to delineate the relationship of the recurrent laryngeal nerve to proposed lateral cricoid cuts, an anatomic study was conducted. Dissections of neonatal, infant, child and adult larynges and trachea were carried out, with the relative distance of a cut through the lateral cricoid cartilage to the recurrent laryngeal nerve measured and outlined. The distance was very close in the fetal larynx (measuring 1.5 mm in the 23rd week of gestational age), with an increase in dimension in the infant and child, increasing to a distance of over 1 cm in the mature adult. The clinical significance of this relationship to proposed cuts of the lateral cricoid in different age groups is discussed.
Adolescent↗
Perilymphatic fistulas in children: rationale for therapy.
We report 26 consecutive patients (32 ears) who were identified in a 2 year period (July 1, 1985-June 30, 1987) with unexplained sudden, fluctuating, or progressive sensorineural hearing loss (SNHL). All patients underwent an exploratory tympanotomy and a perilymphatic fistula was identified in 13 patients (14 ears). The mean change of 14 +/- 27 dB in speech reception threshold before and after surgery was significant at p = 0.08 among children with fistula and ranged from -30 to 80 dB. In children with sudden, progressive or fluctuating SNHL and multiple sensory deficits, including blindness or contralateral SNHL, or prior head trauma, prompt surgical exploration is mandatory. Additionally, the aggressive management of otitis media with effusion is essential in such patients to minimize fluctuations in hearing caused by superimposed conductive hearing loss. Caution must be exercised to separate fluctuating hearing loss from fluctuations in audiologic testing.
Adolescent↗
Ricin B chain-containing immunotoxins prepared with heat-denatured B chain lacking galactose-binding ability potentiate the cytotoxicity of a cell-reactive ricin A chain immunotoxin.
Ricin B chain incubated at 37 degrees C in the absence of lactose loses its ability to bind the galactose-containing protein, asialofetuin. Circular dichroism analysis of the B chain during thermal denaturation indicates that the loss of galactose-binding ability by the B chain correlates with limited unfolding of the molecule. As a result of this conformational change, disulfide bonds that are shielded from the solvent by the compact folded structure of the B chain become exposed and the chitobiosyl cores of both N-linked oligomannose chains become susceptible to cleavage by endoglycosidases. The heat-denatured B chain does not enhance the toxicity of a ricin A chain-containing rabbit anti-human immunoglobulin (RAHIg-A) to Daudi cells. However, when heat-denatured B chain is coupled to goat anti-rabbit immunoglobulin (GARIg), the resulting immunotoxin, GARIg-hdB, potentiates the killing of RAHIg-A-treated Daudi cells to an extent similar to that of an immunotoxin prepared with GARIg and native B chain. These results indicate that the native, galactose-binding structure of the B chain is not necessary to enhance the cytotoxicity of the cell-reactive A chain immunotoxin (IT-A) and suggests that regions of the B chain exposed by unfolding the molecule may mediate potentiation of cytotoxicity.
Adjuvants, Immunologic↗
The anterior cricoid split. Clinical experience with extended indications.
A recommended approach to postextubation infant subglottic stenosis secondary to subglottic edema employs the recently described anterior cricoid split (ACS) procedure. This technique provides an expanded subglottic airway with minimal paratracheal dissection and does not require concomitant tracheotomy. We applied this procedure in managing extubation difficulty in pediatric as well as neonatal patients. Five of ten patients in our series did not fulfill the traditional criteria for ACS. Relief of stridor and avoidance of tracheotomy were accomplished in nine of ten patients. One patient in whom mechanical ventilation was reinstituted developed an interesting complication. In properly selected infants with subglottic airway compromise, the ACS appears to be an effective adjunct in facilitating extubation.
Child, Preschool↗
An analysis of the 225-230-nm CD band of elapid toxins.
Explore the source record for details and available documents.
Animals↗
Role of oxidative modification in the lability of ceruloplasmin.
Explore the source record for details and available documents.
Ceruloplasmin↗
Reassessment of the electronic circular dichroism criteria for random coil conformations of poly(L-lysine) and the implications for protein folding and denaturation studies.
The circular dichroism (CD) spectra of poly(L-lysine) in water and ethanediol/water (2:1) solutions in the temperature range -110 to 85 degrees C are presented. The results combined with vibrational CD data are interpreted in terms of a two-state conformational equilibrium with a left-handed trans polyproline II conformation being preferred at low temperatures. The relevance of these studies to the CD criteria for random-coil conformations, the study of helix-coil transitions and protein/peptide folding is pointed out.
Circular Dichroism↗
Circular dichroism of isolated ricin A- and B-chains.
An analysis of the circular dichroism (CD) spectra of isolated ricin A- and B-chains revealed several bands not apparent in the spectrum of intact ricin. Arithmetic combination of the A- and B-chain spectra gave a composite spectrum resembling that of native ricin, indicating that the two chains did not undergo any major conformational change upon dissociation. The addition of lactose to the B-chain at pH 7.2 caused a slight perturbation of a tryptophan-derived negative CD band centred at 283 nm without change to the overall structure of the polypeptide.
Circular Dichroism↗
Alveolar soft part sarcoma of the nasal cavity: report of a case and a review of the literature.
A case of alveolar soft part sarcoma of the nasal cavity is presented. Alveolar soft part sarcoma is a rare malignant neoplasm, which often affects females (ratio 2 to 1) in their second decade. It occurs most frequently in the extremities, with an unusual predilection to involve the right side of the body. Excluding the orbit, only a few cases have been reported in the head and neck area. We present the first reported case of alveolar soft part sarcoma limited to the nasal chamber.
Adolescent↗