Biomedical subjects
Publications and source records attributed to L M Field.
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BACKGROUND: A variety of approaches have been described for the removal of lip lesions, but approaches to submucosal lesions are not generally explored as a separate category of problem. A new adaptation of hinged tissue elevation occurred when vermilion mucosa was elevated, a small mucous membrane flap created, and then reapplied over a submucosal lip mass defect. OBJECTIVE: Presentation of a new application of hinged flaps, using lip mucosa as the flap tissue to be raised and reapplied to the underlying muscularis. The purpose of the technique was to preserve all tissue above the mass, while successfully removing the submucosal lesion. RESULTS: Application of the hinged mucosal flap concept to the lower lip resulted in complete preservation of the lip contour without invasion of the infravermilion shelf or subjacent chin areas, and without any anterior vermilion invasion. METHOD: The surgical technique of evolving a hinged mucosal lip flap is described, with multiple photographs demonstrating the serial maneuvers carried out. Surgical intervention resulted in complete obliteration of the benign lesion with essentially no visible scarring and no change in lip contour. CONCLUSION: Utilization of a hinged mucosal flap on the lip for removal of smaller submucosal lesions results in complete preservation of the delicate lip contours without sacrifice of subjacent lip tissue or visible scar beyond the vermilion junction. Further extension of the hinged flap principle to subepidermal exploration and extirpation elsewhere logically follows. Applying the principles of hinged flaps to lip submucosal lesions results in virtually undetectable surgical sequellae.
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Biochemical and molecular studies have established that in the peach-potato aphid, Myzus persicae, insecticide resistance is conferred by amplification of genes encoding the insecticide-detoxifying esterases E4 or FE4. Here we report that two insecticide-resistant clones of the closely related tobacco aphid Myzus nicotianae have elevated esterases indistinguishable from E4 and FE4 and amplified esterase DNA sequences, and flanking regions, with identical restriction maps to the M. persicae genes. Furthermore, the DNA sequences of c. 630 bp fragments of the E4 and FE4 genes of M. persicae are different from each other but identical to the fragment from corresponding M. nicotianae clones. The existence of apparently identical insecticide resistance genes in the two species can be best explained by the selection of the amplified genes in M. persicae, transfer to hybrids of M. persicae and M. nicotianae by sexual reproduction and subsequent spread through M. nicotianae populations.
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An increased use of multiple flaps applied to single reconstructive problems is encouraged. Removal of a basal cell carcinoma involving the medial canthus and adjacent lateral nasal root skin resulted in significant defect. When a glabellar "fan" flap failed to provide adequate tissue for canthal reconstruction without undue distortion, a preplanned medial cheek rotation flap followed sequentially in the repair process. The basic principles of an O-to-Z flap reconstruction were therefore fulfilled by conjoining two different flap design applications.
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The effects of high concentrations of inspired oxygen on cerebrovascular haemodynamics were studied in healthy human volunteers using transcranial Doppler measurements of middle cerebral artery blood velocity. If the end-tidal carbon dioxide level was kept constant, the measured blood velocity and the calculated Pulsatility Index showed no significant change when subjects were breathing 21, 40, 75 or 100% oxygen.
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Full-length cDNA clones encoding the esterases (E4 and FE4) that confer insecticide resistance in the peach-potato aphid [Myzus persicae (Sulzer)] were isolated and characterized. The E4 cDNA contained an open reading frame of 1656 nucleotides, coding for a protein of 552 amino acids. The FE4 cDNA shared 99% identity with E4 over this region, the most important difference being a single nucleotide substitution resulting in the FE4 mRNA having an extra 36 nucleotides at the 3' end. The derived amino acid sequences for the N-terminus of E4 and FE4 were identical, with the first 23 residues being characteristic of a signal peptide and the next 40 residues being an exact match to the N-terminal sequence determined by Edman degradation of both purified proteins. The predicted molecular masses of 58.8 and 60.2 kDa for the E4 and FE4 polypeptides were consistent with those previously observed by in vitro translation of mRNA. Five potential N-linked glycosylation sites were present in both polypeptides, in accordance with earlier evidence that the native esterases are glycoproteins. Comparison of the aphid esterase protein sequences with other serine hydrolases provided evidence that their activity involves a charge-relay system with a catalytic triad the same as that found in acetylcholinesterase. Restriction mapping and sequencing of cloned genomic DNA showed that the E4 gene is spread over 4.3 kb with six introns and that the previously reported differences between the 3' ends of the E4 and FE4 genes result from single nucleotide substitutions and not gross differences in the DNA sequences.
We have studied the effect of nitrous oxide on cerebral haemodynamics in 24 healthy male volunteers. Hemispherical cerebral blood flow (CBF) was measured using the xenon-133 inhalation technique, blood flow velocities in the right middle cerebral artery were calculated using transcranial Doppler ultrasound and the pulsatility index (PI)--the inverse of which is theoretically proportional to flow in the vessel under investigation--was derived from analysis of the spectrally analysed velocity pulse wave form obtained from the middle cerebral artery. Each variable was measured with the subject inhaling 100% oxygen (1st baseline), 30% nitrous oxide in oxygen, 100% oxygen (2nd baseline) and 60% nitrous oxide in oxygen. CBF was significantly greater with 30% (0.01 > P > 0.001) and 60% nitrous oxide (P < 0.001) compared with baseline, although the difference between 30% and 60% nitrous oxide was not significant. Changes in 1/PI correlated closely with those in hemispherical CBF. Blood flow velocities increased significantly with 30% (P < 0.001) and 60% nitrous oxide (0.005 > P > 0.001), the difference between 30% and 60% nitrous oxide also being significant (0.005 > P > 0.001). We observed a plateau in the change in CBF caused by nitrous oxide and suggest that this may be explained by activation of intact autoregulative mechanisms in healthy human brain.
We describe the successful management of general anaesthesia for Caesarean section in a patient with poorly controlled paroxysmal ventricular tachycardia of pregnancy. The use of alfentanil before laryngoscopy and tracheal extubation ensured cardiostability without compromising maternal or fetal wellbeing. General anaesthesia allows prompt cardioversion. We believe that in the presence of a life-threatening unstable cardiac rhythm this consideration outweighs any theoretical advantage of regional blockade.
BACKGROUND: A postoperative nasal root and glabellar forehead deformity comprised both vertical and horizontal elements, with scar contracture and fixation across the left medial nose base, extending into the adjacent superior canthal region. METHODS: A two-stage reconstruction was performed, initially correcting the vertical centrally placed forehead depression by dual subcutaneous flaps advanced centrally and joined. The horizontal nasal root contracture was repaired at a second stage utilizing a procerus muscle transposition flap elevated on the ipsilateral deep contracture side, imbricated in serpentine fashion on itself and sutured into the depression over the scar base. RESULT: Significant improvement followed. CONCLUSION: The careful and precise placement of subcutaneous tissue and muscle can serve to assist in filling certain deep defects and in elevating scar lines.
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