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Biomedical subjects

D L Baldwin

Publications and source records attributed to D L Baldwin.

At least 19 recordsLinked to original sources
PubMed2002

Long-term follow-up of endoscopic stapled diverticulotomy.

We report a consecutive series of 31 patients who underwent endoscopic stapled diverticulotomy. The patients' notes were reviewed retrospectively to gather data on their original admission and a postal survey was conducted to establish patient satisfaction, their ability to swallow and re-operation data. Three patients were lost to follow-up. Nine of the remaining 28 died at a median of 18 months. The remaining 21 were followed up for a median of 59 months. The data showed that, at 5 years, 94.4% of patients had an improvement in their swallowing, and 50% had an entirely normal swallow. In order to achieve this result, 19% of patients required a second procedure, and one patient (3.2%) required a third (open) procedure. Endoscopic stapled diverticulotomy has well-established, short-term advantages. This series shows that it has a good long-term outcome that is similar to established open techniques and probably better than other techniques of endoscopic diverticulotomy, i.e. diathermy or laser.

Aged↗
PubMed1999

Complete fusion of the vocal cords; an unusual case.

A case is presented of a woman who sustained a 35% body surface area mixed depth cutaneous burn, together with a significant inhalational injury. The patient required emergency resuscitation with endotracheal intubation and subsequently tracheostomy. This resulted in an unfortunate complication of a total adhesion between the vocal cords which extended into the subglottic area, causing complete occlusion of the airway.

Adult↗
PubMed1999

Meningiomas involving the internal auditory canal: a diagnostic and surgical challenge.

Meningiomas are the second most common lesion encountered within the cerebello-pontine angle (CPA) and rarely project into or originate from the internal auditory meatus (IAM). It is important to distinguish between meningiomas and acoustic neuromas preoperatively as the choice of surgical approach may differ depending on the tumour type. Fortunately, most lesions can be accurately diagnosed with gadolinium-enhanced magnetic resonunce imaging (MRI). We report six cases of meningioma involving the IAM, often leading to an incorrect preoperative MRI diagnosis. We highlight the challenges these tumors present to radiologists and surgeons.

Journal Article↗
PubMed1998

Endoscopic stapled diverticulotomy: a real advance in the treatment of hypopharyngeal diverticulum.

Between November 1993 and May 1996, 51 patients with a hypopharyngeal diverticulum were treated by endoscopic stapled diverticulotomy. Normal swallowing was resumed within 36 h of surgery in 73%, and in 93% by 72 h. Two patients required nasogastric feeding for 5-7 days. There were no operative deaths or serious operative morbidity, and there have been no recorded cases of clinical recurrence of pouches to date (maximum follow-up 562 days: 46 cases over 12 months). The low morbidity, short hospital stay and early return to normal feeding, combined with a relative absence of complications or pouch recurrence, make endoscopic stapled diverticulotomy the treatment of choice for the majority of patients.

Aged↗
PubMed1996

Intra-operative image guidance in otolaryngology--the use of the ISG viewing wand.

The ISG viewing wand is an intra-operative guidance system with a proprioceptive robotic-like jointed arm. It provides surgeons with almost instantaneously reconstructed computer-generated CT or MRI images in two or three dimensions and can correlate any point within the operative field to its corresponding locus on the reformatted scan images. In addition to having been used in over 400 neurosurgical patients in Bristol, 14 patients with skull-base, cerebello-pontine angle or temporal bone lesions have also undergone wand-guided resections. The wand has proved to be particularly useful in pre-operative planning, allowing minimally-invasive incisions, providing per-operative navigation, identifying the relationship and proximity of important anatomical structures and in assessing the extent of lesion resection. We illustrate the advantages of intra-operative image-guidance by discussing four cases. The potential applications of this form of imaging technology to other otolaryngological procedures are discussed.

Adult↗
PubMed1995

Supraglottic transection: results of repair and functional outcome.

We present two cases of supraglottic transection, with concomitant neurotemesis of the superior laryngeal nerve. Both cases were repaired primarily and a temporary tracheostomy was used to protect the airway. In both cases subsequent decannulation was achieved within four weeks, following the initial injury. No long-term swallowing or voice disturbance was noted in either case. We recommend that in such cases it is unnecessary to repair the nerves directly, but that careful repair of the wound itself will achieve a functional result.

Adult↗
PubMed1994

Day-case adenoidectomy, parental opinions and concerns.

Day-case surgery has been urged on the National Health Service by the Audit Commission in the last decade despite concerns about safety. A questionnaire was posted to the parents of 109 children who had recently undergone day-case adenoidectomy, addressing parental concerns and opinions. Eighty per cent of the questionnaires were returned. A high level of satisfaction with day-case adenoidectomy was expressed by the parents. All the children were observed for six hours after surgery prior to discharge. One child was visited at home by his general practitioner in the first 24 hours of discharge but there were no serious post-operative complications and none of the children required re-admission to hospital. Day-case adenoidectomy is safe, very acceptable to parents and does not result in a greatly increased workload for general practitioners.

Adenoidectomy↗
PubMed1992

Cochlear blood flow and microvascular resistance changes in response to hypertonic glycerol, urea, and mannitol infusions.

The effect of hyperosmotic agents on cochlear blood flow (CBF) was tested in normal guinea pigs and in guinea pigs having prior unilateral operations to ablate the endolymphatic duct. Laser-Doppler-measured CBF was normalized to remove apparent changes related directly to systemic blood pressure. Hyperosmotic fluids were given via venous infusion: glycerol (20% and 40% solutions), urea (10%, 30%, and 40% solutions), and mannitol (40% solution). All agents were dissolved in 0.9% saline and the mixtures were given at a rate of 0.3 to 0.6 mL/min for 5 minutes. Control infusions were of 0.9% saline and isotonic dextran 70 (Pharmacia). All hyperosmotic infusions resulted in similar increases in normalized cochlear blood flow (nCBF) that extended to a maximum of 300% of the baseline value in a dose-dependent way during the infusion time period. Within approximately 30 minutes following infusions, nCBF had returned to baseline levels. Saline infusion alone had little effect on nCBF, but isotonic dextran 70 gave a sustained increase to 122% of the baseline levels. There was no difference between the responses of nCBF in hydropic and normal cochleas for either control or hyperosmotic solutions. Measurements of systemic hematocrit at time intervals during and following the infusions showed that transient reductions of up to approximately 8% (for the maximum osmotic challenge) occurred during the infusion. It is concluded that the hyperosmotic treatments tested here are equally effective for short-term enhancements of nCBF in both normal and hydropic cochleas. The basis of the flow increase is partially rheologic and partially due to a local vasodilation.

Animals↗
PubMed1991

Influence of topically applied adrenergic agents on cochlear blood flow.

This study was designed to assess the role of adrenergic receptors in the control of cochlear blood flow. Laser Doppler flowmetry was used to determine the effects of adrenergic drugs topically applied to the round window membrane of the cochlea. The relative influence of the various receptor types (alpha 1, alpha 2, beta 1, and beta 2) was examined by a selection of agonists and antagonists. The agonists norepinephrine and epinephrine, which have mixed alpha- and beta-receptor effects, and phenylephrine, a strong alpha 1-agonist, all induced a dose-dependent reduction in cochlear blood flow. The agonists isoproterenol (beta-active), salbutamol (alpha 2-active) had no effect on cochlear blood flow. Of the antagonists, when tested alone, only the selective alpha 1-antagonist prazosin had a direct effect on cochlear blood flow, demonstrating an increase in cochlear blood flow. The selective alpha 2-antagonist idazoxan, the beta-antagonist propranolol, and the unselective alpha-antagonist phentolamine had no effect on cochlear blood flow. Interaction studies of agonists and antagonists were performed to specifically define the receptor subclasses responsible for the cochlear blood flow increases with norepinephrine and epinephrine. The results are consistent with the presence of an alpha 1-adrenergic sympathetic control of cochlear blood flow.

Administration, Topical↗
PubMed1990

Hearing conservation in acoustic neuroma surgery via the posterior fossa.

An increasing number of patients with an acoustic neuroma present with useful hearing in the tumour ear. Surgical removal of these tumours via the posterior fossa route may enable preservation of the cochlear nerve and otic capsule without increasing the morbidity to the facial nerve. The results of treating 51 cases of acoustic neuroma via the posterior fossa is presented. Forty four tumours measured less than 20 mm in diameter in the cerebellopontine angle and surgery was undertaken with hearing preservation as a principle objective. In 26 cases, the cochlear nerve was preserved anatomically and post-operative hearing at levels better than mean pure tone threshold of 50 dB or 50 per cent speech discrimination was recorded in 14 patients. The preservation of hearing represents a worthwhile surgical goal in selected patients with an acoustic neuroma without increasing the operative morbidity.

Cochlear Nerve↗
PubMed1988

Immune status in patients with Menière's disease.

Sera of 164 patients with classical Meniere's disease were screened for autoantibodies, immune complexes and HLA status. Increased thyroid microsomal antibodies were significant in those patients in the 40- to 60-year age range. Raised IgM complexes and C1q component of complement were significant in all age groups. Low levels of IgA complexes were a consistent finding and were significantly lower in the HLA Cw7 group. Patients with migraine had no increased incidence of immune disturbances.

Adolescent↗
PubMed1987

The effect of nedocromil sodium on nasal provocation with allergen.

We have investigated the effect of nedocromil sodium in preventing the symptoms of rhinitis occurring immediately after allergen provocation in 10 patients with allergic rhinitis. The study had a double-blind, placebo-controlled, crossover design. Nedocromil sodium (1% w/v) and placebo were administered intranasally from identical metered-dose inhalers 20 minutes before allergen provocation. Three variables were measured: nasal airway resistance, the production of secretion, and the number of sneezes. Nedocromil sodium was significantly more effective than placebo in preventing nasal obstruction (p less than 0.01), rhinorrhea (p less than 0.01), and sneezing (p less than 0.05), suggesting that this drug may be useful in the treatment of allergic rhinitis.

Adult↗
PubMed1986

Direct in vivo evidence for mast cell degranulation during allergen-induced reactions in man.

There is little or no direct in vivo evidence in man to support the involvement of mast cell-mediator release in the pathogenesis of immediate allergic reactions. We have performed a within-subject controlled study to determine the changes that occur in nasal mast cells during allergen-induced rhinitis. Twelve subjects with asymptomatic rhinitis were studied. Nasal biopsy specimens were obtained from each subject after a control solution (isotonic saline, 0.9% w/v) had been nebulized into one nostril and allergen solution (freeze-dried allergen extract reconstituted with isotonic saline) into the other. The tissues obtained were fixed in Carnoy's solution and stained with the alpha-naphthol AS-D chloroacetate esterase reaction (N AS-D CA ER). Mast cells were counted under light microscopy in the epithelium and lamina propria, and the integrity of each cell was assessed. No significant differences were found in the number of epithelial or lamina propria mast cells in biopsy specimens obtained after saline or allergen administration. However, the number of degranulated mast cells after allergen provocation (89%) was significantly greater than after instillation of control solution (15%) (p = 0.003). Changes of mast cell degranulation after allergen provocation were confirmed by electron microscopy. In six nonatopic, control subjects without rhinitis, there was no significant difference between the percentages of degranulated mast cells after allergen provocation (25.8%) and instillation of saline (24.3%). This study provides direct in vivo evidence for allergen-induced mast cell activation in man.

Adult↗
PubMed1985

Primary structure of phage mu transposase: homology to mu repressor.

The phage Mu transposase is essential for integration, replication-transposition, and excision of Mu DNA. We present the complete nucleotide and derived amino acid sequence of the transposase and analyze implications for transposase/DNA interaction. The NH2 terminus of the Mu transposase has considerable sequence homology with the Mu repressor and with the NH2 terminus of the transposase of the Mu-like phage D108. These three proteins are known to share binding sites on DNA. The protein sequence and predicted secondary structural similarities at the NH2 termini of the three proteins suggest a common DNA-binding region similar to the regions found in proteins of known structure. An internal sequence in the Mu A protein also shares these features. We anticipate that these regions will be involved in DNA recognition during transposition.

Amino Acid Sequence↗
PubMed1984

The nucleotide sequence of the B gene of bacteriophage Mu.

Bacteriophage Mu is a highly efficient transposon which requires the products of the Mu A and B genes in order to transpose at a normal frequency. We have determined the nucleotide sequence of the B gene as well as that of the A-B intergenic region upstream of B. The protein product of the gene contains 312 amino acids and has a predicted molecular weight of 35,061. As expected, there do not appear to be any potential promoter sequences in the intergenic region prior to the gene, but it is preceded by a strong Shine-Dalgarno sequence. The intergenic region does not contain any obvious transcription termination sequences. The frequency of optimal codon usage is similar to that for other transposon and phage genes, and the amino acid composition is comparable to that of an "average" E. coli protein. A region near the amino terminus of the protein resembles the highly conserved bihelical fold which is involved in DNA contact and sequence specific recognition in a number of DNA binding proteins.

Amino Acid Sequence↗
PubMed1984

Tracheostomy 'decannulation panic' in children: fact or fiction?

The phenomenon of tracheostomy 'decannulation panic' is likely to occur in children but probably is not psychologically based. The relatively small airway, local reflexes and changes in airway resistance seem sufficient to explain it on a mechanical basis. Because there were delays and failures in this series despite an apparently adequate airway, it is recommended that decannulation be performed on a controlled and gradual basis. The method of blocking a fenestrated tracheostomy tube provides a margin of safety. Chest physiotherapy, humidification and mucolytic agents will assist in preventing the acquisition of chest infection. Prophylactic antibiotics and steroids, however, do not appear to be of value and may actually be harmful.

Adolescent↗