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Biomedical subjects

P S White

Publications and source records attributed to P S White.

At least 19 recordsLinked to original sources
PubMed2007

Endoscopic control of the sphenopalatine artery for epistaxis: long-term results.

The aim of this study was to prospectively evaluate post-operative cessation of bleeding and late recurrence of epistaxis in a cohort of patients treated by endoscopic ligation of the sphenopalatine artery. Participants comprised patients undergoing sphenopalatine artery ligation for posterior epistaxis at three east Scotland hospitals. Main outcome measures were recurrence of epistaxis in the immediate post-operative period and at long-term follow up (minimum nine months). Forty-three patients (30 men and 13 women) underwent 45 procedures; two patients underwent bilateral ligation. Two patients suffered recurrence as in-patients. Two patients experienced subsequent epistaxis requiring medical treatment. Two further patients suffered minor late epistaxis not requiring treatment. Success in preventing significant recurrence was 93 per cent. All recurrences requiring intervention occurred within one month of surgery. None of the patients in this series reported nasal complications. We found sphenopalatine artery ligation to be an effective means of achieving long-term control of posterior epistaxis.

Adult↗
PubMed2004

A combined linkage-physical map of the human genome.

We have constructed de novo a high-resolution genetic map that includes the largest set, to our knowledge, of polymorphic markers (N=14,759) for which genotype data are publicly available; that combines genotype data from both the Centre d'Etude du Polymorphisme Humain (CEPH) and deCODE pedigrees; that incorporates single-nucleotide polymorphisms; and that also incorporates sequence-based positional information. The position of all markers on our map is corroborated by both genomic sequence and recombination-based data. This specific combination of features maximizes marker inclusion, coverage, and resolution, making this map uniquely suitable as a comprehensive resource for determining genetic map information (order and distances) for any large set of polymorphic markers.

Chromosome Mapping↗
PubMed2004

Retrospective characterization of Newcastle Disease Virus Antrim '73 in relation to other epidemics, past and present.

In November 1973 Newcastle disease suddenly appeared in Northern Ireland, where the viscerotropic disease had not been seen in 3 1/2 years and the two Irelands had been regarded as largely disease free for 30 years. It was successfully controlled with only 36 confirmed affected layer flocks, plus 10 more slaughtered as 'dangerous contacts'. Contemporary investigations failed to reveal the source of the Irish epidemic. Using archival virus samples from most of the affected flocks, RT PCR was conducted with primers selected for all six NDV genes. Phylogenetic analyses of three genes, HN, M and F, confirmed vaccine as the cause of one of the outbreaks. The other six samples were identical and closely related to previous outbreaks in the United States and western Europe initiated by infected imported Latin American parrots. The probable cause of the epidemic followed from the importation from The Netherlands of bulk feed grains contaminated with infected pigeon faeces.

HN Protein↗
PubMed2004

A comparison of aesthetic proportions between the Oriental and Caucasian nose.

Differences in aesthetics between the Oriental and Caucasian nose were examined from a cohort of 118 healthy volunteers of which 61 had an Oriental and 57 had a Caucasian racial origin. The oriental nose projected less from the face, and was broader at the intercanthal level (P < 0.001) and the alar base (P < 0.001), but not at the bony base. The oriental nose projected less at all levels: nasion projection (P < 0.001) and tip projection (P < 0.001). The naso-labial angles for the Orientals in this study exhibited a wider range of variation than the Caucasians, with the oriental male exhibiting the most acute angle (average 86.2 degrees ), because of the forward angulation of the upper lip. Many of the average aesthetic parameters obtained from these two cohorts of healthy subjects did not conform to the published aesthetic standards, set out as the ideal goals for rhinoplasty.

Adolescent↗
PubMed2003

Synthesis, solid-state crystal structure, and reactivity of a monomeric copper(I) anilido complex.

Synthesis and isolation of the Cu(I) amido complex (dtbpe)Cu(NHPh) (dtbpe = 1,2-bis(di-tert-butylphosphino)ethane) is accomplished upon reaction of [(dtbpe)Cu(mu-Cl)](2) with LiNHPh. The anilido complex has been fully characterized by IR spectroscopy and multinuclear NMR spectroscopy as well as by single-crystal X-ray diffraction study. Salient features of the solid-state structure include an amido orientation that allows pi-interaction of the nitrogen-based lone pair with both the empty copper p-orbital and the pi-system of the phenyl substituent. A solid-state X-ray diffraction study of [(dtbpe)Cu(NH(2)Ph)][BF(4)] has allowed a direct comparison of the structural features upon conversion of the amine ligand to an amido. The reactivity of the amido ligand of (dtbpe)Cu(NHPh) is consistent with nucleophilic character. For example, the formation of Ph(3)CNHPh is observed upon treatment with [Ph(3)C][BF(4)], and reaction at room temperature with EtX (X = Br or I) yields N-ethylaniline. The reactivity of (dtbpe)Cu(NHPh) is compared to that of the octahedral and d(6) complex TpRu(PMe(3))(2)(NHPh) (Tp = hydridotris(pyrazolyl)borate).

Journal Article↗
PubMed2003

A comparative study of the optical characteristics of commonly used sinoscopes: do you know where you are looking?

Endoscopic ethmoidectomy is a delicate operation on the thin, honey-comb-like laminae of the ethmoidal sinuses. A high degree of precision is required to minimize disruption of the natural sinus mucociliary clearance system and to reduce the risk of orbital and skull base complications. It is therefore important that surgeons are aware of variation in the optical characteristics of the rod-lens telescopes produced by different manufacturers. A simple but precision endoscope goniometer was designed and manufactured. This was used to carry out a comparative study of the sinus telescopes in common use. The results showed significant variation in the view angle of the four brands of telescopes (Karl Storz, Olympus, Richards Smith & Nephew, and Richard Wolf) tested. Differences in the position of the horizon in the visual field, and different degrees of visuospatial distortion were evident. We also noted and measured the blind angle of telescopes, which, by virtue of a high degree of angulation, cannot view the horizon.

Endoscopy↗
PubMed2003

Using human reliability analysis to detect surgical error in endoscopic DCR surgery.

The aim of this study was to describe the nature of active skill-based errors occurring in endoscopic dacrocystorhinostomy (DCR) surgery. A human reliability analysis methodology was used to assess surgical error from observational capture data. Twelve endoscopic DCR operations performed by three different surgical trainees were video recorded. The steps (subtasks) of each operation were carefully analysed and common errors were documented. Specific errors that resulted in trauma to the nasal mucosa were noted. Execution errors were common, with errors of grasping being most frequent (67% of all execution errors). Most of these involved the Blakesley forceps. In total, there were 69 mucosal trauma hits. Inserting instruments into or withdrawing them from the nasal cavity with too much force or speed caused more than half of these. Incising with too much force resulting in 'overshoot' caused 34% of mucosal trauma. Trainee ENT surgeons should take particular care when inserting or withdrawing instruments from the nasal cavity and also when performing lacrimal sac or nasal mucosa incisions. Performance of these tasks with too much force was identified as a common and potentially avoidable cause of mucosal trauma. Further research is needed into the design and use of endoscopic sinus surgery instruments with the aim of avoiding the errors that were encountered.

Dacryocystorhinostomy↗
PubMed2003

Nasal septal perforation repair using open septoplasty and unilateral bipedicled flaps.

The aim of this study was to assess the success of the technique of open septoplasty with bipedicled flaps in achieving long-term closure and control of symptoms. Between 1993 and 2000, 32 patients underwent surgery for nasal septum perforation. Twenty patients with large perforations underwent posterior edge repair only. The remaining 12 patients (five female, and seven male) with perforations less than 20 mm in diameter underwent open septoplasty and a unilateral bipedicled flap closure. A retrospective review involving a symptom scores assessment and follow-up examination was conducted. One patient died of unrelated illness, and was excluded. Results showed 10 of the remaining 11 patients achieved closure after a mean follow up of 10 months. The symptoms of crusting (p < 0.0001), epistaxis (p < 0.02), discharge (p < 0.012), whistling (p < 0.011), and overall discomfort (p < 0.02), were all significantly improved. We conclude that by using this technique on patients with small perforations less than 20 mm, it is possible to achieve up to a 90 per cent perforation closure rate, and a significant improvement in patients' symptoms.

Adult↗
PubMed2002

Bronchoscopy training: is simulated surgery effective?

Intensive surgical skills courses have become an essential part of surgical skill acquisition for surgeons in training. There is a need to monitor the value of these courses in terms of skill attainment. The aim of this study was to determine the effectiveness of skills-laboratory-based training in rigid bronchoscopy and bronchial foreign body removal. Bronchoscopies were recorded, analysed and categorized by a single observer according to time to completion and four predetermined parameters of surgical error. An overall quality score was obtained by simple summation of the number of errors and determined as acceptable or unacceptable (scoring 0 or 1 respectively). The data was analysed using a t-test for paired groups. P < 0.05 was considered to be significant. In total, 20 trainee otolaryngologists performed 80 separate bronchoscopies. The time to complete the task pre versus post training showed significant improvement; P < 0.001. The overall quality score pre training was 66 and post training 17; P < 0.001. We conclude that intensive surgical simulation-based courses appear to be an effective means of training surgical trainees in surgical skill proficiency.

Animals↗
PubMed2002

A randomized control trial of post-operative care following endoscopic sinus surgery: debridement versus no debridement.

Endoscopic sinus surgery (ESS) has undergone exponential growth worldwide in the last decade. It is now accepted as a safe and effective means of treating sinonasal disease. The purpose of this study was to determine whether post-operative debridement is necessary after ESS. Seventeen patients undergoing bilateral primary ESS were randomized to receive debridement of either the left or right ethmoid cavity. All patients included in the study had symmetrical disease. Saline douches and all other concomitant treatments were delivered bilaterally. Outcome measures were based on regular symptom scores and surgeons' semi-quantitative assessment of the debrided and non-debrided cavities, over a three-month period. Analysis of adhesion rates, healing and symptom scores showed no statistically significant difference between the two groups. In conclusion, this study did not demonstrate significant benefit from post-operative ESS cavity debridement, at least with regard to cavity healing. This should be considered a pilot study and therefore limited conclusions can be drawn. Further work is needed to determine the optimum post-operative care for ESS.

Adolescent↗
PubMed2001

Redox chemistry of morpholine-based Os(VI)-hydrazido complexes: trans-[Os(VI)(tpy)(Cl)2(NN(CH2)4O)](2+).

The oxidations of benzyl alcohol, PPh3, and the sulfides (SEt2 and SPh2) (Ph = phenyl and Et = ethyl) by the Os(VI)-hydrazido complex trans-[Os(VI)(tpy)(Cl)2(NN(CH2)4O)](2+) (tpy = 2,2':6',2' '-terpyridine and O(CH2)4N(-) = morpholide) have been investigated in CH3CN solution by UV-visible monitoring and product analysis by gas chromatography-mass spectrometry. For benzyl alcohol and the sulfides, the rate law for the formation of the Os(V)-hydrazido complex, trans-[Os(V)(tpy)(Cl)2(NN(CH2)4O)](+), is first order in both trans-[Os(VI)(tpy)(Cl)2(NN(CH2)4O)](2+) and reductant, with k(benzyl) (25.0 +/- 0.1 degrees C, CH3CN) = (1.80 +/- 0.07) x 10(-4) M(-1) s(-1), k(SEt2) = (1.33 +/- 0.02) x 10(-1) M(-1) s(-1), and k(SPh2) = (1.12 +/- 0.05) x 10(-1) M(-1) s(-1). Reduction of trans-[Os(VI)(tpy)(Cl)2(NN(CH2)4O)](2+) by PPh3 is rapid and accompanied by isomerization and solvolysis to give the Os(IV)-hydrazido product, cis-[Os(IV)(tpy)(NCCH3)2(NN(CH2)4O)](2+), and OPPh3. This reaction presumably occurs by net double Cl-atom transfer to PPh3 to give Cl2PPh3 that subsequently undergoes hydrolysis by trace H2O to give the final product, OPPh3. In the X-ray crystal structure of the Os(IV)-hydrazido complex, the Os-N-N angle of 130.9(5) degrees and the Os-N bond length of 1.971(7) A are consistent with an Os-N double bond.

Journal Article↗
PubMed2001

Synthesis, structure, and electronic properties of monomeric and dimeric trispyrazolylborate platinum(II) hydride complexes.

Tp'PtMe(H)2 (2) [Tp' = hydridotris(3,5-dimethylpyrazolyl)borate] has been prepared from Tp'PtMe(CO) (1) via reaction with water in a basic acetone/water mixture. Protonation of 2 at one of the pyrazole nitrogen atoms induces methane elimination, and the resulting platinum(II) monohydride solvent intermediate (3) can be trapped by added ligand. Two chiral cationic platinum(II) monohydride complexes of the type [kappa(2)-((Hpz)BHpz2)Pt(H)(L)][BAr'4] [L = MeCN (4), CH2=CH2 (5); pz = 3,5-dimethylpyrazolyl, BAr'4 = tetrakis(3,5-trifluoromethylphenyl)borate] have been isolated. If 2 is protonated in the absence of trapping ligand, a deep red hydride-bridged dinuclear complex, [kappa(2)-((Hpz)BHpz2)Pt(mu-H)]2[BAr'4]2 (6), forms. DFT calculations supplement intuitive expectations regarding 3-center-2-electron bridging orbital descriptions for the electronic structure of this complex. X-ray structure determinations for the monomeric acetonitrile adduct 4 and the dicationic dimer 6 are reported.

Boron Compounds↗
PubMed2001

Redox-induced terpyridyl substitution in the Os(VI)-hydrazido complex, trans-[Os(VI)(tpy)(Cl)(2)(NN(CH(2))(4)O)](2+).

Reaction between the Os(VI)-hydrazido complex, trans-[Os(VI)(tpy)(Cl)(2)(NN(CH(2))(4)O)](2+) (tpy = 2,2':6',2"-terpyridine and O(CH(2))(4)N(-) = morpholide), and a series of N- or O-bases gives as products the substituted Os(VI)-hydrazido complexes, trans-[Os(VI)(4'-RNtpy)(Cl)(2)(NN(CH(2))(4)O)](2+) or trans-[Os(VI)(4'-ROtpy)(Cl)(2)(NN(CH(2))(4)O)](2+) (RN(-) = anilide (PhNH(-)); S,S-diphenyl sulfilimide (Ph(2)S=N(-)); benzophenone imide (Ph(2)C=N(-)); piperidide ((CH(2))(5)N(-)); morpholide (O(CH(2))(4)N(-)); ethylamide (EtNH(-)); diethylamide (Et(2)N(-)); and tert-butylamide (t-BuNH(-)) and RO(-) = tert-butoxide (t-BuO(-)) and acetate (MeCO(2)(-)). The rate law for the formation of the morpholide-substituted complex is first order in trans-[Os(VI)(tpy)(Cl)(2)(NN(CH(2))(4)O)](2+) and second order in morpholine with k(morp)(25 degrees C, CH(3)CN) = (2.15 +/- 0.04) x 10(6) M(-)(2) s(-)(1). Possible mechanisms are proposed for substitution at the 4'-position of the tpy ligand by the added nucleophiles. The key features of the suggested mechanisms are the extraordinary electron withdrawing effect of Os(VI) on tpy and the ability of the metal to undergo intramolecular Os(VI) to Os(IV) electron transfer. These substituted Os(VI)-hydrazido complexes can be electrochemically reduced to the corresponding Os(V), Os(IV), and Os(III) forms. The Os-N bond length of 1.778(4) A and Os-N-N angle of 172.5(4) degrees in trans-[Os(VI)(4'-O(CH(2))(4)Ntpy)(Cl)(2)(NN(CH(2))(4)O)](2+) are consistent with sp-hybridization of the alpha-nitrogen of the hydrazido ligand and an Os-N triple bond. The extensive ring substitution chemistry implied for the Os(VI)-hydrazido complexes is discussed.

Journal Article↗
PubMed2001

Reversible osmium(VI) nitrido to osmium(II) ammine interconversion in complexes containing polypyrazolyl ligands.

This paper describes the 4e-/3H+ interconversion between NH3 and N3-, which is reversible in the coordination spheres of Os complexes containing either tpm (tpm = tris(1-pyrazolyl)methane) or Tp (Tp = hydrotris(1-pyrazolyl)borate anion) ligands. Electrochemical or chemical reduction of the nitrido complexes [Os(VI)(tpm)(Cl)2(N)]+ (1) and Os(VI)(Tp)(Cl)2(N) (2) in acidic aqueous solution gives the corresponding Os(II)-ammine complexes, which, after air oxidation and workup, are isolated and structurally characterized as [Os(III)(tpm)(Cl)2(NH3)](PF6) (3) and Os(III)(Tp)(Cl)2(NH3) (4). The Os(III)-ammine complexes are reoxidized electrochemically to the nitrido complexes by stepwise mechanisms involving the loss of both electrons and protons and sequential Os(III-->IV) and Os(IV-->VI) oxidations.

Journal Article↗