Application of Bayes' to the prediction of referral decisions made by specialist optometrists in relation to chronic open angle glaucoma.

PURPOSE: To determine the accuracy of a Bayesian learning scheme (Bayes') applied to the prediction of clinical decisions made by specialist optometrists in relation to the referral refinement of chronic open angle glaucoma. METHODS: This cross-sectional observational study involved collection of data from the worst affected or right eyes of a consecutive sample of cases (n = 1,006) referred into the West Kent Clinical Commissioning Group Community Ophthalmology Team (COT) by high street optometrists. Multilevel classification of each case was based on race, sex, age, family history of chronic open angle glaucoma, reason for referral, Goldmann Applanation Tonometry (intraocular pressure and interocular asymmetry), optic nerve head assessment (vertical size, cup disc ratio and interocular asymmetry), central corneal thickness and visual field analysis (Hodapp-Parrish-Anderson classification). Randomised stratified tenfold cross-validation was applied to determine the accuracy of Bayes' by comparing its output to the clinical decisions of three COT specialist optometrists; namely, the decision to discharge, follow-up or refer each case. RESULTS: Outcomes of cross-validation, expressed as means and standard deviations, showed that the accuracy of Bayes' was high (95%, 2.0%) but that it falsely discharged (3.4%, 1.6%) or referred (3.1%, 1.5%) some cases. CONCLUSIONS: The results indicate that Bayes' has the potential to augment the decisions of specialist optometrists.

Do the vastus medialis obliquus and vastus medialis longus really exist? A systematic review.

There remains controversy over whether the vastus medialis (VM) is a single anatomical structure or whether it is composed of two separate portions, the vastus medialis longus (VML) proximally and the vastus medialis obliquus (VMO) distally. The objective of this study was to assess the evidence base of investigations into muscle fiber orientation, presence of a fibrofascial plane, and the innervation of the VM in human cadaver specimens and subjects. In addition to a hand search of specialist journals, an electronic search of AMED, British Nursing Index, CINAHL, the Cochrane database, EMBASE, ovid Medline, Pubmed, and Zetoc were performed from their inception to September 2008. All human subject papers assessing VM fiber orientation, presence of a fibrofascial plane, and the innervation of the VM where reviewed. Twenty-six papers, assessing 699 healthy knees, and 591 specimens with patellofemoral dysfunction were reviewed. The majority of nonpathological and pathological cases presented with a substantial alteration in fiber alignment seen between proximal and distal muscle portions of VM. Both cohorts presented with either one or two nerve branches to the VM. A fibrofascial plane dividing these two muscles was seen in a small proportion of both pathological and nonpathological knees. There was, however, insufficient good quality evidence to state whether the VM is composed of two separate components, the proximal VML and the distal VMO. Further study is recommended to evaluate the pathophysiological implications of such findings and to assess whether these correlate to functional electromyographic findings between the VML and VMO muscles.

Acute posterior vitreous detachment: the predictive value of vitreous pigment and symptomatology.

AIM: To establish whether the presence of a retinal break can be predicted either by the presence of a positive Shafer's sign (pigment granules in the anterior vitreous) or symptomatology in patients presenting with an acute posterior vitreous detachment (PVD). METHODS: 200 eyes of 200 phakic patients with a symptomatic PVD of less than 1 month's duration underwent documentation of symptomatology and examination of the anterior vitreous for the presence of pigment granules. Indentation ophthalmoscopy was then carried out by an experienced vitreoretinal surgeon with no knowledge of the symptomatology or anterior vitreous gel examination findings. A second prospective group of 115 consecutive patients were assessed in a similar manner before primary rhegmatogenous retinal detachment repair. RESULTS: In 200 eyes presenting with an acute PVD, 25 were found to have an associated retinal break, 23 of which were also Shafer positive. In 115 eyes presenting for retinal detachment repair, 111 had an associated PVD and were found to be Shafer positive. Symptomatology was not predictive of an associated retinal break in the PVD group or in those presenting with a retinal detachment. CONCLUSION: The increased use of Shafer's sign is recommended as a valuable aid in determining which patients require urgent referral for an expert retinal examination. It is not possible to predict those patients with a retinal break secondary to PVD on the basis of symptomatology alone.

Calcitriol and transforming growth factor-beta upregulate 5-lipoxygenase mRNA expression by increasing gene transcription and mRNA maturation.

Differentiation of the human monocytic cell line Mono Mac 6 with calcitriol plus transforming growth factor-beta (TGFbeta) strongly induces 5-lipoxygenase (5-LO) mRNA and protein expression. The mechanism of 5-LO mRNA induction by these agents was investigated. Analysis of mature 5-LO mRNA by reverse-transcriptase-PCR gave a 42-fold induction which was not due to alterations in 5-LO half life and which was only in part due to an induction of gene transcription. There was an up to fivefold increase in 5-LO primary transcripts by TGFbeta and calcitriol, which could be inhibited by cycloheximide. No significant effects on 5-LO transcription were observed with TGFbeta or calcitriol alone. However, treatment of the cells with either calcitriol or TGFbeta and addition of the corresponding second inducer lead to an about fourfold induction of primary transcript levels. Addition of cycloheximide together with the second inducer inhibited only the TGFbeta but not the calcitriol effects, which indicated that there is a direct stimulation of 5-LO transcription by calcitriol in the presence of TGFbeta-induced proteins. In order to investigate the effects of TGFbeta/calcitriol on 5-LO transcript, elongation and maturation, the relative changes in immature and mature 5-LO RNA species were analyzed by reverse-transcription-PCR. Analysis of exons 1-5 indicated an about threefold induction of 5-LO transcripts by calcitriol/TGFbeta, respectively. However, when exons 6-14 were determined, more pronounced increments were found (3.6-12-fold). Selective analysis of polyadenylated and spliced 5-LO mRNA species gave a 42-fold induction. The effects of both TGFbeta and calcitriol on transcript elongation and maturation were inhibited by cycloheximide. Our results show that induction of 5-LO mRNA by calcitriol and TGFbeta is due to a modest increase in 5-LO gene transcription and to the stimulation of transcript elongation and maturation.

Identification of penicillin allergenic determinants that bind IgE antibodies in the sera of subjects with penicillin allergy.

Much of the literature on penicillin hypersensitivity is devoted to the identification of penicillin antigens rather than allergens. Human IgE-binding determinants on different penicillins have rarely been closely investigated with the view of defining fine structural allergenic features and differences. We have developed radioimmunoassays employing ampicillin, amoxicillin and ticarcillin solid phases for the detection of penicillin-reactive IgE antibodies. Quantitative hapten inhibition studies employed to identify IgE-binding regions on the penicillin molecules revealed a heterogeneous group of allergenic determinants consisting exclusively, or in part, of the alpha-aminobenzyl and benzyl side chain groups and the beta-lactam and thiazolidine rings of the penicillin nucleus.

Immunoassays employing substituted ammonium compounds other than neuromuscular blocking drugs to increase the detection of IgE antibodies to these drugs.

Subjects who experience life-threatening anaphylactic reactions to neuromuscular blocking drugs frequently have serum IgE antibodies that react with substituted ammonium groups on the drugs. Failure to detect drug-reactive antibodies may be due to the nature of the drug-solid support used for testing sera. With this in mind, solid phases of some selected compounds containing substituted ammonium groups, in particular triethylamine and morphine, were prepared and used to screen sera in an attempt to increase the frequency of detection of IgE antibodies complementary to tertiary and/or quaternary ammonium groups. For subjects who experienced an anaphylactic reaction to succinylcholine or gallamine, use of the supplementary assays increased the frequency of detection from 83 to 100%. For d-tubocurarine and alcuronium, detections increased from 92 to 100% and from 67 to 88%, respectively. Molecular models revealed a clear structural similarity between the conformations of the trialkylammonium groups on one face of the molecules of morphine and d-tubocurarine.

The molecular basis of IgE antibody binding to thiopentone. Binding of IgE from thiopentone-allergic and non-allergic subjects.

Thiopentone-specific IgE antibodies from the sera of subjects who experienced a life-threatening anaphylactic reaction to the drug and IgE antibodies that cross-react with thiopentone via substituted ammonium groups in either cyclic or acyclic form, were studied by direct binding immunoassays and quantitative hapten inhibition methods. Findings provided an explanation for the apparent 'non-specific' nature of some IgE antibody reactions with thiopentone and reinforce the conclusion that the thiopentone IgE immunoassay is a valuable aid in the diagnosis of immediate allergic reactions to the drug.

The specificity of the binding of platelet activating factor (PAF) to anti-PAF antibodies.

Quantitative hapten inhibition experiments employing sheep anti-PAF antibodies and selected PAF analogues were undertaken with the aim of defining the antigenic determinant structures complementary to the antibody combining sites. The most important fine structural features for inhibition of antibody to PAF were shown to be an acetyl group at position 2 of the phospholipid glycerol backbone and an ether group at position 1. Of the naturally occurring compounds, C16- and C18:1-PAF proved to be the most potent inhibitors and more active than C18-PAF while phospholipids with a propionyl, butyryl or hexanoyl group at position 2 showed either weak or no inhibitory activity. The 1-acyl, thioether and deoxy analogues proved inactive. Variations in the polar head group of PAF were found to be less critical with, for example, the dimethyl and ethanolamine derivatives retaining some activity. This antibody recognition pattern is very similar to that of the PAF receptor, although the antibodies appear to have a more specific requirement for an acyl linkage at position 2.

Combining site specificities of rabbit antibodies to platelet-activating factor (PAF).

Anti-PAF sera from six different rabbits, immunized with C12- or C6-PAF as immunogen, were examined in hapten inhibition experiments in an attempt to define the fine structural recognition specificities of the antibody combining sites. Using a selection of naturally occurring lipids and PAF analogues, no significant cross-reactivity was observed with the lipids or with the inactive metabolite, lyso-PAF. Comparison of the structural specificity requirements of the antibodies from each rabbit showed some heterogeneity, with one antiserum demonstrating a different recognition specificity at position 1 on the glycerol backbone of the PAF molecule. A second rabbit antiserum showed a large degree of tolerance for analogues with increasing acyl chain length at position 2. In general, an ether group at position 1 and an acetyl at position 2 were required for inhibitory activity and a degree of tolerance was demonstrated at position 3, where the main structural requirement was for one or more methyl groups on the nitrogen atom of the phosphocholine moiety.

Drugs as allergens: an immunoassay for detecting IgE antibodies to cephalosporins.

A radioimmunoassay employing cephalothin linked to a solid phase has been developed for the detection of cephalosporin-reactive IgE antibodies. Direct binding and inhibition studies demonstrated allergenic cross-reactivity between cephalosporins and penicillins, and quantitative hapten inhibition experiments identified the 2-thiophene group, and particularly the attached methylene group, of cephalothin as an allergenic determinant.

Anaphylaxis following administration of papaveretum. Case report: Implication of IgE antibodies that react with morphine and codeine, and identification of an allergenic determinant.

IgE antibodies that reacted with morphine and codeine were detected in the serum of a subject who experienced a life-threatening anaphylactic reaction following the administration of Omnopon-Scopolamine (papaveretum-hyoscine). Hapten inhibition studies with morphine and a number of structurally-related analogues revealed that morphine and codeine were the most potent inhibitors of IgE binding to a morphine-solid phase. Nalorphine, meperidine, and methadone were also good inhibitors of IgE binding, but naltrexone, buprenorphine, and fentanyl proved to be poor inhibitors. From a detailed examination of structure-activity relationships, the authors conclude that the important structural features of the morphine allergenic (that is, IgE binding) determinant comprises the cyclohexenyl ring with a hydroxyl group at C-6 and, most important of all, a methyl substituent attached to the N atom. The authors' findings suggest that morphine analogues administered to such a patient may provoke clinical anaphylaxis. Hyoscine reacted weakly with IgE antibodies in the subject's serum, but this was thought to be due to weak cross-reaction between this compound and morphine.

Drugs as allergens: detection and combining site specificities of IgE antibodies to sulfamethoxazole.

An immunoassay was developed for the detection of sulfamethoxazole reactive IgE antibodies in the sera of patients who experienced life threatening anaphylactic reactions following the ingestion of co-trimoxazole (trimethoprim and sulfamethoxazole). Patients who had significant levels of sulfamethoxazole reactive IgE antibodies in their sera did not have IgE antibodies that reacted with trimethoprim-Sepharose. Inhibition experiments with a number of sulfonamides to determine the fine structural specificities of the sulfamethoxazole reactive IgE antibodies in three patients revealed that sulfamethoxazole and, depending on the serum, sulfamerazine and sulfamethizole, were the most potent inhibitors of IgE binding, whereas the parent sulfonamide, sulfanilamide, was a very poor inhibitor. From a detailed examination of structure-activity relationships, we concluded that the 5-methyl-3-isoxazolyl group on the sulfamethoxazole molecule was the allergenic determinant for all three patients with the 5-methyl group being particularly important for IgE antibody recognition. The assays for the detection of IgE antibodies to sulfamethoxazole and trimethoprim should prove useful for the diagnosis of immediate hypersensitivity to co-trimoxazole and perhaps for monitoring drug therapy in AIDS patients where a high incidence of adverse reactions to co-trimoxazole has been reported.

Drugs as allergens. The molecular basis of IgE binding to trimethoprim.

The combining site specificities of IgE antibodies that react with the oral antibacterial agent trimethoprim and found in the sera of two subjects who experienced anaphylaxis after taking the drug, were investigated. Hapten inhibition studies with some close analogues of trimethoprim and a range of other structurally related compounds showed that the allergenic determinant complementary to the IgE antibodies in the serum of one of the subjects was the 3,4-dimethoxybenzyl group. The complementary allergenic structure recognized by the IgE antibodies in the serum from the second subject comprised both the trimethoxybenzyl and diaminopyrimidine rings of trimethoprim. Thus, as with thiopentone, but unlike the neuromuscular blocking drugs, the trimethoprim molecule has more than one determinant each with the capacity to provoke IgE formation, interact with the antibody combining site and provoke drug-induced allergic reactions. The general approach set out here employing carefully selected structural analogues in hapten inhibition studies should be invaluable for confirming specificity and identifying allergenic determinants in IgE antibody-mediated allergic drug reactions.

Structural features of potent inhibitors of rat kidney histamine N-methyltransferase.

Three antimalarial drugs amodiaquine, quinacrine and chloroquine were compared side-by-side with the antiseptic agent chlorhexidine and the neuromuscular blocker alcuronium for their capacity to competitively inhibit in vitro the activity of the enzyme histamine N-methyltransferase (HMT) from rat kidney over the concentration range 10(-3)-10(-8). Amodiaquine was clearly the most potent HMT inhibitor followed by quinacrine, chlorhexidine, alcuronium and chloroquine. Investigation of the structure-activity relationships by examining space-filling models revealed marked similarities in the conformations of the arrangement of three N atoms in histamine and in each of the compounds tested.