Biomedical subjects
P J Brown
Publications and source records attributed to P J Brown.
Immunohistochemical characteristics of canine aortic and carotid body tumours.
In an immunohistochemical study of 25 canine chemodectomas, 17 tumours were stained with antisera to neurone specific enolase and the same number were stained for synaptophysin; a single tumour was stained for S100. Staining for Ki-67 occurred in 18 cases; the Ki-67-labelling index and the intensity of immunostaining was increased in more pleomorphic and malignant tumours, as assessed on histological grounds. Immunohistochemistry did not aid in recognition of less well-differentiated tumours.
Polyomavirus infection in hamsters and trichoepitheliomas/cutaneous adnexal tumours.
Multiple skin nodules, with histological features of adnexal tumours consistent with trichoepithelioma, were observed on the head and trunk of Syrian hamsters. Skin biopsies from 20 hamsters from five different colonies were affected, and two of the affected hamsters also had lymphoma. Two owners reported that 16 of 70 hamsters and 50 of 100 hamsters in their colonies had similar skin lesions. These tumours have previously been associated in laboratory colonies with hamster polyomavirus (HaPV) infection. Examination of skin tissues by electron microscopy failed to reveal intranuclear virus particles. Using recombinant major capsid protein VP1 of HaPV, VP1-specific antibodies were detected in sera from 12 of 12 affected hamsters and in four of four unaffected in-contact hamsters, by ELISA. The ELISA data were verified by immunoblot analysis. Eleven of 13 serum samples contained antibodies which reacted with at least one recombinant structural HaPV protein (VP2), including samples from three in-contact unaffected hamsters. Nine of the 11 anti-VP2-positive samples also reacted with recombinant VP3 of HaPV, and six reacted with VP1. Amplification by PCR and sequencing detected VP1 -encoding sequences showing a high degree of homology with HaPV. The findings suggest a possible infection by HaPV or a HaPV-like virus and it is likely that such an infection was enzootic within the affected colonies.
Sebaceous carcinoma of the salivary gland in a cat.
Sebaceous carcinoma of the submandibular salivary gland is described in a cat, tumour cells were characterized histologically by moderate amounts of pale eosinophilic or vacuolated cytoplasm. Tumour cells were stained with antibody to cytokeratins (CKs 5. 6, 8, 17 and 19) and with lectins Con A and wheat germ agglutinin (WGA); this occurs in many other types of salivary gland tumour and is a feature of normal salivary gland acinar cells.
Identification of a series of PPAR gamma/delta dual agonists via solid-phase parallel synthesis.
We have developed a general solid-phase synthesis for identification of PPAR ligands. Synthesis of a 480-member library led to the identification of a potent PPAR gamma/delta dual agonist 23. Compound 23 showed good plasma exposure in rats and demonstrated antihyperglycemic and antihyperlipidemic efficacy in diabetic fatty Zucker rats.
Nomenclature of magnetic, incommensurate, composition-changed morphotropic, polytype, transient-structural and quasicrystalline phases undergoing phase transitions. II. Report of an IUCr Working Group on Phase Transition Nomenclature.
A general nomenclature applicable to the phases that form in any sequence of transitions in the solid state has been recommended by an IUCr Working Group [Acta Cryst. (1998). A54, 1028-1033]. The six-field notation of the first Report, hereafter I, was applied to the case of structural phase transitions, i.e. to transformations resulting from temperature and/or pressure changes between two crystalline (strictly periodic) phases involving modifications to the atomic arrangement. Extensive examples that illustrate the recommendations were provided. This second Report considers, within the framework of a similar six-field notation, the more complex nomenclature of transitions involving magnetic phases, incommensurate phases and transitions that occur as a function of composition change. Extension of the nomenclature to the case of phases with less clearly established relevance to standard schemes of transition in equilibrium systems, namely polytype phases, radiation-induced and other transient phases, quasicrystalline phases and their transitions is recommended more tentatively. A uniform notation for the translational periodicity, propagation vector or wavevector for magnetic and/or incommensurate substances is specified. The notation adopted for incommensurate phases, relying partly on the existence of an average structure, is also consistent with that for commensurate phases in a sequence. The sixth field of the nomenclature is used to emphasize the special features of polytypes and transient phases. As in I, illustrative examples are provided for each category of phase sequence.
A low-temperature neutron diffraction study of Mn12-acetate.
In the low-temperature region, where the dodecanuclear mixed-valence manganese carboxylate hexadecaacetatotetraaquadodecaoxododecamanganese bis(acetic acid) tetrahydrate, [Mn(12)O(12)(C(2)D(3)O(2))(16)(H(2)O)(4)].2C(2)HD(3)O(2).4H(2)O, displays unusual magnetic properties, its structure is similar to that previously determined at room temperature [Lis (1980). Acta Cryst. B36, 2042-2046], differing only by a small change in the configuration of one of the coordinated acetate groups, related to the formation of additional hydrogen bonds, and by the orientation of the methyl groups. Since most of the magnetization density of this system resides on the Mn atoms, the consequences of these rearrangements for the magnetic properties of the compound are small.
Domains of invasion organelle proteins from apicomplexan parasites are homologous with the Apple domains of blood coagulation factor XI and plasma pre-kallikrein and are members of the PAN module superfamily.
Micronemes are specialised organelles, found in all apicomplexan parasites, which secrete molecules that are essential for parasite attachment to and invasion of host cells. Regions of several microneme proteins have sequence similarity to the Apple domains (A-domains) of blood coagulation factor XI (FXI) and plasma pre-kallikrein (PK). We have used mass spectrometry on a recombinant-expressed, putative A-domain from the microneme protein EtMIC5 from Eimeria tenella, to demonstrate that three intramolecular disulphide bridges are formed. These bridges are analogous to those that stabilise A-domains in FXI and PK. The data confirm that the apicomplexan domains are structural homologues of A-domains and are therefore novel members of the PAN module superfamily, which also includes the N-terminal domains of members of the plasminogen/hepatocyte growth factor family. The role of A-domains/PAN modules in apicomplexan parasites is not known, but their presence in the microneme suggests that they may be important for mediating protein-protein or protein-carbohydrate interactions during parasite attachment and host cell invasion.
Identification of a subtype selective human PPARalpha agonist through parallel-array synthesis.
Using solid-phase, parallel-array synthesis, a series of urea-substituted thioisobutyric acids was synthesized and assayed for activity on the human PPAR subtypes. GW7647 (3) was identified as a potent human PPARalpha agonist with approximately 200-fold selectivity over PPARgamma and PPARdelta, and potent lipid-lowering activity in animal models of dyslipidemia. GW7647 (3) will be a valuable chemical tool for studying the biology of PPARalpha in human cells and animal models of disease.
Prescribing patients out of hours.
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Avoidance of ingestion of anti-inflammatory drugs in dyspepsia is confounding variable.
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The characterization of PPAR alpha ligand drug action in an in vivo model by comprehensive differential gene expression profiling.
Expression pharmacogenomics includes differential gene expression (DGE) profiling of drug responses in model systems to generate a set of differentially modulated drug-responsive genes which can serve as a surrogate measure for drug action. In this manner, expression pharmacogenomics bridges the fields of genomics and medicinal chemistry. Additionally, modulated genes can be organized into metabolic and signaling pathways that highlight the mechanism of drug activity in a selected tissue. Here, we describe the application of expression pharmacogenomics to characterize a drug response in the clinically relevant in vivo model, the Sprague-Dawley rat. Following oral dosing of rats with GW9578, a novel synthetic peroxisome proliferator activated receptor alpha (PPAR alpha) ligand indicated for lipid disorders, we applied GeneCalling, a differential mRNA transcript profiling technique, to rat liver cDNA. Following GW9578 treatment, 2.4% of the rat liver genes were differentially expressed. We confirmed the sequence identity of 50 distinctly modulated genes. DGE was observed among genes representative of at least six discrete metabolic pathways. Furthermore, we observed up-regulation of 20 genes involved in mitochondrial, peroxisomal and microsomal fatty acid oxidation, consistent with molecular biological and clinical data indicating PPAR alpha ligand principal efficacy to be through increasing fatty acid metabolism. Those pathways regulated in our study that are potentially contributory to target effect, non-target adverse effects, or of unknown consequence include xenobiotic detoxification and steroid modification. Finally, comprehensive drug response profiling can lead to the serendipitous discovery of novel disease indications. In this case, these results suggest a potential novel indication for GW9578 in the treatment of X-linked adrenoleukodystrophy. We have shown, therefore, that the organization of DGE results into metabolic and signaling pathways can elucidate mechanisms of pharmacologically desired (i.e., efficacious) and, where appropriate, undesired (i.e., potentially deleterious) effects.
Bayesian discrimination with longitudinal data.
The motivation for the methodological development is a double-blind clinical trial designed to estimate the effect of regular injection of growth hormone, with the purpose of identifying growth hormone abusers in sport. The data formed part of a multicentre investigation jointly sponsored by the European Union and the International Olympic Committee. The data are such that for each individual there is a matrix of marker variables by time point (nominally 8 markers at each of 7 time points). Data arise out of a double-blind trial in which individuals are given growth hormone at one of two dose levels or placebo daily for 28 days. Monitoring by means of blood samples is at 0, 21, 28, 30, 33, 42 and 84 days. We give a new method of Bayesian discrimination for multivariate longitudinal data. This involves a Kronecker product covariance structure for the time by measurements (markers) data on each individual. This structure is estimated by an empirical Bayes approach, using an ECM algorithm, within a Bayesian Gaussian discrimination model. In future one may have markers for an individual at one or more time points. The method gives probabilities that an individual is on placebo or on one of the two dose regimes.
Digestive Disease Week 2000 conference report: New treatments for chronic hepatitis C.
At the Digestive Disease Week (DDW) conference and 101st Meeting of the American Gastroenterological Association in San Diego, California, May 22 to 24, 2000, over 400 abstracts on hepatitis C were submitted for posters or oral presentations to the American Association for the Study of Liver Diseases. A substantial portion of the program discussed the treatment of chronic hepatitis C, focusing on interferon and ribavirin combination therapy, substitution of amantadine for ribavirin, and the use of pegylated interferons. In randomized, clinical trials, combination therapy with interferon- alpha-2B and ribavirin results in a greater sustained virilogical response than treatment with interferon alone. Combination therapy is generally safe and well tolerated, but there is a need to monitor patients throughout treatment for hemolytic side effects, depression, and weight and lipid profiles. In the present review some background information on chronic hepatitis C is given and some of the more relevant abstracts presented on this subject at the DDW conference are highlighted.
Effects of fenofibrate on lipid parameters in obese rhesus monkeys.
Fenofibrate is a member of the fibrate class of hypolipidemic agents used clinically to treat hypertriglyceridemia and mixed hyperlipidemia. The fibrates were developed primarily on the basis of their cholesterol and triglyceride lowering in rodents. Fibrates have historically been ineffective at lowering triglycerides in experimentally-induced dyslipidemia in nonhuman primate models. The spontaneously obese rhesus monkey is a well-recognized animal model for the study of human obesity and type 2 diabetes, and many of these monkeys exhibit naturally occurring lipid abnormalities, including elevated triglycerides and low HDL cholesterol (HDL-C), similar to patients with type 2 diabetes. To explore whether the obese rhesus model was predictive of the lipid lowering effects of fibrates, we evaluated fenofibrate in six hypertriglyceridemic, hyperinsulinemic, nondiabetic animals in a 20-week, dose-escalating study. The study consisted of a 4-week baseline period, two treatment periods of 10 mg/kg twice daily (b.i.d) for 4 weeks and 30 mg/kg b.i.d. for 8 weeks, and a 4-week washout period. Fenofibrate (30 mg/kg b.i.d) decreased serum triglycerides 55% and LDL-C 27%, whereas HDL-C increased 35%. Apolipoproteins B-100 and C-III levels were also reduced 70% and 29%, respectively. Food intake, body weight, and plasma glucose were not affected throughout the study. Interestingly, plasma insulin levels decreased 40% during the 30 mg/kg treatment period, suggesting improvement in insulin sensitivity. These results support the use of obese rhesus monkey as an excellent animal model for studying the effects of novel hypolipidemic agents, particularly agents that impact serum triglycerides and HDL-C.
Data quality probes--a synergistic method for quality monitoring of electronic medical record data accuracy and healthcare provision.
Increasing reliance is being placed on electronic medical records to support clinical care and achieve improved quality standards. In order for clinical information systems (CIS) to deliver, the data within needs to be complete, consistent and accurate. This data of course only forms part of the process in delivering quality health care during the clinician-patient encounter. This paper outlines a method of assessing the quality of the processes involved in healthcare provision and data quality within a CIS. It proposes a principle of Data Quality Probes (DQP) that can be used to assess the performance of the whole encounter system. The main feature of this is the generation of a query which clinical knowledge predicts should not retrieve any cases in a system performing flawlessly. This approach is applied practically within the paradigm of a UK family practice testing the DQP that only patients who have had a hysterectomy should be prescribed unopposed oestrogen hormone replacement therapy.
Does size matter?--Evaluation of value added content of two decades of successive coding schemes in secondary care.
Over the last two decades there has been a gradual evolution from the use of simple coding schemes to controlled clinical terminologies within clinical information systems in secondary care. This evolution has required significant resources in both the development of the different coding schemes and the cost of hardware, software and human effort in implementation. During this time there has been successively larger and more complex coding schemes available for use in the UK Health Service: Read Codes 4 byte set, Read Codes 5 byte set, ICD-10 and Clinical Terms Version 3. This study evaluates what added value these successive coding schemes have offered in terms of content coverage by testing concepts derived from aClinical Information System (CIS) that has been in use to support diabetic care since 1973 (Diabeta). The schemes are quantitatively evaluated by measuring their success in providing a concept match for every notion from the CIS and their relative merits are compared. Significant added value has accrued over the years in completeness of the schemes reflected in their increased size. There appears to be justification for the continued development of clinical terminologies to support secondary care.
A geodemographic analysis of the Denplan patient population in the North West Region.
OBJECTIVE: To provide a preliminary descriptive investigation of Denplan patients in the North West Region, by plotting the age/gender and payment banding distribution, and to identify the area types where Denplan patients live and the areas in the North West Region where Denplan practices are most likely to thrive. SETTING: North West Region of England SUBJECTS AND MATERIALS: The study included Denplan patients resident in the North West Region. Age/gender and payment banding frequency distributions were constructed. A market penetration ranking report using the Target Market level of the Super Profiles geodemographic classification was produced by a spreadsheet analysis in Microsoft Excel. A Lorenz curve was plotted to graphically represent the output of the market penetration analysis. Following the market penetration analysis the enumeration districts (EDs) of the six top ranked Target Markets in the North West Region were identified and mapped out across the Region. Finally, the number and percentage of EDs in the six top ranked Target Markets were identified for each health authority in the Region. RESULTS: 47,106 patients were registered with Denplan. In all but one 5-year age band (16-20-year-olds) female patients were in the majority. Patients were concentrated (40.5%) into the 40-55 age group. Nearly 50% (22,329) of patients were allocated to the second lowest payment banding. Under 0.5% of patients (N = 199) were categorised into the highest payment band. The Target Markets at the top of the penetration ranking were more affluent in nature, with a strong rural element and an older demographic profile as part of their descriptive titles. At the bottom of the ranking deprived area types with young demographic profiles predominated. About one half (49.9%) of Denplan patients were present in just over a quarter (25.7%) of the total population of the North West Region. The Lorenz curve demonstrated that Super Profiles at Target Market level had an effectiveness of 37.9% in segmenting the population of the North West Region according to Denplan registration status. CONCLUSIONS: The population using this service in the North West Region tend to be from more mature, rural and affluent populations. The Super Profiles classification was moderately successful in segmenting the population of the North West Region according to their Denplan registration status.