Biomedical subjects
Publications and source records attributed to J R White.
We describe a patient with acute multifocal motor neuropathy with conduction block (MMNCB) and high titers of immunoglobulin G anti-GM1 antibodies after Campylobacter jejuni enteritis. Treatment with intravenous immune globulin led to rapid improvement with return of normal function by 6 weeks. This is the first report of C. jejuni enteritis preceding MMNCB.
The dose-limiting factor in essentially all curative radiotherapy is damage to normal tissue. In spite of this, our understanding of radiation-induced damage to normal tissue leaves much to be desired. Damage to the rectum is often observed after clinical brachytherapy of pelvic malignancies. A model in which the rectum of the rat is irradiated with a uniform and reproducible dose of brachytherapy irradiation was developed. This system consists of an intracavitary applicator, which is used in conjunction with methods that reduce fecal flow, a jacket that restrains rat movement and a lead-shielded chamber to contain rats during low-dose-rate brachytherapy. Irradiation was applied in 48-h intervals separated by 48-h breaks during which the applicator was removed. Methods to analyze the sequelae of brachytherapy irradiation of the rectum were also developed. The total dose of 0.75 Gy/h continuous low-dose-rate brachytherapy required to produce obstruction in the rat rectum has been measured. The ED50 was 70.6 +/- 4.2 Gy. The length of time between irradiation and obstruction was also correlated with total dose. Other effects on the rectum that were related to dose were diarrhea and rectovaginal fistula. This irradiation system can produce uniform and reliable brachytherapy doses to the rat rectum. The late effects in normal tissues observed in this model are similar to those observed in humans after irradiation of the rectum. The model should be appropriate for analyzing relative changes in the rectum resulting from different dose rates and fractionation schemes relevant to brachytherapy.
We describe the use of a gene-targeted random epitope library for the mapping of antigenic determinants. A DNA clone encoding the target antigen was digested randomly with DNase I to generate a population of DNA fragments of different sizes and sequences. After size fractionation, small DNA fragments (100-200 bp) were isolated and cloned into the phage expression vector fUSE2 to form an expression library displaying random polypeptide sequences as fusion proteins at the N terminus of the phage gene III protein. This library, termed a gene-targeted random epitope library to distinguish it from totally random synthetic epitope libraries, was then screened by affinity selection for recombinant phages which were specifically bound by the antibody of interest. Using this approach, we have mapped a monoclonal antibody (mAb)-defined epitope on the bluetongue virus outer capsid protein VP5. This epitope is not accessible on the intact virus surface, but is recognised by the immune system of sheep and cattle during virus infection. Although the example given here utilised a DNA fragment of known sequence and the library was screened for a mAb-defined epitope, the strategy described should be equally applicable to genes of unknown sequence and for screening of epitopes using polyclonal antibodies. The approach can also be extended to identify immunodominant epitope from much more complex genome-targeted random epitope library for virus, bacteria and eukaryotic organisms. Other applications of recombinant phages expressing defined immunodominant epitopes include serodiagnosis and vaccine development.
Monoclonal antibodies (mAbs) were raised to a preparation of rabbit haemorrhagic disease virus (RHDV) purified from the livers of experimentally infected rabbits. Rabbit antisera to RHDV significantly blocked the binding of two mAbs (2D3(3) and 2D4(5)) to RHDV-coated microplate wells in a competition ELISA. The virus-specific nature of these mAbs was confirmed by immunoperoxidase and immunofluorescence assays on formalin-fixed and fresh infected liver tissue. Utilization of one of these mAbs (2D3(3)) in a competition ELISA, resulted in an RHDV antibody assay which proved more specific than an indirect ELISA and more rapid and reliable than a haemagglutination inhibition assay for screening serum samples from wild and experimental rabbits.
The myelodysplastic syndromes (MDS) have a significant frequency of evolution into acute myeloid leukaemia (AML). Approximately 30% of MDS patients show activating mutations of the N-RAS proto-oncogene, and these patients are at increased risk of leukaemic evolution. Long-term survivors of aplastic anaemia (AA) and paroxysmal nocturnal haemoglobinurea (PNH) are also at significant risk of developing AML. We have screened peripheral blood DNA from 42 AA patients and 15 PNH patients for the presence of N-RAS point mutations. No mutations were detected in these samples, indicating that the mechanisms of evolution into AML may be different from those in MDS.
The ability of an ELISA-based system to reliably assess the relative affinities of separate monoclonal antibodies (MAbs) for heterologous isolates of bluetongue virus (BTV) was tested. The demonstration that a BTV serogroup-specific MAb (20E9B7G2) possessed equivalent binding properties with the majority of virus isolates tested, permitted a reliable estimation of the relative amount of individual test viruses present in the assay. Subsequent correction for the relative amounts of test viruses and homologous virus present, then allowed monoclonal antibody affinities for heterologous virus isolates to be quantitatively expressed as a function of their homologous binding level and enabled comparisons of individual MAb affinities between virus isolates to be made.
Interleukin-8 has been shown by X-ray crystallography and NMR to be a homodimer, suggesting that this is the form which binds to its receptor. Here we measure, for the first time, the monomer-dimer equilibrium of interleukin-8 using analytical ultracentrifugation and titration microcalorimetry and find that it dissociates readily to monomers with an equilibrium dissociation constant of 18 +/- 6 microM at 37 degrees C. The present findings suggest that the monomer is the form which binds to the receptor. Comparison of experimental and structure-based calculated thermodynamics of interleukin-8 dimerization argues for limited subunit conformational changes upon dissociation to monomer.
BACKGROUND: The authors have reviewed their institution's experience with conservative surgery and radiation therapy for early stage breast cancer with the goal of defining the impact of infiltrating lobular histology (ILC) on the local recurrence rate. Also, they have examined the preoperative mammograms of the ILC patients to determine if mammographic features could be used to predict treatment outcome. METHODS: Between January 1, 1980, and December 31, 1987, 402 cases of Stages I and II breast cancer were treated with conservative surgery and radiation therapy (BCT) at William Beaumont Hospital. Each patient had at least an excisional biopsy. Radiation consisted of 45-50 Gy to the entire breast followed by a supplemental boost dose, so that a minimum of 60 Gy was delivered to the tumor bed. Thirty cancers were classified histologically as infiltrating lobular carcinoma (ILC), 346 as infiltrating ductal carcinoma (IDC), and 26 as other. Median follow-up is 60 months. RESULTS: There was no significant difference in 5 year actuarial local recurrence rates between ILC and IDC, 3.3 versus 4.2%, respectively, (P = not significant). Preoperative mammograms were retrospectively reviewed for 29 of the 30 ILC patients. A spiculated opacity was the most common primary mammographic finding (63%), followed by architectural distortion (17%), poorly defined opacity (7%), and negative (7%). Of the patients who had a preoperative primary mammographic finding of a spiculated opacity, 55% underwent reexcision after the initial excisional biopsy, and residual invasive carcinoma was found in 18% of the reexcision specimens. In contrast, of the patients with a primary mammographic finding of an architectural distortion, poorly defined opacity, or negative, 89% underwent reexcision after an initial excisional biopsy, and residual invasive carcinoma was found in 100% of the reexcision specimens. CONCLUSIONS: Infiltrating lobular carcinoma does not have a worse local recurrence rate compared with IDC when each is treated with breast-conserving therapy. The primary finding on preoperative mammograms in patients with ILC may prove to be a useful tool for predicting the likelihood of residual carcinoma in the breast after initial excisional biopsy.
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This communication describes the development and evaluation of a simple and rapid method for the classification of Australian orbiviruses into one of seven established serogroups (i.e. bluetongue, epizootic haemorrhagic disease of deer, Palyam, Eubenangee, Corriparta, Wallal, Warrego) or an 'ungrouped' category. The Australian orbivirus serogrouping ELISA (SG-ELISA) utilised a sodium deoxycholate-treated cell lysate preparation from infected BHK cells which was subsequently probed in an indirect ELISA format with polyclonal antibodies representative of each serogroup. Bound immunoglobulin was detected by the use of a recombinant streptococcal protein G-HRPO conjugate and subsequent reaction with the chromogenic substrate. All reference orbiviruses tested in the SG-ELISA were identified and were in agreement with the serogroups originally designated. Minimal inter-serogroup cross-reactions were observed. One-way cross-reactions were observed between Warrego and Mitchell River viruses.
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Explore the source record for details and available documents.
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Any number of prescription and over-the-counter medications, including diuretics and salicylates, can affect glycemic control in diabetic patients. In addition, patients being treated with either insulin or sulfonylurea risk hypoglycemic coma or death if they ingest large quantities of alcohol. The authors of this article discuss the medications most likely to be a problem and provide lists of agents associated with hypoglycemia and hyperglycemia.
The antiinflammatory activity of rolipram, a selective inhibitor of the cyclic AMP-specific phosphodiesterase (PDE IV), was studied. Rolipram did not inhibit 5-lipoxygenase activity but did inhibit human monocyte production of leukotriene B4 (LTB4, IC50 3.5 microM). Likewise, murine mast cell release of leukotriene C4 and histamine was inhibited. In vivo, rolipram inhibited arachidonic acid-induced inflammation in the mouse, while the low Km-cyclic-GMP PDE inhibitor, zaprinast, did not inhibit. Rolipram had a modest effect on LTB4 production in the mouse, but markedly reduced LTB4-induced PMN infiltration. Beta-adrenergic receptor activation of adenylate cyclase was important for rolipram antiinflammatory activity since beta blockade abrogated arachidonic acid-induced inflammation. Thus, the antiinflammatory profile of rolipram is novel and may result from inhibition of PMN function and perhaps vasoactive amine release and leukotriene biosynthesis. These actions may be dependent upon endogenous beta-adrenergic activity and are likely mediated through inhibition of PDE IV.
Several protein kinase inhibitors (PKIs) were investigated for their effects on IL-1 beta, TNF alpha and PMA-induced IL-8 production from human umbilical vein endothelial cells (HUVEC). IL-1 beta (ED50 0.07 ng/ml), TNF alpha (ED50 100 ng/ml) and PMA (ED50 20 ng/ml) induced IL-8 production that could be detected as early as 2 h following stimulation. Staurosporine, a potent but non-specific inhibitor of protein kinases, inhibited PMA-induced (IC50 2 nM) but not IL-1 beta or TNF alpha (IC50 > 200 nM) induced IL-8 production. Neither the cAMP-dependent PKI, KT5720, nor the tyrosine PKIs, genistein, tyrphostin (1-100 microM) or lavendustin A (0.0001-1 microM), inhibited IL-8 production elicited by IL-1 beta. However, the macrolide protein kinase inhibitor geldanamycin (IC50 = 30 nM), but not the closely related analog herbimycin A (5-500 nM), inhibited IL-8 production by 60%. Northern blot analysis of IL-8 mRNA revealed that staurosporine suppressed mRNA increase following stimulation by PMA but not by IL-1. It is proposed that a novel protein kinase susceptible to geldanamycin inhibition may be involved in IL-1-mediated signal transduction.
Peptides were synthesized, that correspond to cleaved and trimmed carboxyl termini of the F2 polypeptide regions of fusion (F) protein precursors (F0 proteins) in four different strains of Newcastle disease virus (NDV). These peptides differed only within the four carboxyl-terminal residues and represent F2 polypeptides of virulent (AV), low-virulence (EG) and avirulent (V4 and WA) pathotypes of NDV. Polyclonal rabbit antisera against each peptide reacted with their corresponding monomeric F2 polypeptides and F protein oligomers as analysed by immunoblotting of egg-propagated virions. Bidirectional cross-reactivity was observed between V4 and EG antisera and F2 polypeptides which differ only by a single variation of lysine and arginine at position 3 from their carboxyl termini. The other two antisera (AV and WA) were specific for their corresponding F2 polypeptides. All of these antisera were shown to react in a strain-specific manner with intact egg-propagated virions in an ELISA. A previously described antiserum, designed to target the haemagglutinin-neuraminidase (HN) protein precursor (HN0 protein) of avirulent strains of NDV, has been shown to be specific for residual HN0 protein of avirulent virions propagated in embryonated chicken eggs. Whereas the antiserum targeted at the carboxyl terminus of the V4 F2 polypeptide did not react with F0 proteins of cell culture-propagated strains in immunoblotting, antipeptide antibodies targeted at another region of the F2 polypeptide and a segment of the F1 polypeptide did react with the F0 protein from infected cells. These data are consistent with inclusion of the terminal carboxylate of the F2 polypeptides in the recognition determinants of the antibodies targeted at the carboxyl terminus of the V4 F2 polypeptide. The antisera described herein are ideally suited to rapid immunochemical pathotyping of NDV isolates and immunochemical characterization of the sites of intracellular cleavage activation of F0 and HN0 proteins and may be useful for defining interactions involved in F protein folding.
OBJECTIVE: To discuss the potential link between diabetes mellitus (DM) and hypomagnesemia, the methods used to assess magnesium status, and the potential benefits of magnesium repletion in hypomagnesemic patients with DM. DATA SOURCES: A MEDLINE search (key terms: magnesium and diabetes) was conducted to identify pertinent literature. STUDY SELECTION: All major clinical trials and most published case reports were reviewed. SYNTHESIS: Several studies have demonstrated a higher than expected frequency of magnesium deficiency in patients with DM. Hypomagnesemia may play a role in the development of retinopathy, altered glucose disposition, hypertension, abnormal platelet function, and other problems frequently observed in patients with DM. The lack of a widely available, accurate screening methodology is one of the main problems in assessing total body magnesium status. One study has suggested that hypomagnesemia in patients with DM may be related to enhanced urinary loss of magnesium. Several studies evaluating hypomagnesemia and glucose disposal have suggested a direct correlation between magnesium concentration and glucose disposal, with an improvement in glucose disposal with magnesium supplementation. It has been suggested that there is a relationship between hypomagnesemia and diabetic retinopathy; however, the effect of magnesium supplementation on the development of diabetic retinopathy has not been evaluated. Researchers evaluating the effect of magnesium on platelet aggregation have suggested that magnesium supplementation may reduce the incidence of vascular disease in hypomagnesemic patients with DM. Several studies have demonstrated a correlation between hypomagnesemia and hypertension. CONCLUSIONS: Studies have suggested a link between hypomagnesemia and hyperglycemia, as well as an association between hypomagnesemia and the complications of DM. The American Diabetes Association has published a consensus statement suggesting that patients who have documented hypomagnesemia and DM receive magnesium supplementation.