Bacterial expression of the catalytic domain of 3-hydroxy-3-methylglutaryl-CoA reductase (isoform HMGR1) from Arabidopsis thaliana, and its inactivation by phosphorylation at Ser577 by Brassica oleracea 3-hydroxy-3-methylglutaryl-CoA reductase kinase

The catalytic domain of 3-hydroxy-3-methylglutaryl-CoA reductase isoform 1 (HMGR1cd) from Arabidopsis thaliana has been expressed in Escherichia coli in a catalytically active form and purified. The high efficiency of the bacterial expression system together with the simplicity of the purification procedure used in this study resulted in the attainment of large quantities of pure enzyme (about 5 mg/l culture) with a final specific activity of up to 17 U/mg. This specific activity is higher than that reported to date for any 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) purified from a plant source. HMGR1cd activity was completely blocked by the HMGR inhibitor mevinolin (IC50 = 12.5 nM). No significant differences were observed between the Km values of HMGR1cd for NADPH (71 +/- 7 microM) and (S)-3-hydroxy-3-methylglutaryl-CoA (8.3 +/- 1.5 microM) and those of pure HMGR preparations obtained from different plant sources. The purified HMGR1cd was reversibly inactivated by phosphorylation at a single site by Brassica oleracea HMGR kinase A, which is functionally related to the mammalian AMP-activated protein kinase. The site of phosphorylation is Ser577 in the complete sequence of A. thaliana HMGR1. The results in this paper represent the first evidence that a higher plant HMGR is regulated by direct phosphorylation, at least in a cell-free system. Our results also reinforce the view that the AMP-activated protein kinase/SNF1 family is an ancient and highly conserved protein kinase system.

Similar substrate recognition motifs for mammalian AMP-activated protein kinase, higher plant HMG-CoA reductase kinase-A, yeast SNF1, and mammalian calmodulin-dependent protein kinase I

We have analysed phosphorylation of the synthetic peptide AMARAASAAALARRR, and 23 variants by mammalian, higher plant and yeast members of the SNF1 protein kinase subfamily (AMP-activated protein kinase (AMPK), HMG-CoA reductase kinase (HRK-A), and SNF1 itself), and by mammalian calmodulin-dependent protein kinase I (CaMKI). These four kinases recognize motifs which are very similar, although distinguishable. Our studies define the following recognition motifs: AMPK: phi (X beta)XXS/TXXX phi; HRK-A: phi (X,beta)XXSXXX phi; Snf1: phi XRXXSXXX phi; CaMKI: phi XRXXS/TXXX phi; where phi is a hydrophobic residue (M, V, L, I or F) and beta is a basic residue (R, K or H).

Comparison of three D-dimer assays for the diagnosis of DVT:ELISA, latex and an immunofiltration assay (NycoCard D-Dimer)

Ninety-two consecutive patients referred for suspicion of deep venous thrombosis (DVT) were analyzed for D-dimer using ELISA, latex test, and a new immunofiltration method (NycoCard D-Dimer). Contrast venography verified the diagnosis in 40, and excluded the diagnosis in 52 patients. The sensitivity, negative predictive values, specificity and positive predictive values were, for ELISA 98%, 95%, 38% and 54, for NycoCard D-Dimer 100%, 100%, 42% and 57% and for the latex test 73%, 78%, 75%, and 69%, respectively. Sensitivity and specificity were inversely related with increasing pathological cut-off value. Comparison of test results by concentration category revealed a good agreement between ELISA and NycoCard D-Dimer, but to less extent between latex and the two other tests. It is concluded that NycoCard D-Dimer and D-dimer ELISA are well-suited as exclusion tests for DVT. A plasma sample is tested with NycoCard D-Dimer in less than 2 min. Thus, this test combines advantageous analytical properties comparable to the ELISA-test, with rapidity and simplicity comparable to the latex test.

Biochemical characterization of two forms of 3-hydroxy-3-methylglutaryl-CoA reductase kinase from cauliflower (Brassica oleracia)

We recently reported the existence of a protein kinase cascade in higher plants, of which the central component is a 3-hydroxy-3-methylglutaryl(HMG-)-CoA reductase kinase functionally related to mammalian AMP-activated protein kinase [MacKintosh, R. W., Davies, S. P., Clarke P. R., Weekes, J., Gillespie, S. G., Gibb, B. J. & Hardie, D. G. (1992) Eur. J. Biochem. 209, 923-931]. We have now purified this protein kinase 9000-fold from cauliflower inflorescences. During the course of this work we noticed a second minor form (form B) which separated from the major form (A) on ion exchange and gel filtration. Both forms phosphorylate the catalytic fragment of mammalian HMG-CoA reductase. Both forms are markedly inactivated by incubation with the reactive ATP analogue p-fluorosulphonylbenzoyl adenosine (FSO2PhCOAdo), and also by mammalian protein phosphatase 2C, indicating that form B, like form A, is activated by phosphorylation. Form A has an apparent native molecular mass of 200 kDa by gel filtration and, after labelling with [14C]FSO2PhCOAdo, of 150 kDa by electrophoresis in non-denaturing gels. The catalytic subunit was identified as a polypeptide of 58 kDa after labelling with [14C]FSO2PhCOAdo. Form B has an apparent native molecular mass of 45 kDa by gel filtration, and was identified as a polypeptide of 45 kDa after labelling with [14C]FSO2PhCOAdo and [gamma-32P]ATP. Using a series of variants of the synthetic peptide substrate, the substrate specificities of the two forms are similar but not identical. Form B does not appear to be a proteolytic fragment of form A, and we therefore propose that it represents a closely related member of the same protein kinase sub-family.

Assay of D-dimer based on immunofiltration and staining with gold colloids

In this immunofiltration assay of D-dimer in plasma samples, the antigens are captured by a monoclonal antibody on a porous membrane, and labeled with the same antibody conjugated to gold colloids. The assay time is < 2 min, and a color of intensity proportional to the concentration of D-dimer is left on the membrane. The reference range (mean +/- 2 SD) was 0.336 +/- 0.133 mg/L (n = 69). Linearity was found up to 10 mg/L. Comparison with ELISA results (x) for 198 patients' samples demonstrated a linear regression equation of y = 0.99(+/- 0.05)x + 0.68(+/- 0.07) and a mean square error of 0.503. Comparison of visual reading of the color signal (y) vs reflectometric measurements (x) for 220 patients' samples demonstrated a linear regression equation of y = 2.5(+/- 0.06)x -0.22(+/- 0.04) and a mean square error of 0.095. Bilirubin, hemoglobin, fibrinogen, soluble fibrin, and fibrinogen degradation products and freezing/thawing of samples did not interfere. Some interference from rheumatoid factor, heparin, and the presence of cells or large lipid particles was seen. The variance (CV) was 8-12% within run, 10-18% between runs, and 13-20% between persons. The new assay constitutes a rapid and reliable analytical tool combining simplicity equivalent to that of latex tests with analytical information approaching that of ELISA.

Assay of D-dimer based on immunofiltration and staining with gold colloids

In this immunofiltration assay of D-dimer in plasma samples, the antigens are captured by a monoclonal antibody on a porous membrane, and labeled with the same antibody conjugated to gold colloids. The assay time is < 2 min, and a color of intensity proportional to the concentration of D-dimer is left on the membrane. The reference range (mean +/- 2 SD) was 0.336 +/- 0.133 mg/L (n = 69). Linearity was found up to 10 mg/L. Comparison with ELISA results (x) for 198 patients' samples demonstrated a linear regression equation of y = 0.99(+/- 0.05)x + 0.68(+/- 0.07) and a mean square error of 0.503. Comparison of visual reading of the color signal (y) vs reflectometric measurements (x) for 220 patients' samples demonstrated a linear regression equation of y = 2.5(+/- 0.06)x -0.22(+/- 0.04) and a mean square error of 0.095. Bilirubin, hemoglobin, fibrinogen, soluble fibrin, and fibrinogen degradation products and freezing/thawing of samples did not interfere. Some interference from rheumatoid factor, heparin, and the presence of cells or large lipid particles was seen. The variance (CV) was 8-12% within run, 10-18% between runs, and 13-20% between persons. The new assay constitutes a rapid and reliable analytical tool combining simplicity equivalent to that of latex tests with analytical information approaching that of ELISA.

Pronuclear, cleavage and blastocyst histories in the attempted preimplantation diagnosis of the human hydatidiform mole

We report a study of fertilization, syngamy and embryonic development in 14 oocytes from a woman with four previous pregnancies involving complete hydatidiform moles. Serial observations of pronuclear movements and syngamy were compared to those in a group of 10 multipronucleate embryos from other patients. One embryo and possibly two others developed normally or near-normally. The others displayed immediate cleavage or had one or three pronuclei. The tripronucleate eggs displayed various anomalous forms of growth. The unipronucleate eggs passed through a double form of syngamy, which might have involved chromosome doubling, and could have developed as androgenetic diploids. We suggest a hypothesis to explain these unusual observations.

Identification of DNA sequences flanking the breakpoint of human t(14q21q) Robertsonian translocations

We have employed molecular probes and in situ hybridization to investigate the DNA sequences flanking the breakpoint of a group of t(14q21q) Robertsonian translocations. In all the families studied, the probands were patients with Down syndrome who carried a de novo t(14q21q) translocation. The DNA probes used were two alphoid sequences, alphaRI and alphaXT, which are specific for the centromeres of chromosomes 13 and 21 and of chromosomes 14 and 22, respectively; a satellite III sequence, pTRS-47, which is specific for the proximal p11 region of chromosomes 14 and 22; and a newly defined satellite III DNA, pTRS-63, which is specific for the distal p11 region of chromosome 14. The two alphoid probes detected approximately the same amount of autoradiographic signal on the translocated chromosomes as was expected for chromosomes 14 and 21 of the originating parent, suggesting that there has been no loss of these centromeric sequences during the translocation events. Results with the two satellite III probes indicated that the domain corresponding to pTRS-47 was retained in the translocated chromosomes, whereas the domain for pTRS-63 was lost. These results have allowed us to place the translocation breakpoint between the pTRS-47 and pTRS-63 domains within the p11 region of chromosome 14.

Duplications of the X chromosome in males: evidence that most parts of the X chromosome can be active in two copies

We have analysed two duplications of the X chromosome in male patients using chromosome replication and DNA methylation patterns as determinants of the functional status of the duplicated segments. In both cases, the large duplicated regions, Xq12-q22 and Xq26.3-qter, were not inactivated. A review of previously reported male cases revealed that these duplications were also not subject to inactivation. Taken together, the examined duplications cover almost the entire X chromosome except the pericentromeric region and Xq25-26. Thus, most regions of the X chromosome can be present in two functional copies without lethal consequences.

Autoantibodies in primary biliary cirrhosis: analysis of reactivity against eukaryotic and prokaryotic 2-oxo acid dehydrogenase complexes

Six components of the mammalian 2-oxo acid dehydrogenase complexes have previously been identified as M2 autoantigens in primary biliary cirrhosis. In this report, we present data showing that both polypeptide-specific and cross-reacting antibodies are present in patients' sera. Antibodies reacting with E2 of the pyruvate dehydrogenase complex cross-react with protein X but not with any other mammalian antigen. The main immunogenic region on protein X has been localized to within its single lipoyl domain. Polypeptide-specific antibodies bind to E1 alpha and E1 beta of the pyruvate dehydrogenase complex. Antibodies reacting with the E2 polypeptides of the 2-oxoglutarate dehydrogenase complex and branched-chain 2-oxo acid dehydrogenase complex show some cross-reactivity but do not recognize any of the antigens of the pyruvate dehydrogenase complex. Antibodies against the E2 component of the mammalian pyruvate dehydrogenase complex cross-react effectively with the corresponding protein from yeast but not with E2 from Escherichia coli. Antibody titer against mammalian antigens is significantly higher than against the bacterial antigens, arguing against a bacterial origin for primary biliary cirrhosis.

Nurse, is it ME? Understanding myalgic encephalomyelitis

Ignored or dismissed for years, myalgic encephalomyelitis (ME) is now recognised as a genuine illness, and sufferers are recommended strict rest until the symptoms of the virus subside. Public understanding of ME is still uncertain, and nurses are ideally placed to provide practical information and support.

Tomography using a rotating slant-hole collimator and a large number of projections

A tomographic method using a limited-view angle has been evaluated. In studies using a gamma camera and a rotating 30-degree slant-hole (RSH) collimator, 64 projection images were registered. A special filtered backprojection technique was used for reconstruction of section images parallel to the collimator face. Resolution within such sections was 0.6 cm, 3 cm from the collimator face and 1.3 cm at 18 cm. Depth resolution was 2.2 cm at 3 cm and 5.1 cm at 18 cm. Spacing between section images was regular and geometric distortion negligible. Short-axis section images of a myocardium in vivo were qualitatively comparable or better than those obtained with single-photon emission computed tomography. Degradation in the posterior wall due to attenuation and scatter was less. Section images of the facial bones and a hip joint further demonstrated the tomographic capability of the method.

Thallium-201 myocardial tomography with a rotating slant-hole collimator and a large number of projections

Tomographic imaging of the myocardium was performed using a gamma camera and a 30-degree rotating slant-hole collimator to register 64 projections from a restricted-view angle. Section images were reconstructed with a two-dimensional filtered backprojection technique. Performance in terms of resolution, effects of misalignment, and three-dimensional activity distribution was evaluated in phantom studies. In a limited clinical study, ten consecutive patients were imaged both with single-photon emission computed tomography (SPECT) and the method described. In the new method, the camera was orientated in the 30 degrees left anterior oblique position with 15 degrees cranial tilt. Due to the short distance from the myocardium to the camera, resolution within reconstructed section images was high, the noise level was comparatively low, and the mean activity level in the posterior wall was significantly higher (p less than 0.005) than in SPECT.

Digital amputations in neuropathic feet

A retrospective study was performed on 26 patients who had undergone 27 digital amputations. All of the patients in the study had marked neuropathy. Sixty-five percent of the feet developed new ulcerations following initial hallux amputations, with 53% of the ulcerations occurring at distal digital sites. Fifty-three percent of the patients who had undergone hallux amputations required further amputations secondary to new ulcerations. In contrast, only 10% of the feet with initial lesser digit amputations developed new ulcerations. The authors discuss the biomechanics involved and the possible therapy for preventing these ulcerations and amputations.

A study of tolerance to the psychomotor effects of indomethacin in healthy volunteers

We have examined the effect of single dose indomethacin 50 mg on objective measurements of psychomotor function and whether this effect is altered by pretreatment with indomethacin 25 mg t.i.d. for 7 days in 10 healthy volunteers (5 male, 5 female; age 20-54 y). One hour after a single dose of indomethacin 50 mg there was significant impairment of psychomotor function (critical flicker fusion frequency threshold and choice reaction time) (Wilcoxon p less than 0.05). Pretreatment with indomethacin 25 mg t.i.d. for 7 days prevented this impairment. Thus we conclude that tolerance occurs over the course of a week to the psychomotor effects of indomethacin.

Amplification of satellite III DNA in an unusually large chromosome 14p+ variant

A phenotypically normal male (WSm) was found to have an unusually large short arm of chromosome 14. Increase in the size of this variant chromosome [Wsm-var(14)] was estimated to be approximately 30% that of a normal chromosome 14 by G-banding using trypsin and staining with Leishman. The extra chromosomal material was positive in CBG staining (C-banding using BaOH and staining with Giemsa), suggesting the presence of repetitive DNA. In situ hybridisation using repetitive probes demonstrated this material to be strongly positive for satellite III DNA, and negative for Y-specific heterochromatic DNA. Hybridisation with an alpha DNA probe specific for human acrocentric chromosomes indicated the retention of the centromere, and the absence of alpha DNA in the extra chromosomal material. We propose the origin of the extra chromosomal material in WSm-var(14) to be a result of amplification of contiguous satellite III DNA that is normally present in the short arm of chromosome 14. This variant chromosome does not appear to be associated with the abnormal phenotype in WSm's daughter who is mentally retarded and carries a t(1;?)(q41;?) translocation of chromosome 1.

Centromeric alpha satellite DNA amplification and translocation in an unusually large chromosome 14p+ variant

We report cytogenetic and molecular studies on a family that carries, in the father, an unusually large chromosome 14p+ variant [WSi-var(14)(p+)] and, in one of his children, a translocation [DSi-der(14)] involving the variant chromosome. Increase in the size of WSi-var(14)(p+) was estimated to be approximately 35% that of a normal chromosome 14. Presence of extra chromosomal material in this variant chromosome was demonstrated by G-banding using trypsin and staining with Leishman, G-banding using bromodeoxyuridine (BrdU) and Giemsa, and R-banding using BrdU and Giemsa. This material was positive using C-banding with BaOH and staining with Giemsa and negative in DAPI/distamycin staining, suggesting that it contained repetitive DNA but probably not of the types found in the heterochromatic regions of chromosomes 1, 9, 15, 16, and Y. Staining of the nucleolus organiser region (NOR) with AgNO3 indicated the retention of the NOR in WSi-var(14)(p+) but not in DSi-der(14). In situ hybridisation of metaphase cells with an alpha satellite DNA probe specific for human acrocentric chromosomes demonstrated a significantly increased amount of centromeric alpha sequences in WSi-var(14)(p+). Most or all of the extra alpha sequences were retained in DSi-der(14), indicating translocation near the very distal end of the enlarged region. The extra alpha satellite DNA material may have originated through amplification of some centromeric segments. The possible role of the amplified DNA in chromosomal translocations is discussed.

Inherent limitations in ectomography

Ectomography, a general tomographic method currently being implemented in nuclear medicine, is described. The object is viewed from different directions from the same projection angle, and the reconstruction process can be described as a two-dimensional filtered back-projection technique. One limitation of this limited-angle approach is that a three-dimensional Fourier representation of the acquired projections has a cone where data are missing. This empty cone can cause distortions in the tomogram by insufficient elimination of details outside the reconstructed tomographic section and by distortion of details in the section. The degree of distortion is dependent on the extension of the object in all directions and on the projection angle. Despite these limitations ectomography can be superior to single-photon-emission computed tomography for imaging sections that are close and parallel to the surface of the object, as in imaging of the hip joint or the heart.

Purification and characterization of a major allergen from the house dust mite Dermatophagoides farinae

A major allergen from an extract of the house dust mite, Dermatophagoides farinae, was shown to be extremely heterogenic with respect to charge. A slightly basic component of this allergen with a pI of 8, was purified by isoelectric focusing in two steps. The purified component, denoted antigen 19/20 IIa, seemed to be representative for the allergenic activity of the major allergen. The amino acid analysis suggested that antigen 19/20 IIa had a molecular weight of 9400 and contained one residue of galactosamine. SDS polyacrylamide gel electrophoresis did indicate a somewhat higher molecular weight of 14,500. Antibodies against the purified component cross-reacted with a crude extract of the mite Dermatophagoides pteronyssinus.

Ectomography--a tomographic method for gamma camera imaging

In computerised gamma camera imaging the projections are readily obtained in digital form, and the number of picture elements may be relatively few. This condition makes emission techniques suitable for ectomography--a tomographic technique for directly visualising arbitrary sections of the human body. The camera rotates around the patient to acquire different projections in a way similar to SPECT. This method differs from SPECT, however, in that the camera is placed at an angle to the rotational axis, and receives two-dimensional, rather than one-dimensional, projections. Images of body sections are reconstructed by digital filtration and combination of the acquired projections. The main advantages of ectomography--a high and uniform resolution, a low and uniform attenuation and a high signal-to-noise ratio--are obtained when imaging sections close and parallel to a body surface. The filtration eliminates signals representing details outside the section and gives the section a certain thickness. Ectomographic transverse images of a line source and of a human brain have been reconstructed. Details within the sections are correctly visualised and details outside are effectively eliminated. For comparison, the same sections have been imaged with SPECT.

Characterization of IgE and IgG antibody responses to Dermatophagoides farinae in rats

Rats (Brown Norway/Wistar Fu) that were pretreated or not pretreated with cyclophosphamide were immunized with varying amounts of Dermatophagoides farinae allergen extract with alum as adjuvant. Sera were analysed by RAST and by crossed radioimmunoelectrophoresis (CRIE). The highest IgE antibody responses were recorded in animals pretreated with cyclophosphamide that had received low immunizing doses of antigen. The IgE antibody pattern in CRIE was, however, not influenced by the dose of antigen or by cyclophosphamide pretreatment. The IgG pattern in CRIE closely resembled the IgE pattern, demonstrating a similar specificity of the antibody responses of the two isotypes. This indicates non-class specific control of the specificity of antibody responses.

Characterization of allergens in a crude extract of Dermatophagoides farinae and their identification in a new purified preparation

The allergens of a crude D. farinae extract were identified by means of crossed radioimmunoelectrophoresis (CRIE). A total of 11 allergens were identified. They were characterized as three major, three intermediate and five minor allergens, based on radiostaining in CRIE. In addition to the radiostaining due to allergens, some misleading radiostaining was observed associated with some of the other antigens. A purified commercially available preparation, Spectralgen Mite D. farinae, was compared with the crude extract by means of immunoelectrophoretic techniques and radioallergosorbent test (RAST) based techniques. The purified preparation was found to be fully representative of the allergens in the crude extract. All 11 allergens were identified in the purified preparation. The purification ratio of the allergens varied from 2 to 7, while the total specific allergenic activity was approximately 6 times higher in the purified preparation than in the crude extract, as judged from RAST-inhibition studies.

A new, purified Dermatophagoides farinae allergen preparation. Evaluation with SPT and RAST techniques

A purified, standardized and characterized allergen preparation of the house dust mite Dermatophagoides farinae (Df) was evaluated by skin prick test (SPT) and radioallergosorbent test (RAST) in 88 subjects. Skin reactions to the purified Df preparation and a corresponding crude Df preparation were compared. SPT was also performed with a crude Dermatophagoides pteronyssinus (Dpt) preparation to compare reactions obtained with the two mite preparations. By SPT the purified Df allergen preparation was representative of the crude Df preparation (r = 0.78) and the correlation between skin reactions to Df and Dpt was high (r = 0.78). The concordance between results obtained with RAST and SPT techniques with the purified Df preparation was high (84%). The purified D. farinae preparation was well tolerated and is well suited for SPT.

Antigens Common to Scabies and House dust Mites

Twenty-five antigens were demonstrated in a crude Dermatophagoides farinae (DF) extract by means of crossed immunoelectrophoresis (CIE), using a rabbit anti-DF serum. With the same antiserum, four antigens were demonstrated in a scabies mite preparations, indicating an immunological relationship between these scabies antigens and some of the DF antigens. In tandem CIE experiments the DF antigens were found to be partly identical to three of the scabies antigens. No IgE activity against any of these scabies antigens was evident in pooled sera from patients with house dust mite allergy by crossed radioimmunoelectrophoresis. However, one such patient had IgE antibodies to a DF antigen and a partial identical scabies antigen.

A new well-characterized, purified allergen preparation from timothy pollen. I. Chemical properties

A purified allergen preparation, Timothy N, from timothy pollen (Phleum pratense) was characterized with respect to chemical properties in comparison with a commercially available crude extract, Timothy O, from the same pollen material. In Timothy N about 94% of the protein and 99% of both hexoses and pentoses were removed during the purification. Timothy N contains a limited number of proteins with molecular weights of about 15,000 and 30,000. A Timothy N solution of 0.010 mg/ml will have an allergenic activity of 1 HEP.