Transcriptomic Impact of IMA-08401, a Novel AHR Agonist Resembling Laquinimod, on Rat Liver

IMA-08401 (C2) is a novel aryl hydrocarbon receptor (AHR) agonist and selective AHR modulator (SAHRM) that is structurally similar to laquinimod (LAQ). Both compounds are converted to the AHR-active metabolite DELAQ (IMA-06201) in vivo. SAHRMs have been proposed as therapeutic options for various autoimmune disorders. Clinical trials on LAQ have not reported any significant toxic outcomes and C2 has shown low toxicity in rats; however, their functional resemblance to the highly toxic AHR agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) raises questions. Here, we characterize the hepatic transcriptomic changes induced by acute (single-dose) and subacute exposure (repeated dosing for 5 days followed by a 5-day recovery period) to C2 in Sprague-Dawley rats. Exposure to C2 leads to activation of the AHR, as shown by altered transcription of Cyp1a1. We identify a heightened response early after exposure that drops off by day 10. Acute exposure to C2 leads to changes to transcription of genes involved in antiviral and antibacterial responses, which highlights the immunomodulator effects of this AHR agonist. Subacute exposure causes an oxidative stress response in the liver, the consequences of which require further study on target tissues such as the CNS and immune system, both of which may be compromised in this patient population.

Toxicological characterisation of two novel selective aryl hydrocarbon receptor modulators in Sprague-Dawley rats

The aryl hydrocarbon receptor (AHR) mediates the toxicity of dioxins, but also plays important physiological roles. Selective AHR modulators, which elicit some effects imparted by this receptor without causing the marked toxicity of dioxins, are presently under intense scrutiny. Two novel such compounds are IMA-08401 (N-acetyl-N-phenyl-4-acetoxy-5-chloro-1,2-dihydro-1-methyl-2-oxo-quinoline-3-carboxamide) and IMA-07101 (N-acetyl-N-(4-trifluoromethylphenyl)-4-acetoxy-1,2-dihydro-5-methoxy-1-methyl-2-oxo-quinoline-3-carboxamide). They represent, as diacetyl prodrugs, AHR-active metabolites of the drug compounds laquinimod and tasquinimod, respectively, which are intended for the treatment of autoimmune diseases and cancer. Here, we toxicologically assessed the novel compounds in Sprague-Dawley rats, after a single dose (8.75-92.5mg/kg) and 5-day repeated dosing at the highest doses achievable (IMA-08401: 100mg/kg/day; and IMA-07101: 75mg/kg/day). There were no overt clinical signs of toxicity, but body weight gain was marginally retarded, and the treatments induced minimal hepatic extramedullary haematopoiesis. Further, both the absolute and relative weights of the thymus were significantly decreased. Cyp1a1 gene expression was substantially increased in all tissues examined. The hepatic induction profile of other AHR battery genes was distinct from that caused by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The only marked alterations in serum clinical chemistry variables were a reduction in triglycerides and an increase in 3-hydroxybutyrate. Liver and kidney retinol and retinyl palmitate concentrations were affected largely in the same manner as reported for TCDD. In vitro, the novel compounds activated CYP1A1 effectively in H4IIE cells. Altogether, these novel compounds appear to act as potent activators of the AHR, but lack some major characteristic toxicities of dioxins. They therefore represent promising new selective AHR modulators.

Viral load and humoral immune response in association with disease severity in Puumala hantavirus-infected patients--implications for treatment

Hantaviruses are the causative agents of haemorrhagic fever with renal syndrome (HFRS) in Eurasia and of hantavirus cardiopulmonary syndrome (HCPS) in the Americas. The case fatality rate varies between different hantaviruses and can be up to 40%. At present, there is no specific treatment available. The hantavirus pathogenesis is not well understood, but most likely, both virus-mediated and host-mediated mechanisms are involved. The aim of the present study was to investigate the association among Puumala hantavirus (PUUV) viral RNA load, humoral immune response and disease severity in patients with HFRS. We performed a study of 105 PUUV-infected patients that were followed during the acute phase of disease and for up to 1–3 months later. Fifteen of the 105 patients (14%) were classified as having moderate/severe disease. A low PUUV-specific IgG response (p <0.05) and also a higher white blood cell count (p <0.001) were significantly associated with more severe disease. The PUUV RNA was detected in a majority of patient plasma samples up to 9 days after disease onset; however, PUUV RNA load or longevity of viraemia were not significantly associated with disease severity. We conclude that a low specific IgG response was associated with disease severity in patients with HFRS, whereas PUUV RNA load did not seem to affect the severity of HFRS. Our results raise the possibility of passive immunotherapy as a useful treatment for hantavirus-infected patients.

A critical investigation of ISO 11948-2 and ISO 11948-1 for predicting the leakage performance of small disposable incontinence pads for lightly incontinent women

ISO 11948-2--an international standard laboratory method developed to predict the leakage performance of small disposable pads for lightly incontinent women--was investigated. The repeatability and reproducibility (precision within and between laboratories, respectively) of two variants on the method were found to be poor. The coefficient of variation for each method variant in each laboratory (two laboratories ran each variant) was higher than 40% for about half the 12 products evaluated. Results differed by up to 94% between laboratories for a given product. The ability of the method to predict the leakage performance of pads was investigated by measuring correlations between the clinical evaluations of the 12 products, and technical evaluations using ISO 11948-2. Correlations were very weak (r < or= 0.487). Accordingly, it is recommended that 11948-2 is withdrawn. A second international standard method (ISO 11948-1)--developed for evaluating large pads, but sometimes used on small ones--was also investigated. Correlations between the clinical evaluations of the 12 products and technical evaluations using ISO 11948-1 were weak (r < or = 0.560). Accordingly, it is recommended that ISO 11948-1 is not used for evaluating small disposable bodyworn pads for women.

How well does ISO 11948-1 (the Rothwell method) for measuring the absorption capacity of incontinence pads in the laboratory correlate with clinical pad performance

The ability of ISO 11948-1 (the Rothwell method) to predict the leakage performance of disposable bodyworn pads for heavy urinary incontinence was investigated by measuring correlations between models based on clinical evaluations of 138 diapers and inserts (the two major design categories), and technical models based on their Rothwell absorption capacities and design features. Correlations were poorer than in the original 1993 study for the standard (r < or =0.87 compared with r < or =0.95), but still strong enough to help with purchasing choices. For a given Rothwell capacity, the leakage performance of diapers was far superior to inserts; for example, diapers containing 450 and 300 g of urine performed, as well as inserts containing 300 and 100 g, respectively. No evidence was found for any other design feature having a significant impact on leakage performance. The coefficient of variation for Rothwell capacity (a measure of product consistency) had significant impact on the leakage performance of diapers, but not inserts. The probability of diapers with the poorest consistency leaking exceeded that for the best by about 10 percentage points. Similarly, diapers were about 10 percentage points more likely to leak when used at night than during the day. Differences between day-time and night-time use of inserts were not studied.

Normal size of the lumen of the aorta in dwarf mice lacking IGF-II

The peptide insulin-like growth factor II (IGF-II) is a foetal promoter of growth and differentiation. Genetically modified mice have provided insights into the contribution of IGF-II to the determination of the size of the body and individual organs. Nevertheless, the role of IGF-II in regulating the size of major blood vessels is poorly understood. Here, the transverse luminal and medial area of the aorta and the number of medial cell nuclei are shown not to be significantly different in adult wild-type and Igf2 nullizygous mice, despite a approximately 30% reduction in BW in the latter group. The observations in this study suggest that IGF-II is not an indispensable factor in the determination of the size of the aortic lumen, and are consistent with the view that growth factor redundancy may be a safeguard mechanism to maintain the size of the aorta within a range compatible with viability.

Coated catheters for intermittent catheterization: smooth or sticky?

OBJECTIVE

To evaluate the current range of hydrophilic-coated catheters for intermittent self-catheterization, focusing on the adherence of the catheter to the urethral mucosa at the end of catheterization.

PATIENTS AND METHODS

In a prospective randomized study, 61 community-based men tested each of four different hydrophilic-coated catheters available in the UK at the time. Subjects used each of the four test catheters for 1 week in a random order, and were provided with the number and size of catheter they normally used. To assess the products, the subjects: (i) timed seven catheterizations using a stop-watch to determine the time taken from extracting the catheter from the water-filled package, to removing the catheter from the penis, having emptied the bladder; (ii) recorded the severity of 'sticking' on catheter removal on a three-point scale (not at all, a little, a lot); and (iii) completed a product-performance questionnaire.

RESULTS

There were no significant differences in ratings of 'sticking' between the 'Easicath' and 'Lofric' (P > 0.05), but there were significant differences between these two products and the 'Aquacath' and the 'Silky', which were found to 'stick' more (P < 0.001). The 'Silky' was reported to stick significantly more than the 'Aquacath' (P < 0.001).

CONCLUSIONS

Adherence to the urethral mucosa on catheter removal was a common problem, occurring with all catheters, but two products were significantly more likely to stick than the other two. The clinical importance of 'sticking' and the long-term implications are currently unknown. The relative 'sticking' of uncoated catheters has also not been established.

Sheaths for urinary incontinence: a randomized crossover trial

OBJECTIVE

To evaluate the full range of self-adhesive continence sheaths for men available in the UK and thus provide clinicians and consumers with a basis for product selection.

PATIENTS AND METHODS

Fifty-eight volunteers (aged 30-89 years) tested each of six different self-adhesive sheaths available in the UK in September 1998 for 1 week each. Thirty subjects applied the sheaths themselves and 28 subjects relied on a carer to do so. During each week subjects completed a diary recording sheath changes and the result of skin inspection, to note any unscheduled sheath changes (because of sheath detachment) and any skin problems. At the end of each week an 11-item questionnaire was completed using a three-point rating scale ('good', 'acceptable', 'unacceptable') to assess the key aspects of product performance.

RESULTS

A significantly higher proportion of subjects scored the 'Aquadry Clear Advantage' sheath as 'good' than four of the other sheaths (P < 0.01) and a significantly higher proportion found the 'Incare' sheath to be 'unacceptable' than all of the other sheaths (P < 0.001) for the 'overall opinion' question. Sheath detachments (sheath falling off or blowing off) for the 'Incare' were significantly more common than for four of the other products (P < 0.01). Sheath detachments for the 'Aquadry Clear Advantage' were significantly less common than for two of the other products (P < 0.01). A significantly higher proportion of subjects found sheaths with an applicator to be 'unacceptable' than sheaths with no applicator (P < 0.001) for the 'ease of putting on' and 'overall opinion' questions (when adjusted for previous product use and person applying the sheath).

CONCLUSIONS

There were substantial differences between products in their general performance and ergonomics, and for the frequency of detachment as recorded in the diary. The 'Aquadry Clear Advantage' was particularly successful and the 'Incare' particularly unsuccessful when compared with the other sheaths. Sheaths with no applicators were preferred to those with applicators. Applicators are mainly designed to make sheaths easier to put on, especially for carers, but there was no evidence that carers preferred applicators. This may have implications for manufacturers.

Multicomponent polyanions. 57. Large-angle X-ray scattering study of aqueous molybdophenylphosphonate solutions

The radial distribution functions are calculated from large-angle X-ray scattering (LAXS) measurements for one concentrated aqueous molybdate/heptamolybdate solution and five aqueous molybdophenylphosphonate solutions (lithium chloride medium). Besides water and hydrated lithium, chloride, and molybdate ions, five species in all, having different nuclearities, are postulated to exist in the solutions, according to equilibrium studies using potentiometry and 31P NMR spectroscopy. The structures of the three polymolybdate species Mo7O24(6-), Mo8O26(4-), and (C6H5P)2Mo5O21(4-), for which the structures are determined crystallographically, are confirmed to exist also in aqueous solution. The principal structures of the remaining two complexes, (C6H5P)Mo6O21(OH2)5(2-) and (C6H5P)Mo7O25(OH2)4-, are elucidated with the use of structures of related species. Both anions have one group of four edge-sharing MoO6 octahedra and another group of two MoO6 octahedra connected by sharing corners, forming a bent unsymmetric six-membered ring, with the C6H5PO3 group placed on the crowded side of the ring. In the former, the group of two MoO6 octahedra is edge-shared, while in the latter, the group is face-shared, resulting in a ring small enough to tetrahedrally coordinate to the seventh molybdenum opposite the phenyl group.

A potentiometric and 51V NMR study of the aqueous H+/H2VO4-/H2O2/L-alpha-alanyl-L-histidine system

The speciation in the quaternary aqueous H+/H2VO4-/H2O2/L-alpha-alanyl-L-histidine (Ah) system has been determined from quantitative 51V NMR measurements and potentiometric data (glass electrode). The study was performed in 0.150 M Na(Cl) medium at 25 degrees C. Data were evaluated with the computer program LAKE, which is able to treat combined EMF and NMR data. The pKa values for Ah were determined as 8.06, 6.72 and 2.64. In the ternary H+/H2VO4-/Ah system, two complexes, (H+)p(H2VO4-)q(Ah)r, for which (p, q, r) values of (0, 1, 1) and (1, 1, 1) with log beta(0,1,1) = 2.52 +/- 0.03 and log beta(1,1,1) = 9.40 +/- 0.05 (pKa = 6.88), respectively, explain all data. The errors given are 3sigma. In the quaternary H+/H2VO4-/H2O2/Ah system, eight complexes were determined in addition to all binary and ternary complexes, four with a V/X/Ah ratio 1:1:1 and four with a ratio 1:2:1 (X = peroxo ligand). VX2Ah2- and VX2Ah- (pKa = 8.19) are the main complexes and predominate in the pH range 5 to 9. Three additional minor species have also been found but their compositions could not be determined owing to their small amounts. Equilibria are slow, significant decomposition of peroxide occurs only in acidic solutions. Data in the pH range 5 to 10 have been used for the LAKE calculations. Chemical shifts, compositions, and formation constants for the eight quaternary complexes are given, and equilibrium conditions are illustrated in distribution diagrams. Structural proposals for VX2Ah2- and VX2Ah- are made from 1H and 13C NMR measurements.

Speciation in vanadium bioinorganic systems. 6. Speciation study of aqueous peroxovanadates, including complexes with imidazole

Using a combination of potentiometry (glass electrode) and quantitative 51V NMR spectroscopy, the full speciation in the vanadate-peroxide and vanadate-peroxide-imidazole systems was determined in the pH range 1-10 (0.150 M Na(Cl) medium, 25 degrees C). Using the computer program LAKE, the pKa value of imidazole and the formation constants for 10 peroxovanadate species and also for three more species where a single imidazole moiety is also bound, have been calculated. The experimental data show a good fit to the calculated speciation model, even for the less abundant species. The species are either monomeric or dimeric in vanadium, and four resonances of the dimeric species have been unambiguously assigned via 2D 51V NMR. Diperoxovanadates are the favoured species at pH 2-10, when sufficient peroxide is present. Imidazole is found to bind strongly to them at pH 6-9. The equilibrium conditions are illustrated in distribution diagrams.

Speciation in the vanadate-alanylhistidine-peroxide system

The speciation in the quaternary aqueous H+-H2VO4(-)-H2O2-L-alpha-alanyl-L-histidine (Ah) system has been determined from quantitative 51V NMR measurements and potentiometric data (glass electrode). The study was performed in 0.150 M Na(Cl) medium at 25 degrees C. Data were evaluated with the computer program LAKE, which is able to treat combined potentiometric and NMR data. In the ternary H+-H2VO4(-)-Ah system, two complexes, (H+)p(H2VO4-)q(Ah)r, having (p, q, r) values (0, 1, 1) and (1, 1, 1) (pKa = 6.88) explain all data. In the quaternary H+-H2VO4(-)-H2O2-Ah system, seven complexes were determined in addition to all binary and ternary complexes, four with a V/X/Ah ratio 1:1:1 and three with a ratio 1:2:1 (X = peroxo ligand). VX2Ah2- and VX2Ah- (pKa = 8.26) are the main quaternary complexes and predominate in the pH range 5 to 9. Chemical shifts, compositions and formation constants for all the quaternary complexes are given, and equilibrium conditions are illustrated in distribution diagrams.

Chromosomal breakage-fusion-bridge events cause genetic intratumor heterogeneity

It has long been known that rearrangements of chromosomes through breakage-fusion-bridge (BFB) cycles may cause variability of phenotypic and genetic traits within a cell population. Because intercellular heterogeneity is often found in neoplastic tissues, we investigated the occurrence of BFB events in human solid tumors. Evidence of frequent BFB events was found in malignancies that showed unspecific chromosome aberrations, including ring chromosomes, dicentric chromosomes, and telomeric associations, as well as extensive intratumor heterogeneity in the pattern of structural changes but not in tumors with tumor-specific aberrations and low variability. Fluorescence in situ hybridization analysis demonstrated that chromosomes participating in anaphase bridge formation were involved in a significantly higher number of structural aberrations than other chromosomes. Tumors with BFB events showed a decreased elimination rate of unstable chromosome aberrations after irradiation compared with normal cells and other tumor cells. This result suggests that a combination of mitotically unstable chromosomes and an elevated tolerance to chromosomal damage leads to constant genomic reorganization in many malignancies, thereby providing a flexible genetic system for clonal evolution and progression.

The selection of female urinals: results of a multicentre evaluation

Female urinals are designed to enable women to empty their bladders while not on the toilet and are therefore potentially useful in preventing incontinence. However, there is little published information to guide product selection. Therefore, an evaluation of these products was undertaken by the Continence Products Evaluation Network (funded by the Medical Devices Agency). All 13 reusable female urinals available in the UK in March 1997 were evaluated. Each urinal was evaluated by 28-32 community-based women. Preliminarily, each subject tested all urinals by trying to place them in one or two of their preferred positions, to establish if the urinals were suitable for full testing. Each of the urinals that were selected for full testing were then used for 1 week each. During this week the subjects kept a diary to record leakage or spillage when using the urinal. At the end of the week a product evaluation form was filled in to record product performance. The results from full testing indicate that all urinals were successful for some subjects. However, some urinals were found to be successful for all four main positions (e.g. Petal Female Urinal) while others were successful mainly in one or two positions (e.g. Bridge Saddle Pan and Subaseal). Many urinals were successful in the standing/crouching and sitting on the edge (of chair or bed) positions, while comparatively few urinals were successful in the lying position. It was found that the chances of finding a suitable urinal increased with levels of independence. This means that subjects with higher levels of dependency found fewer urinals to be suitable for their needs when used without assistance. The results of this evaluation provide guidance for product selection. However, it is recommended that continence specialists keep samples of the full range of female urinals to enable women to experiment with urinals in order to find one that best suits their needs.

Novel and classical protein kinase C isoforms have different functions in proliferation, survival and differentiation of neuroblastoma cells

To elucidate the possibility of utilizing protein kinase C (PKC) isoforms as target genes in neuroblastoma therapy, 5 neuroblastoma cell lines and neuroblastoma tumor specimens were examined for PKC isoform expression pattern and the cell lines were analyzed for sensitivity to PKC inhibition. All cell lines [IMR-32, LAN-2, LAN-5, SH-SY5Y and SK-N-BE(2)] expressed alpha, betaII, delta and epsilon isoforms of PKC, while no PKCeta or theta protein was detected in any cell line. PKCgamma was found only in LAN-2 cells. PKCalpha, betaII and delta were detected in 5 neuroblastoma tumors and PKCepsilon in 4 out of 5 tumors. Exposure to the PKC inhibitors GF109203X, Gö 6976 or Gö 6983 caused a decrease whereas activation of PKC with 12-O-tetradecanoyl phorbol 13-acetate caused an increase in the number of neuroblastoma cells. The effect of Gö 6976 was due to both inhibited proliferation and to increased apoptosis. While GF109203X suppressed neurite outgrowth induced by a growth factor combination, Gö 6976 potentiated neurite outgrowth. Our data suggest a role for classical PKC isoforms in neuroblastoma growth and survival and for novel isoforms in neurite outgrowth.

Multicomponent Polyanions. 53. Structure of Tetrakis(trimethylammonium) Tetra-μ-oxo-bis(triaquahexadecaoxo(trioxophenylphosphato)hexamolybdate) Dihydrate, [NH(CH3)3]4[{(C6H5P)Mo6O21(H2O)3}2].2H2O

The title compound crystallized in the monoclinic space group P21/n (No. 14) [a = 11.211 (5), b = 12.862 (3), c = 23.05 (1) Å, β = 94.37 (3)°, V = 3314 (2) Å3, Z = 2]. The polyanion can be regarded as a dimer of a phenylphosphonatohexamolybdate, (C6H5P)Mo6O23(H2O)3, linked by four O atoms. In this monomeric unit the six molybdenum octahedra are grouped into two parts consisting of four and two edge-sharing octahedra, respectively. These two parts are connected by two corner-sharing O atoms to form a bent Mo6 ring. The phenylphosphonate group coordinates to the Mo6 ring from the narrow side as a tripodal ligand. The {(C6H5P)Mo6O21(H2O)3}2 units form layers parallel to (001) and the structure is stabilized by hydrogen bonds between water and neighboring anions. The monomeric unit has been shown to be a key structure in the process of deducing the aqueous solution structures of the (C6H5P)Mo_6^{2-} and (C6H5P)Mo_7^{4-} species found in a previous equilibrium study of the H+–MoO_4^{2-}–(C6H5P)O_3^{2-} system.

A multicentre comparative evaluation of catheter valves

Catheter valves are an alternative to leg bags for urine drainage, but no studies have yet been published which have compared the performance of different valves. This study was undertaken to evaluate the performance of the seven catheter valves available on the UK market in April 1996. The study was carried out by the Continence Products Evaluation (CPE) Network funded by the Medical Devices Agency (Department of Health). Each valve type was tested for 1 week by 19-36 cognitively unimpaired and manually dextrous subjects recruited from 11 test centres. At the end of each week, subjects completed an evaluation form (based on a three-point rating scale) to record product performance. The same catheter valves were also tested for ease of opening/closing by 33 subjects (mostly catheter users) who had some manual impairment. Performance scores varied widely between products. It was found that, to be successful, a valve needs to be easy to manipulate, leak-free, comfortable and inconspicuous. Prescribers need to be aware of the strengths and limitations of different valves for appropriate product selection.

Speciation in Vanadium Bioinorganic Systems. 2. An NMR, ESR, and Potentiometric Study of the Aqueous H(+)-Vanadate-Maltol System

A systematic study of the physiologically interesting vanadium-maltol (V-MaH) system has been performed in 0.150 M Na(Cl) at 25 degrees C, using NMR, ESR, and potentiometric techniques. Complexation occurs within a wide pH range, from around 1 up to 10.5. However, a pH-, concentration-, and time-dependent spontaneous reduction of vanadium(V) to vanadium(IV) occurs. From ESR spectra the conditions for this reduction are evaluated and discussed. From potentiometric (glass electrode) and quantitative (51)V NMR measurements, the full speciation in the H(+)-H(2)VO(4)(-)-MaH system was determined in the pH range 5-10.5. Data were evaluated with the computer program LAKE, which is able to treat combined emf and NMR data. The pK(a) value for MaH was determined to be 8.437 +/- 0.005. In the ternary system, three complexes are formed: VMa(2)(-), VMa(-), and VMa(2)(-), having log beta(0,1,2) = 7.02 +/- 0.03, log beta(0,1,1) = 2.66 +/- 0.05, and log beta(-)(1,1,1) = -7.37 +/- 0.21. The errors given are 3sigma. The VMa(2)(-) complex appears as the main species in a pH range from 4.5 to 8.5, whereas both mononuclear monoligand species are minor. Equilibrium conditions are illustrated in distribution diagrams, and the structures of the complexes formed are proposed.

Alzheimer amyloid beta-peptides exhibit ionophore-like properties in human erythrocytes

There is growing evidence that the amyloid beta-peptide (beta 1-40) is involved in the aetiology of Alzheimer's disease also implicating an altered calcium homeostasis of affected cells. Beta 1-40 has been proposed to form calcium channels in synthetic bilayer membranes [1]. We wanted to investigate in the present study whether beta 1-40 (or fragments thereof) could act as ionophores in a biological membrane like the one in human erythrocytes. Incubation of the cells for 2 h and 4 h at 37 degrees C together with 6 mumol L-1 of beta 1-40 or of fragments beta 1-28 and beta 25-35, resulted in a significantly decreased energy charge qualitatively similar to the one obtained by a known calcium ionophore (A 23187, 0.05 mumol L-1). Moreover, beta 1-40 and its two fragments induced a significant alteration of 45Ca permeability in human red blood cells of the same type as the one achieved by the calcium ionophore. The ionophoric action of beta 1-40 and its two fragments may lead to an increase of the intracellular calcium ion concentration, in turn resulting in enhanced Ca(2+)-ATPase activity and a decrease in energy charge. This may be valid also for neuronal plasma membranes and could, therefore, be a possible aetiological mechanism in Alzheimer's disease.

Competitive elution of protein A fusion proteins allows specific recovery under mild conditions

A novel system is described for mild elution of fusion proteins by competitive elution. The approach is based on displacement of immobilized fusions containing a monovalent IgG-binding staphylococcal protein A fragment (Z) from an IgG-affinity matrix by a divalent fragment fused to a serum-albumin-binding region derived from streptococcal protein G. Using real-time interaction analysis, the binding (K(aff)) to polyclonal human IgG was found to be 3.3 (+/- 0.4) x 10(8) M-1 for divalent ZZ and 2.0 (+/- 0.1) x 10(7) M-1 for monovalent Z. This more than tenfold difference in binding strength ensures a high efficiency in the elution step. The competitor protein can specifically be removed and recovered from the elution mixture by subsequent passage through a human serum albumin(HSA)-affinity column, leaving only the target fusion protein in the flow-through fraction. Here, we show that a recombinant Klenow fragment of DNA polymerase I expressed in Escherichia coli can be recovered with high yield, and retained activity, from a crude bacterial lysate by IgG-affinity chromatography using mild conditions during both binding and elution.

Direct effect of insulin on 45calcium uptake in human erythrocytes

OBJECTIVE

High blood pressure is prevalent in obesity and non-insulin dependent diabetes mellitus; both conditions, with insulin resistance and essential hypertension, have been associated with increasing intra-erythrocytic levels of calcium ions. We tested the hypothesis of whether insulin itself might be responsible for the abnormal red cell cytosolic free calcium.

DESIGN

The ionic effects of insulin were studied on the kinetics of 45calcium uptake in vitro in normal human erythrocytes.

SETTING

The study was performed in the outpatient clinic of a central hospital.

SUBJECTS

Sixteen healthy, normotensive individuals with normal body mass index were recruited for the study.

MAIN OUTCOME MEASURES

Blood from eight individuals was used for time-dependent studies of 45calcium uptake in erythrocytes and blood from another eight individuals was used for dose-dependent studies of insulin effect.

RESULTS

The rate of 45calcium influx in red blood cells has two components, a fast component (0-10 min), which measures the initial rate of 45calcium influx, and a slow component (10-60 min) probably reflecting a relatively large backflux of calcium (calcium efflux), which accordingly determines an apparent low rate of 45calcium influx between 10-60 min. The uptake was linear with time between 10-120 min regardless of insulin being present or not. Insulin at a concentration of 120 mU L-1 significantly decreased the 45calcium uptake in a time-dependent fashion between 10-120 min. The uptake was 508 (+/- 59) at 60 min in the presence of insulin vs. a control value of 529 (+/- 59) pmol mL red blood cells-1 (P < 0.001). The corresponding figures at 120 min were 742 (+/- 109) and 767 (+/- 127), respectively (P = 0.02). Inconsistent results were obtained on 45calcium uptake at 60 min by varying insulin concentrations from 40-640 mU L-1 and a dual effect of insulin on 45calcium uptake could not be excluded, one at a fairly low concentration of insulin (40-120 mU L-1) and another at a high concentration (160-640 mU L-1).

CONCLUSION

The data indicate a direct role of insulin in the transport process of calcium into normal human erythrocytes.

Reversed-phase high-performance liquid chromatographic determination of 7 alpha-hydroxy-4-cholesten-3-one in human serum

A method for the determination of 7 alpha-hydroxy-4-cholesten-3-one in human serum has been developed. The method is based upon solid-phase (C18) extraction of serum after addition of 7-beta-hydroxy-4-cholesten-3-one as internal standard. The extract is analysed by reversed-phase HPLC using acetonitrile-water as a mobile phase. The effluent is monitored at 241 nm. The overall recoveries of the method range from 96% to 105%. The coefficient of variation for the within-run precision is 3.2% (n = 20, mean = 13.0 ng/ml) and for the between-run precision 3.8% (n = 32, mean = 13.3 ng/ml). The limit of detection is 3 ng at a signal-to-noise ratio of 3:1, which corresponds to 1 ng/ml using 3 ml of serum. The median value of 7 alpha-hydroxy-4-cholesten-3-one found in blood donors (n = 27) was 8.9 ng/ml (range 2-35 ng/ml).