Effect of hydroxyeicosatetraenoic acids on furosemide-sensitive chloride secretion in rat distal colon

Arachidonic acid metabolites such as prostaglandins, thromboxanes, and leukotrienes are well known modulators of intestinal vascular perfusion, motility, and electrogenic ion transport. We investigated the effect of different hydroxyeicosatetraenoic acids (HETEs) from cytochrome P450- and lipoxygenase-dependent arachidonate metabolism on electrogenic chloride secretion in rat distal colon. Using conventional Ussing techniques, basolateral 12-HETE significantly decreased basal short-circuit current (I(sc)) and inhibited furosemide-sensitive Cl(-) secretion stimulated by either dibutyryl cAMP, prostaglandin E(2), or theophylline in a concentration-dependent manner (IC(50) = 1.5 nM). These data were underlined by significant inhibition of J(net)(Cl) in unidirectional (36)Cl flux measurements. Direct regulation of the basolateral Na(+)-K(+)-2Cl(-) cotransporter or the Na-K-ATPase could be excluded because 12-HETE had no effect on furosemide-sensitive K(+) secretion induced by epinephrine, or ouabain-sensitive Na(+) reabsorption stimulated by aldosterone. Inhibitors of Ca(2+)-activated and voltage-gated K(+) channels such as apamin, charybdotoxin, and dendrotoxin did not affect secretagogue-dependent I(sc) and its regulation by 12-HETE. In contrast, glibenclamide significantly attenuated the effect of 12-HETE on secretagogue-induced I(sc), whereas chromanol 293B, an inhibitor of cAMP-dependent K(+) conductance, had an additive effect. We speculate that 12-HETE, like glibenclamide, affects intestinal Cl(-) secretion by inhibiting basolateral K(+)(ATP) channels. In contrast to these findings, neither 5-HETE nor 20-HETE had any effect on basal I(sc) or cAMP-dependent Cl(-) secretion.

Primary cell cultures of bovine colon epithelium: isolation and cell culture of colonocytes

Epithelial cells from bovine colon were isolated by mechanical preparation combined with an enzymatic digestion from colon specimens derived from freshly slaughtered animals. After digestion with collagenase I, the isolated tissue was centrifuged on a 2% D-sorbitol gradient to separate epithelial crypts which were seeded in collagen I-coated culture flasks. By using colon crypts and omitting the seeding of single cells a contamination by fibroblasts was prevented. The cells proliferated under the chosen culture conditions and formed monolayer cultures which were maintained for several weeks, including subcultivation steps. A population doubling time of about 21 hr was estimated in the log phase of the corresponding growth curve. During the culture period the cells were characterized morphologically and enzymatically. By using antibodies against cytokeratine 7 and 13 the isolated cells were identified as cells of epithelial origin. Antibodies against vimentin served as negative control. Morphological features such as microvilli, desmosomes and tight junctions, which demonstrated the ability of the cultured cells to restore an epithelial like monolayer, were shown by ultrastructural investigations. The preservation of the secretory function of the cultured cells was demonstrated by mucine cytochemistry with alcian blue staining. A stable expression of enzyme activities over a period of 6 days in culture occurred for gamma-glutamyltranspeptidase, acid phosphatase and NADH-dehydrogenase activity under the chosen culture conditions. Activity of alkaline phosphatase decreased to about 50% of basal value after 6 days in culture. Preliminary estimations of the metabolic competence of these cells revealed cytochrome P450 1A1-associated EROD activity in freshly isolated cells which was stable over 5 days in cultured cells. Then activity decreased completely. This culture system with primary epithelial cells from the colon will be used further as a model for the colon epithelium in toxicological studies in vitro.

[Efficacy of and tolerance to prolonged release prazosin in patients with hypertension and non-insulin dependent diabetes]

The treatment of hypertension represents one of the major elements of the cardiovascular prognosis in type II diabetes. Among antihypertensive drugs, alpha blockers may be interesting because of the absence of unfavourable effects on plasma glucose and lipid levels.

OBJECTIVE

The aim of this study was to evaluate the effectiveness and the safety of prazosin osmotic tablet treatment in non-insulin-dependent diabetic patients with mild to moderate arterial hypertension.

METHODS

After an initial 4-week-single-blind placebo period, 81 hypertensive subjects (162 +/- 11/96 +/- 5 mmHg) with type II diabetes were included in the study to receive prazosin osmotic tablet (o.t) open-label therapy at the dose of 2.5 mg/day for 12 weeks. After 4 weeks of treatment the dosage of prazosin o.t was increased to 5 mg/day if the diastolic blood pressure remained > or = 90 mmHg.

RESULTS

Both supine and standing systolic and diastolic blood pressures were significantly decreased (P < 0.001) with prazosin therapy from 162 +/- 10/96 +/- 5 mmHg in supine and 160 +/- 12/95 +/- 6 mmHg in the upright position, to 149 +/- 15/86 +/- 9 mmHg and 148 +/- 16/86 +/- 9 mmHg respectively at the end of the 12-week-treatment period. There were no significant changes in the glycemic parameters (glycemia, haemoglobin A1c) during the prazosin therapy compared with baseline values. A significant decrease of triglycerides (P = 0.005), total cholesterol (P < 0.001) and LDL cholesterol (P = 0.03) levels was observed during prazosin therapy compared with the baseline measurements, whereas HDL cholesterol remained stable. Only 6% of the patients reported adverse events in relation with the study drug during the active treatment period.

CONCLUSION

This study showed a significant decrease of the blood pressure in hypertensive subjects with type II diabetes after prazosin o.t treatment, without any change of glycemic parameters. Moreover, there was a favourable evolution of the lipidic parameters during the study characterised by a significant decrease of triglycerides and total and LDL cholesterol.

DIAS I: duplex-sonographic assessment of the cerebrovascular status in acute stroke. A useful tool for future stroke trials

BACKGROUND AND PURPOSE

A number of controlled trials have evaluated the benefit of intravenous thrombolysis in acute stroke with inconsistent results. None of these studies assessed the initial vascular status or provided information regarding the recanalization rate after therapy. Further trials need to clarify whether certain subgroups might possibly benefit more than others from intravenous thrombolysis. Therefore, a fast and valid method for assessment of cerebrovascular status is needed. In this multicenter study, we evaluated the potentials and limitations of color-coded duplex sonography (TCCS) for cerebrovascular status assessment in acute stroke patients before and after therapy. Furthermore, we compared the recanalization rate for patients referred to thrombolytic and conservative medical therapy.

METHODS

Fifty-eight patients suffering from hemispheric stroke were enrolled consecutively in 8 centers. Duplex sonography was performed on admission, 2 hours after start of therapy, and 24 hours after onset of symptoms. Therapy was started within 6 hours.

RESULTS

Intravenous thrombolysis was performed in 18 patients, conservative medical therapy in 39 patients, and early thromboendarterectomy in 1 patient. The middle cerebral artery (MCA) mainstem was patent in 29 patients (53.7%), occluded in 25 (46.3%), and was not assessable in 4 patients. Recanalization of the occluded MCA after 2 and 24 hours was diagnosed in 50% and 78% of the patients treated with rtPA and in 0% and 8% in the conservatively treated patients.

CONCLUSIONS

Intravenous thrombolysis is highly effective in restoring blood flow after MCA occlusion. TCCS is suitable for assessment of the cerebrovascular status in acute stroke and therefore might define therapeutically relevant subgroups of patients in future stroke trials on the basis of their vascular pathology.

Topical acetyl salicylate and dipyrone attenuate neurogenic protein extravasation in rat skin in vivo

The effect of topically applied acetyl salicylic acid (ASA) and dipyrone on capsaicin-evoked protein extravasation was investigated by dermal microdialysis in rat. After a baseline of 75 min, capsaicin (1%) was applied epicutaneously under occlusion for 75 min above the capillaries. Topical capsaicin stimulation induced neurogenic protein extravasation with a mean increase of protein concentration in the perfusate of 165+/-27% (mean+/-SEM; n=15), whereas in sham-stimulated sites protein concentration decreased to 73+/-7% of the prestimulation value (n=6). ASA (2-200 mg/ml) and dipyrone (3-300 mg/ml) dose-dependently reduced the capsaicin induced protein extravasation to 118+/-23% (ASA, 200 mg/ml; n=8) and 72+/-9% (dipyrone, 300 mg/ml; n=8) of the prestimulation value. ASA and dipyrone antagonized the excitatory effects of capsaicin on skin nociceptors and thus suppressed the neurogenic protein extravasation.

Stochastic resonance in two-dimensional arrays of coupled nonlinear oscillators

In this Brief Report we report the results of computer simulations on the periodic and noise driving of two-dimensional square arrays of coupled nonlinear oscillators. We find significant improvement in the output of these arrays over their one-dimensional counterparts (quantified by signal-to-noise ratio in the power spectrum at the frequency of the periodic driving). We also find that, within the limited resolution of our simulations, the one-dimensional scaling laws proposed by Lindner et al. [Phys. Rev. E 53, 2081 (1996)] seem to hold quite well for two-dimensional arrays.

[Cardiac side effects of anti-HIV agents]

Both nature and prognosis of cardiac complications occurring in patients infected by the Human Immunodeficiency Virus-1 (HIV-1) have changed considerably since the introduction of highly acive and anti-retroviral triple therapy ("HART"). Opportunist cardiac infections have thus been displaced and side effects of drugs now occupy the primary aetiological role. Torsades de pointe may be exceptionally triggered by anti-infectious agents such as pentacarinat or trimethoprime-sulfamethoxazole, as are those induced by the association of ketoconazole and terfenadine or cisapride, the dangers of which are well known and the prevention more effective, especially with the association with HIV antiproteases which inhibit the cytochrome P450. The diagnosis of iatrogenic myocardial dysfunction is more difficult, except when it occurs acutely as with phosphonoformate (Foscarnet), or interleukine-2. Progressive cardiomyopathy caused by -interferon and dideoxynucleosides (zidovudine, didanosine and zalcitabine), reversible on withdrawal of the drug responsible in half the cases, should be distinguished from those due to the HIV itself (therapeutic relay) or to another associated cause (alcohol, coronary artery disease). The coronary complications of diseases treated by antiproteases usually occur in smokers whose cholesterol and triglyceride levels are rapidly increased with HAART. In a series of 9 patients (amongst 700 treated with the antiproteases), after the acute phase of myocardial infarction during which the interventional approach is often preferred, the medium-term prognosis is relatively good, on condition that the patients correct the hyperlipidaemia and give up smoking.

Sleep apnea and quality of life

OBJECTIVE

To investigate the effects of sleep apnea (SA) on the quality of life (QOL).

DESIGN

A prospective study of QOL in patients with and without SA as defined by an apnea-hypopnea index (AHI) >5.

SETTING

University-based outpatient clinics.

PATIENTS

Primary care patients followed in a general internal medicine clinic as well as those referred to a sleep disorders clinic at the University of Wisconsin Hospital and Clinics were consecutively recruited and classified into 3 groups of subjects: (1) patients without SA (AHI<5) (n=46), (2) patients with mild SA (AHI 5-15) (n=16), and (3) patients with moderate to severe SA (AHI>15) (n=21).

INTERVENTIONS

NA.

MEASUREMENTS

QOL was assessed with the Medical Outcomes Study SF-36 Health Survey. Health history and demographic data were obtained via structured interview and medical record review. All subjects underwent overnight polysomnography for diagnosis of SA.

RESULTS

After controlling for age, gender, body mass index, and number of comorbid conditions, the association between sleep apnea and QOL was significant in the domains of physical functioning and role limitation due to physical health problems (p<0.05) and was borderline in vitality (p<0.1). Patients with both mild and moderately severe SA scored significantly lower (worse) than did patients without SA in physical functioning and in role limitations due to physical-health (82 and 83 vs. 92, respectively). Moderate to severe SA subjects scored significantly lower in vitality than did subjects without SA (51 vs. 64, p<0.05). Subscales analysis revealed that subjects with moderate to severe SA had significantly lower scores that did those without SA in positive affect (69 vs. 79), current health perceptions (71 vs. 80) and vitality (50 vs. 70), p<0.05 for all comparisons. A large percentage of patients without SA had perfect scores of 100 (ceiling effect) on the physical, social, and role functioning scales.

CONCLUSIONS

SA has an independent impact on several QOL domains after adjusting for differences in age, gender, body mass index, and comorbidity. QOL outcomes were likely attenuated by ceiling effects. Disentangling the scales that measure multidimensional QOL (positive and negative aspects) enhanced the ability of the SF-36 to detect important consequences of sleep apnea on QOL.

Familial hypomagnesaemia with hypercalciuria and nephrocalcinosis maps to chromosome 3q27 and is associated with mutations in the PCLN-1 gene

Familial hypomagnesaemia with hypercalciuria and nephrocalcinosis (FHHNC, MIM 248250) is a complex renal tubular disorder characterised by hypomagnesaemia, hypercalciuria, advanced nephrocalcinosis, hyposthenuria and progressive renal failure. The mode of inheritance is autosomal recessive. A primary defect in the reabsorption of magnesium in the medullary thick ascending limb of the loop of Henle (mTAL) has been proposed to be essential in FHHNC pathophysiology. To identify the underlying genetic defect we performed linkage analysis in eight families, including three with consanguineous marriages. We found linkage to microsatellite markers on chromosome 3q27 with a maximum two-point lod score (Zmax) of 5.208 for D3S3530 without evidence for genetic heterogeneity. Haplotype analysis revealed crucial recombination events reducing the critical interval to 6.6cM. Recently, mutations in the gene PCLN-1, mapping to 3q27 and coding for paracellin-1, were identified by Simon et al (1999) as the underlying genetic defect in FHHNC. Paracellin-1 represents a renal tight junction protein predominantly expressed in the TAL. Mutational analysis in our patient cohort revealed eight different mutations in the PCLN-1 gene, within six novel mutations. In seven of 13 mutant alleles we detected a Leu151 substitution without evidence for a founder effect. Leu151 is a residue of the first extracellular loop of paracellin-1, the part of the protein expected to bridge the intercellular space and to be important for paracellular conductance. This study confirms the implication of paracellin-1 defects in FHHNC and points to a predominant role of this protein in the paracellular reabsorption of divalent cations in the TAL.

Mycophenolate mofetil decreases endothelial prostaglandin E2 in response to allogeneic T cells or cytokines

BACKGROUND

Prostaglandin E2 (PGE2) is a powerful endogenous immune suppressant and interferes with various T-cell functions. However, it is not known in detail whether immunosuppressive drugs influence the PGE2-driven immune response in transplant patients. Therefore, we investigated the effect of several immunosuppressive compounds, in particular the novel drug mycophenolate mofetil (MMF), on endothelial PGE2 release.

METHODS

Endothelial cells (HUVEC) were activated by either allogeneic CD4+ or CD8+ T cells, or by the cytokines interleukin-1 or gamma-interferon. Using an enzyme-linked immunosorbent assay, we analyzed PGE2 release of the activated HWEC in the presence of MMF, cyclosporine, or tacrolimus. As verapamil and mibefradil also possess immunosuppressive properties, they were included in the study as well.

RESULTS

Activation of HUVEC with interleukin-1 or T cells resulted in a drastic accumulation of PGE2 in the supernatant. Cyclosporine or tacrolimus had no effect on PGE2 release. However, Ca2+ channel blockers, when applied at higher dosages, caused a significant increase in PGE2. Interestingly, MMF strongly diminished the PGE2 level in the cell culture supernatant in a concentration-dependent manner.

CONCLUSION

The results demonstrate an inhibitory effect of MMF on PGE2 production, which may lower the benefits of the PGE2-triggered immune response after organ transplantation.

Prostaglandin deficiency promotes sensitization of adenylyl cyclase

Inhibition of prostaglandin synthesis by the drug indomethacin suppresses the synthesis of the cyclic AMP antagonist, prostaglandylinositol cyclic phosphate (cyclic PIP), and leads to a metabolic state comparable to type II diabetes. It was of interest whether prostaglandin-deficiency likewise causes sensitization of adenylyl cyclase, as this has been reported for the diabetic state. In liver plasma membranes of indomethacin-treated male rats, basal and forskolin-stimulated cyclic AMP synthesis remained unchanged when compared to untreated control rats. In control rats, stimulation of cyclic AMP synthesis by fluoride (2.2-fold) or glucagon (3.5-fold) was much lower than stimulation by forskolin (6.6-fold). In contrast, in indomethacin-treated rats, stimulation of cAMP synthesis by fluoride (4.6-fold) or glucagon (5.2-fold) nearly matched the stimulation by forskolin (6.4-fold). The level of alpha1-adrenergic receptors was slightly reduced, from 450 to 320 fmol/mg protein, by the indomethacin treatment. Independent of the treatment by indomethacin, stimulation of cyclic AMP synthesis by adrenaline failed, in agreement with the low density of adrenergic beta-receptors. In conclusion, PGE deficiency sensitizes adenylyl cyclase in rat liver for G protein-coupled receptors (glucagon) and also for fluoride.

Phytochemical investigation of Aglaia rubiginosa

The phytochemical investigation of a methanolic leaf extract of Aglaia rubiginosa furnished 15 isoprenoid constituents, eight of which represented new natural entities. Two androstane derivatives (1 and 2), previously synthesized, and also obtained by microbiological transformations; an extraordinary 17-octanor-cycloartane-ring-A-seco acid (3); four cycloartane-type triterpenes (4-7); and three unusual cholesterol derivatives (8-10) were isolated, along with two known dammaranes (11 and 12), a stigmastandiol (13), and beta-sitosterol and its beta-D-glucoside. Spectroscopic structure elucidation of the new natural products (1-3, 6, 7, 8-10) is described.

Molecular cloning of the CRM1 gene from Candida albicans

In a screen for Candida albicans genes capable of supressing a ste20Delta mutation in Saccharomyces cerevisiae, a homologue of the exportin-encoding gene CRM1 was isolated. The CaCRM1 gene codes for a protein of 1079 amino acids with a predicted molecular weight of 124 029 and isoelectric point of 5.04. Crm1p from C. albicans displays significant amino acid sequence homology with Crm1p from Saccharomyces cerevisiae (65% identity, 74% similarity), Schizosaccharomyces pombe (55% identity, 66% similarity), Caenorhabditis elegans (45% identity, 57% similarity), and Homo sapiens (48% identity, 59% similarity). Interestingly, CaCRM1 encodes a threonine rather than a cysteine at position 533 in the conserved central region, suggesting that CaCrm1p is leptomycin B-insensitive, like S. cerevisiae Crm1p. CaCRM1 on a high copy vector can complement a thermosensitive allele of CRM1 (xpo1-1) in S. cerevisiae, showing that CaCrm1p and S. cerevisiae Crm1p are functionally conserved. Southern blot analysis suggests that CaCRM1 is present at a single locus within the C. albicans genome. The nucleotide sequence of the CaCRM1 gene has been deposited at GenBank under Accession No. AF178855.

Benefit of echocontrast-enhanced transcranial color-coded duplex ultrasound in the assessment of intracranial collateral pathways

BACKGROUND AND PURPOSE

Although clinically important, proper assessment of intracranial arterial collateral pathways by transcranial color-coded duplex sonography (TCCD) in patients with internal carotid artery (ICA) high-grade stenosis or occlusion is occasionally made difficult by an insufficient temporal bone window, an unfavorable insonation angle, or low flow velocity or volume. In these cases, echocontrast could be helpful to increase the diagnostic confidence or to make the diagnosis at all.

METHODS

We investigated 50 temporal windows of 44 patients with ipsilateral high-grade (>/=70%) ICA stenosis or occlusion and insufficient native transtemporal insonation conditions before and after the application of the echo enhancer Levovist with an infusion pump.

RESULTS

Compared with the precontrast scans, echocontrast allowed for more segments to be evaluated by pulsed Doppler sonography (P<0. 0001) and for longer lumen segments to be displayed on color mode (P<0.0001). Also, collateral flow via the anterior and posterior communicating artery could be demonstrated in 25 and 32 scans, respectively, compared with only 1 demonstration of each collateral pathway before the application of contrast medium (both P<0.0001). Similarly, with the help of contrast medium, flow velocity in the middle cerebral artery could be measured in 45 cases compared with only 26 cases before contrast was applied (P<0.0001).

CONCLUSIONS

In patients with poor precontrast visualization of intracranial arteries, echocontrast-enhanced TCCD is very helpful in the assessment of intracranial collateral pathways recruited downstream to ICA stenoses and occlusions.

Impact of silver and copper on the survival of amoebae and ciliated protozoa in vitro

The efficacy of 1:10 silver/copper combinations for inactivation of Hartmannella vermiformis amoebas and the ciliated protozoan Tetrahymena pyriformis in vitro was studied. Tetrahymena and Hartmannella/isolate 19 were inactivated for 2 log steps by 100 + 1000 micrograms/l Ag + Cu. Hartmannella/isolate 21 was more resistant. 500 + 5000 micrograms/l produced only a 0.6 log reduction. The investigations clearly showed that levels within the limit of the German drinking water regulation (10 + 100 micrograms/l Ag + Cu) could not inactivate these protozoas in vitro.

In vitro analysis of verapamil-induced immunosuppression: potent inhibition of T cell motility and lymphocytic transmigration through allogeneic endothelial cells

BACKGROUND

Cyclosporine A (CsA) and tacrolimus prevent proliferation but not transendothelial migration of alloreactive lymphocytes into donor organs. As a result, serious adverse effects, such as nephrotoxicity and neurotoxicity, have been observed under CsA/tacrolimus therapy. The incorporation of new drugs with infiltration blocking properties might enhance the efficacy of the current immunosuppressive protocol, allowing lower CsA/tacrolimus dosage. Because Ca2+ plays a critical role in cell-cell interaction, the Ca2+-channel blocker verapamil might be a good cany. didate for supporting CsA/tacrolimus-based therapy.

METHODS

A T-cell endothelial cell coculture model or immobilized immunoglobulin G globulin chimeras were employed to investigate how S- and R- verapamil interfere with the lymphocytic infiltration process. The expression and arrangement of membranous adhesion receptors and cytoskeletal F-actin filaments were analyzed by fluorometric method in the presence of. verapamil.

RESULTS

Both verapamil enantiomers strongly inhibited lymphocyte infiltration. CD4+ and CD8+ T-cells were influenced to a similar extent with regard to horizontal locomotion (CD4+=CD8+), but to a different extent with regard to adhesion and penetration (CD4+ > CD8+). Moreover, penetration was blocked to a higher extent than was adhesion. ID50-values were 31 microM (CD4+-adhesion) and 11 microM (CD4+-penetration). Verapamil reduced P-selectin expression on endothelial cells and effectively down-regulated binding of T-cells to immobilized P-selectin immunoglobulin G globulins (ID50=4.4 microM; CD4+). A verapamil-induced reduction of intracellular F-actin in T-lymphocytes was proven to be mainly responsible for diminished cell locomotion.

CONCLUSIONS

The prevention of CD4+ T-cell penetration by verapamil might argue for its use as an adjunct to CsA/tacrolimus-based immunosuppressive therapy.

Genotoxic potential of porphyrin type photosensitizers with particular emphasis on 5-aminolevulinic acid: implications for clinical photodynamic therapy

Photodynamic therapy (PDT) uses exogenously administered photosensitizers activated by light to induce cell death or modulation of immunological cascades, presumably via formation of reactive oxygen species (ROS). 5-Aminolevulinic acid (ALA) mediated photosensitization is increasingly used for the treatment of nonmelanoma skin cancer and other indications including benign skin disorders. Long-term side effects of this investigational modality are presently unknown. Just as tumor treatments such as ionizing radiation and chemotherapy can cause secondary tumor induction, PDT may potentially have a carcinogenic risk. Evaluation of the biological effects of ALA in absence of activating light and analysis of the mechanism of ALA-PDT and porphyrin-type photosensitizers mediated photosensitization indicate that this therapy has a pro-oxidant and genotoxic potential. However, porphyrin type molecules also possess antioxidant and antimutagenic properties. ALA-PDT delays photocarcinogenesis in mice, and topical ALA alone does not increase skin cancer incidence in these animals. Patients with increased tissue levels of ALA have an increased incidence of internal carcinoma, however, it is not clear whether this relationship is casual or causal. There is no evidence indicating higher rates of skin cancer in patients with photosensitivity diseases due to presence of high protoporphyrin IX (PP) levels in skin. Overall, the presently available data indicate that the risk for secondary skin carcinoma after topical ALA-PDT seems to be low, but further studies must be carried out to evaluate the carcinogenic risk of ALA-PDT in conditions predisposed to skin cancer.

[Management of first transient chest pain]

Unstable angina is the first diagnosis to consider in a patient with transient chest pain; if managed in the setting of a coronary care unit, this condition leads to myocardial infarction in less than 5% of patients. Conversely half of acute myocardial infarctions have been heralded by unrecognised unstable anginal; thus a good proportion of the 120,000 infarctions occurring yearly in France could be avoided. Pre-hospital diagnosis is based on chest pain characterisation since physical examination and electrocardiogram are usually normal when the patient is pain free. The major concern being to avoid underdiagnosis, sensitivity is in this setting more important than specificity the patient should be hospitalised whenever a reasonable doubt exists.

Lesions in the nuo operon, encoding NADH dehydrogenase complex I, prevent PurF-independent thiamine synthesis and reduce flux through the oxidative pentose phosphate pathway in Salmonella enterica serovar typhimurium

In Salmonella enterica serovar Typhimurium, PurF-independent thiamine synthesis (or alternative pyrimidine biosynthesis) allows strains, under some growth conditions, to synthesize thiamine in the absence of the first step in the purine biosynthetic pathway. Mutations have been isolated in a number of loci that prevent this synthesis and thus result in an Apb(-) phenotype. Here we identify a new class of mutations that prevent PurF-independent thiamine synthesis and show that they are defective in the nuo genes, which encode the major, energy-generating NADH dehydrogenase of the cell. Data presented here indicated that a nuo mutant has reduced flux through the oxidative pentose phosphate pathway that may contribute to, but is not sufficient to cause, the observed thiamine requirement. We suggest that reduction of the oxidative pentose phosphate pathway capacity in a nuo mutant is an attempt to restore the ratio between reduced and oxidized pyridine nucleotide pools.

EPR, ENDOR, and TRIPLE resonance spectroscopy on the neutral flavin radical in Escherichia coli DNA photolyase

Ultraviolet radiation promotes the formation of a cyclobutane ring between adjacent pyrimidine residues on the same DNA strand to form a pyrimidine dimer. Such dimers may be restored to their monomeric forms through the action of a light-absorbing enzyme named DNA photolyase. The redox-active cofactor involved in the light-induced electron transfer reactions of DNA repair and enzyme photoactivation is a noncovalently bound FAD. In this paper, the FAD cofactor of Escherichia coli DNA photolyase was characterized as the neutral flavin semiquinone by EPR spectroscopy at 9.68 and 94.5 GHz. From the high-frequency/high-field EPR spectrum, the principal values of the axially symmetric g-matrix of FADH(*) were extracted. Both EPR spectra show an emerging hyperfine splitting of 0.85 mT that could be assigned to the isotropic hyperfine coupling constant (hfc) of the proton at N(5). To obtain more information about the electron spin density distribution ENDOR and TRIPLE resonance spectroscopies were applied. All major proton hfc's could be measured and unambiguously assigned to molecular positions at the isoalloxazin moiety of FAD. The isotropic hfc's of the protons at C(8alpha) and C(6) are among the smallest values reported for protein-bound neutral flavin semiquinones so far, suggesting a highly restricted delocalization of the unpaired electron spin on the isoalloxazin moiety. Two further hfc's have been detected and assigned to the inequivalent protons at C(1'). Some conclusions about the geometrical arrangement of the ribityl side chain with respect to the isoalloxazin ring could be drawn: Assuming tetrahedral angles at C(1') the dihedral angle between the C(1')-C(2') bond and the 2p(z)() orbital at N(10) has been estimated to be 170.4 degrees +/- 1 degrees.

[Clinical 12-month outcome with the foldable, hydrophobic acrylic lens AMO AR40NB]

BACKGROUND

More and more foldable acrylic lenses are implanted besides silicone and polymethylmethacrlyate (PMMA) lenses through small incision unfolding in the capsular bag. Complications were observed such as forceps marks, surface scratches and so called glistenings. Therefore, a profound clinical evaluation of a former by Ioptex marketed acrylic lens which has been readapted by Allergan also with regard to a special developed injector seemed to be necessary.

PATIENTS AND METHODS

Forty-four patients were enrolled within 14 days in a one-year, unilateral, non-comparative, open clinical study implanted with the AMO AR40NB hydrophobic acrylic IOL. This foldable acrylic IOL with biconvex optic design and extruded polymethylmethacrylate (PMMA) haptics (AR40) was implanted either using a folding forceps or the AMO AR40NB Insertion System through a temporal limbal hinged incision of 3.2 to 3.5 mm.

RESULTS

One-year postoperatively, 85% (28/33) best corrected distance visual acuity (BSCVA) of 0.5 (20/40) or better was reported, with 39% (13/33) reported BSCVA of 1.0 (20/20) or better. Those not achieving 0.5 or better suffered from either macular degeneration or other ophthalmic pathologies. There were no reports of surgical complications and ease of lens insertion was rated by the surgeon better than most in 98% of all cases. There were no persistent adverse events.

CONCLUSION

Results from this study of the AR40 demonstrate good clinical performance characteristics as well as better implantation with the injector Unfolder Sapphire.

Combination therapy with tirofiban and enoxaparin in acute coronary syndromes

BACKGROUND

Tirofiban, an intravenous glycoprotein IIb/IIIa antagonist, and enoxaparin, a low molecular weight heparin, have each been shown to be effective at reducing cardiac ischemic events compared to unfractionated heparin alone in separate trials of patients with unstable angina and non-Q-wave myocardial infarction. The combination of these agents may offer further therapeutic benefit.

MATERIALS AND METHODS

Fifty-five patients with non-Q-wave myocardial infarction were randomized to receive double-blind treatment with tirofiban (0.1 microgram/kg/min i.v.) for 48-108 h coadministered with either enoxaparin (1 mg/kg sc q 12 h) (n=26) or unfractionated heparin (i.v. adjusted to activated partial-thromboplastin time) (n=27) to evaluate pharmacokinetics, pharmacodynamics, and safety. The primary objective of the study was to investigate the effect of unfractionated heparin versus enoxaparin on the plasma clearance of tirofiban.

RESULTS

Coadministration of tirofiban and enoxaparin was generally well tolerated. Plasma clearance of tirofiban was 176.7+/-59.8 and 187.5+/-81.8 ml/min, respectively, for enoxaparin and unfractionated heparin-treated patients (P=NS). The mean difference was well within the prespecified criterion for comparability. Administration of tirofiban with enoxaparin vs. unfractionated heparin resulted in lesser variability and a trend towards greater inhibition of platelet aggregation using 5 microM adenosine phosphate agonist. More patients achieved target inhibition of platelet aggregation >70% in the tirofiban and enoxaparin group (84% vs. 65%, P=0.19). Median bleeding time was 21 min for tirofiban and enoxaparin vs. > or =30 min for tirofiban and unfractionated heparin (P=NS). For a given level of inhibition of platelet aggregation, bleeding time was less prolonged with tirofiban and enoxaparin than tirofiban and unfractionated heparin (adjusted mean bleeding time 19.6 vs. 24.9 min, P=0.02). Tirofiban plasma concentration and clearance were comparable whether coadministered with enoxaparin or unfractionated heparin. There were no major or minor bleeding events in either group by the TIMI criteria.

INTERPRETATION

The more consistent inhibition of platelet aggregation and lower adjusted bleeding time of tirofiban and enoxaparin vs. tirofiban and unfractionated heparin support the therapeutic potential of combining these two agents. These data from the first clinical report of coadministration of a glycoprotein IIb/IIIa receptor antagonist and a low molecular weight heparin are consistent with prior data which show differential pharmacodynamic effects of enoxaparin and unfractionated heparin on platelet aggregation.

[Treatment of stable angina. Coronary angioplasty versus medical treatment]

Stable angina is a common clinical condition in everyday practice. Several studies (ACME, MASS, RITA 2) compared the efficacy of angioplasty with medical management in this context with concordant results: significant reduction in the frequency of angina and improved exercise capacity, without reduction in the number of serious events (death, infarction). Even though developments in the field of angioplasty have provided better clinical results, especially with the use of stents, the indication of dilatation should be clearly defined by a series of clinical and angiographic parameters. Although resistance to well conducted medical treatment is an indication for revascularisation when possible, the indications should be reconsidered if persistent ischaemia with medical therapy has not been proved.