Prognostic value of motor evoked potential obtained by transcranial magnetic brain stimulation in motor function recovery in patients with acute ischemic stroke

BACKGROUND AND PURPOSE

The early prognostic application of transcranial magnetic brain stimulation (TMS) for assessing motor and functional recovery in ischemic stroke patients has yielded contradictory results. We performed a prospective study of patients with acute ischemic stroke and motor deficit to evaluate the early prognostic value of TMS in motor and functional recovery.

METHODS

Fifty patients with different degrees of hemiparesis were studied in the first week after ischemic stroke and evaluated by clinical scales (Medical Research Council Scale, Canadian Neurological Scale, Barthel Index), with clinical follow-up over 6 months. TMS (Magstim 200) was performed at the same time, recording the motor evoked potential (MEP) in the thenar eminence muscles, with facilitation by voluntary contraction.

RESULTS

Of the total group of 50 patients, MEP was absent in 20 and present in 30 (17 with normal and 13 with delayed central conduction time [CCT]). The patients with MEP showed better motor and functional recovery than those without. The MEP provided information on patient recovery, regardless of the initial strength and/or Barthel values. The degree of recovery was better in those patients with normal CCT than in those with delayed CCT.

CONCLUSIONS

MEP obtained by TMS in patients with hemiparesis after acute ischemic stroke is useful as an early prognostic indicator of motor and functional recovery. This technique would allow the early identification of those patients who will have a good recovery, particularly among those with severe initial paresis.

High frequency of altered HLA class I phenotypes in invasive colorectal carcinomas

We analyzed the expression of HLA class I antigens in 78 tumor tissue samples obtained from patients diagnosed as having colorectal carcinomas. A broad panel of mAbs defining HLA monomorphic, locus-specific and allele-specific determinants was used. In addition, an antibody defining HLA-C locus-specific determinant (L31) was also tested. Previous reports on these tumors indicated HLA class I losses of 30 to 40%. At least 73% of the patients in the present study had a detectable HLA class I alteration. These altered HLA phenotypes were classified as total HLA loss (18%) (phenotype I); HLA-A locus-specific loss (9%) (phenotype IIIa); HLA-B locus-specific loss (8%) (phenotype IIIb); HLA-A and B locus losses (2%) and HLA allelic losses (36%) (phenotype IV). We found no HLA-C locus losses. Autologous peripheral blood lymphocyte HLA class I typing was always necessary to define phenotype IV. We also studied the CD3 zeta chain in tumor tissues to correlate possible changes in the CD3 signal transduction pathway with HLA alterations. The CD3 ratio was frequently altered, but this alteration could not be correlated with tumor HLA phenotypes. The high frequency of HLA class I losses in colorectal carcinomas suggests that this finding is a widespread phenomenon and may be required to escape T-cell recognition. It remains to be determined whether HLA expression is "normal" in the rest of the 27% of our patients.

Cooperative stabilization of a molten globule apoflavodoxin fragment

We have destabilized apoflavodoxin by site-specific excision of its C-terminal helix. The resulting flavodoxin fragment (Fld1-149) is compact and monomeric at pH 7.0, with spectroscopic properties of a molten globule and a low conformational stability. To study if Fld1-149 is cooperatively stabilized, we have measured the equilibrium urea unfolding by fluorescence, circular dichroism, and size-exclusion chromatography. The three techniques produced coincident unfolding curves. Furthermore, the thermal unfolding seems also to be cooperative as the same temperature of half-denaturation is obtained using fluorescence and circular dichroism. Fld1-149 displays cold denaturation. The equilibrium properties of Fld1-149 demonstrate that molten globules lacking well-defined tertiary interactions can still be cooperatively stabilized and that cooperatively may appear in protein conformations of very low stability. This suggests that protein folding intermediates, can, in principle, be cooperatively stabilized.

The increased circulating prostate-specific antigen concentrations in women with hirsutism do not respond to acute changes in adrenal or ovarian function

Serum prostate-specific antigen (PSA) is produced in several female tissues and appears to be up-regulated by androgens. We have studied serum PSA concentrations in women with different forms of hyperandrogenism, focusing on the influence of changes in ovarian and adrenal function on these concentrations. Thirty-seven hirsute women were studied in the follicular phase of the menstrual cycle. Basal and ACTH-stimulated plasma samples were obtained, and sampling was repeated 1 (gonadal stimulation) and 21 (gonadal suppression) days after receiving a single im 3.75-mg dose of triptorelin. Eleven nonhyperandrogenic women served as controls. Hirsute women had increased PSA levels compared to controls. When considering the source of the hyperandrogenism, ovarian patients (those with increased serum androgen levels that normalized during gonadal suppression) and adrenal patients (those with increased androgen levels that remained elevated during gonadal suppression) presented increased PSA values, whereas hirsute patients without hyperandrogenemia had normal PSA levels. PSA levels did not change during ovarian or adrenal stimulation or during gonadal suppression with respect to initial values. Basal PSA levels showed significant correlations with basal total testosterone (r = 0.59; P < 0.001), free androgen index (r = 0.68; P < 0.001), sex hormone-binding globulin (r = -0.58; P < 0.001), dehydroepiandrosterone sulfate (r = 0.39; P < 0.01), 17-hydroxyprogesterone (r = 0.32; P < 0.05), and age (r = -0.33; P < 0.05) when patients and controls were considered as a whole. In conclusion, basal PSA levels are increased in hirsute patients and correlate with the degree of hyperandrogenism when patients and controls are considered as a whole. The adrenal and the ovary do not appear to be the source of PSA, suggesting that hyperandrogenism induces PSA secretion in tissues other than the adrenal and the ovary.

Intrahelical side chain interactions in alpha-helices: poor correlation between energetics and frequency

Polypeptide sequences in proteins may increase their tendency to adopt helical conformations in several ways. One is the recruiting of amino acid residues with high helical propensity. Another is the appropriate distribution of residues along the helix to establish stabilising side chain interactions. The first strategy is known to be followed by natural proteins because amino acids with high helical propensity are more frequent in alpha-helices. If proteins also followed the second strategy, stabilising amino acid pairs should be more frequent than others. To test this possibility we compared empirical energies of side chain interactions in alpha-helices with statistical energies calculated from a data base of proteins with low homology. We find some correlation between the stability afforded by the pairs and their relative abundance in alpha-helices but the realisation of energetic preferences into statistical preferences is very low. This indicates that natural alpha-helices do not regularly use intrahelical side chain interactions to increase their stability.

CD38 is functionally dependent on the TCR/CD3 complex in human T cells

One of the functions of surface CD38 is the induction of phosphorylation of discrete cytoplasmic substrates and mobilization of cytoplasmic calcium (Ca2+). The present work addresses the issue of whether the signaling mediated via CD38 operates through an independent pathway or, alternatively, is linked to the TCR/CD3 signaling machinery. We studied the signals elicited through CD38 by the specific agonistic IB4 monoclonal antibody (mAb) by monitoring the levels of cytoplasmic Ca2+ and the induced phenotypic and functional variations in T cell growth. IB4 mAb presented the unique ability to increase cytoplasmic Ca2+ levels, which correlated with the phosphorylation of the PLC-gamma1. These effects were blocked by phorbol 12-myristate 13-acetate (PMA) and were dependent on the presence of a functional TCR/CD3 surface complex, no effects being recorded on mutant Jurkat cells lacking part of the CD3 structures. CD38 signaling appeared to share with TCR/CD3 the ability to induce apoptotic cell death in Jurkat T cells, an event paralleled by specific up-regulation of the Fas molecule and inhibited by cyclosporin A. CD28, a costimulatory molecule, is synergized by increasing CD38-induced apoptotic cell death. The results indicate the existence of a strong functional interdependence between CD38 and TCR/CD3.

Differential stabilization of the three FMN redox forms by tyrosine 94 and tryptophan 57 in flavodoxin from Anabaena and its influence on the redox potentials

Flavodoxins are electron transfer proteins that carry a noncovalently bound flavin mononucleotide molecule as the redox-active center. The redox potentials of the flavin nucleotide are profoundly altered upon interaction with the protein. In Anabaena flavodoxin, as in many flavodoxins, the flavin is sandwiched between two aromatic residues (Trp57 and Tyr94) thought to be implicated in the alteration of the redox potentials. We have individually replaced these two residues by each of the other aromatic residues, by alanine and by leucine. For each mutant, we have determined the redox potentials and the binding energies of the oxidized FMN--apoflavodoxin complexes. From these data, the binding energies of the semireduced and reduced complexes have been calculated. Comparison of the binding energies of wild-type and mutant flavodoxins at the three redox states suggests that the interaction between Tyr94 and FMN stabilizes the apoflavodoxin--FMN complex in all redox states. The oxidized and semireduced complexes are, however, more strongly stabilized than the reduced complex, making the semiquinone/hydroquinone midpoint potential more negative in flavodoxin than in unbound FMN. Trp57 also stabilizes all redox forms of FMN, thus cooperating with Tyr94 in strong FMN binding. On the other hand, Trp57 seems to slightly destabilize the semireduced complex relative to the oxidized one. Finally, we have observed that reduction of mutants lacking Trp57 is slow relative to that of wild-type or mutants lacking Tyr94, which suggests that Trp57 could play a role in the kinetics of flavodoxin redox reactions.

Tyrosine phosphorylation of the CD3-epsilon subunit of the T cell antigen receptor mediates enhanced association with phosphatidylinositol 3-kinase in Jurkat T cells

T cell receptor signaling results both in T cell proliferation and apoptosis. A key enzyme at the intersection of these downstream pathways is phosphatidylinositol 3'-kinase (PI 3-kinase). In a previous report, we showed that the p85alpha subunit of the PI 3-kinase preferentially associated with the CD3-zeta membrane-proximal immunoreceptor tyrosine-based activation motif of the zeta chain (zetaA-ITAM) (Exley, M., Varticovski, L., Peter, M., Sancho, J., and Terhorst, C. (1994) J. Biol. Chem. 269, 15140-15146). Here, we demonstrate that tyrosine phosphorylation of CD3-epsilon can recruit the PI 3-kinase enzyme in a T cell activation-dependent manner. In vivo studies with Jurkat cells stably transfected with a CD8-CD3-epsilon chimera (termed CD8-epsilon) shows that ligation of endogenous CD3-epsilon or CD8-epsilon by specific antibodies induces tyrosine phosphorylation of CD3-epsilon or CD8-epsilon, respectively. Increased tyrosine phosphorylation correlates with increased binding of p85alpha PI 3-kinase and recruitment of PI 3-kinase enzymatic activity to CD3-epsilon or CD8-epsilon proteins. Mutagenesis studies in COS-7 cells, transiently transfected with CD8-epsilon, p85alpha, and Fyn cDNAs in various combinations, show that both Tyr170 and Tyr181 within the CD3-epsilon-ITAM are required for efficient binding of p85alpha PI 3-kinase. Thus, replacement of Tyr170 by Phe (Y170F), or Tyr181 by Phe (Y181F) significantly reduces binding of p85alpha PI 3-kinase, whereas it does not affect binding of Fyn. Further in vitro experiments suggest that a direct binding of the tandem SH2 domains of p85alpha PI 3-kinase to the two phosphorylated tyrosines in a single CD3-epsilon-ITAM may occur. The data also support a model in which a single CD3 subunit can recruit distinct effector molecules by means of TCR-mediated differential ITAM phosphorylation.

Mild adrenal and ovarian steroidogenic abnormalities in hirsute women without hyperandrogenemia: does idiopathic hirsutism exist?

To study ovarian and adrenal steroid profiles of women with idiopathic hirsutism, we compared sex steroid and basal and corticotropin (ACTH)-stimulated adrenal steroid levels before and after ovarian suppression induced by a long-acting gonadotropin-releasing hormone agonist analog (GnRH-a) in 24 hirsute women without hyperandrogenemia. Twelve healthy women served as controls for basal and ACTH-stimulated adrenal steroid levels. Serum levels of testosterone (T), sex hormone-binding globulin (SHBG), estradiol (E2), basal and ACTH-stimulated 17-hydroxyprogesterone (17OHP), dehydroepiandrosterone (DHEA), DHEA sulfate (DHEAS), delta 4-androstenedione (delta 4-A), 11-deoxycortisol (S) and cortisol (F), and basal and luteinizing hormone-releasing hormone (LHRH)-stimulated gonadotropin levels were measured before and 21 days after 3.75 mg intramuscular triptorelin in hirsute women. Basal T levels and basal and ACTH-stimulated delta 4-A, DHEA, and DHEAS levels were not different in hirsute women with respect to controls. Basal and ACTH-stimulated 17OHP was elevated, and decreased to normal after ovarian suppression with triptorelin. Although basal and ACTH-stimulated delta 4-A levels were normal, the delta delta 4-A/delta F and delta delta 4-A/delta 17OHP ratios were elevated and remained elevated after ovarian suppression, suggesting enhanced adrenal delta 4-17,20-lyase activity. T, F, S, and DHEAS levels were not affected by ovarian suppression. Basal and ACTH-stimulated 17OHP and delta 4-A, and stimulated DHEA concentrations were reduced with ovarian suppression, but their net increment and ratio to the increase of F in response to ACTH remained unchanged, reflecting the ovarian contribution to the secretion of these steroids. We conclude that idiopathic hirsute women with normoandrogenemia show an increase in ovarian secretion of 17OHP and a minimally increased adrenal delta 4-17, 20-lyase activity, suggesting that mild forms of ovarian and adrenal functional hyperandrogenism may be present in these patients with otherwise unexplained hirsutism.

CD38 ligation results in activation of the Raf-1/mitogen-activated protein kinase and the CD3-zeta/zeta-associated protein-70 signaling pathways in Jurkat T lymphocytes

CD38 ligation with the specific mAb IB4 induced early and late signaling events in Jurkat T cells, as judged by the transient induction of tyrosine phosphorylation of phospholipase C-gamma1, c-Cbl, zeta-associated protein (ZAP)-70, Shc, extracellular signal-regulated protein kinase-2 (Erk-2) as mitogen-activated protein (MAP) kinase, and increased expression of the activation Ag CD69. In addition, CD38 ligation induced Ras-dependent events such as Erk-2 mobility shift and increased Erk-2 kinase activity. Further evidence that Erk-2 activation is regulated by CD38 ligation was obtained indirectly with the observed induction of Raf-1, Lck, and Sos-1 mobility shifts, processes that are believed to be dependent, at least in part, on MAP kinase activation. Using a protein tyrosine kinase inhibitor, herbimycin A, or a protein kinase C inhibitor, Ro-31-8220, we found that the anti-CD38-induced Erk-2 activation is both protein tyrosine kinase and protein kinase C dependent. CD38 ligation also resulted in increased CD3-zeta tyrosine phosphorylation and its association with ZAP-70. CD38 ligation in a Jurkat Lck-deficient mutant, JCam1, failed to induce substrate tyrosine phosphorylation and activation of Erk-2. These data indicated that in Jurkat T cells, CD38 receptor triggering results in Lck-regulated activation of both Raf-1/MAP kinase and CD3-zeta/ZAP-70/phospholipase C-gamma1 signaling pathways.

CD38 ligation results in activation of the Raf-1/mitogen-activated protein kinase and the CD3-zeta/zeta-associated protein-70 signaling pathways in Jurkat T lymphocytes

CD38 ligation with the specific mAb IB4 induced early and late signaling events in Jurkat T cells, as judged by the transient induction of tyrosine phosphorylation of phospholipase C-gamma1, c-Cbl, zeta-associated protein (ZAP)-70, Shc, extracellular signal-regulated protein kinase-2 (Erk-2) as mitogen-activated protein (MAP) kinase, and increased expression of the activation Ag CD69. In addition, CD38 ligation induced Ras-dependent events such as Erk-2 mobility shift and increased Erk-2 kinase activity. Further evidence that Erk-2 activation is regulated by CD38 ligation was obtained indirectly with the observed induction of Raf-1, Lck, and Sos-1 mobility shifts, processes that are believed to be dependent, at least in part, on MAP kinase activation. Using a protein tyrosine kinase inhibitor, herbimycin A, or a protein kinase C inhibitor, Ro-31-8220, we found that the anti-CD38-induced Erk-2 activation is both protein tyrosine kinase and protein kinase C dependent. CD38 ligation also resulted in increased CD3-zeta tyrosine phosphorylation and its association with ZAP-70. CD38 ligation in a Jurkat Lck-deficient mutant, JCam1, failed to induce substrate tyrosine phosphorylation and activation of Erk-2. These data indicated that in Jurkat T cells, CD38 receptor triggering results in Lck-regulated activation of both Raf-1/MAP kinase and CD3-zeta/ZAP-70/phospholipase C-gamma1 signaling pathways.

An octamer element functions as a regulatory element in the differentiation-responsive CD11c integrin gene promoter: OCT-2 inducibility during myelomonocytic differentiation

The integrin CD11c/CD18 mediates leukocyte adhesion to endothelium and other cell types and is a receptor for LPS, iC3b, and fibrinogen. CD11c expression is restricted to myeloid and activated B cells, is regulated during leukocyte differentiation, and constitutes a diagnostic tool for hairy cell leukemia. Mapping of in vivo DNA-protein interactions in the CD11c proximal promoter revealed three adjacent myeloid-specific interactions, one of which lies on an octamer consensus sequence, ATTT GCAT (Oct185). Oct185 disruption increased the CD11c promoter activity while decreasing its myeloid differentiation responsiveness, indicating that Oct185 contributes to the activity of the CD11c promoter and suggesting that Oct185 is a negative regulatory element whose function changes during myeloid differentiation. Oct185 is recognized by the ubiquitous Oct-1 factor in all cell lineages and by Oct-2 in B lymphoid lineage cells. Unexpectedly, Oct-2 binding to Oct185 was induced de novo upon monocytic differentiation of U937 and HL-60 cells but not during HL-60 granulocytic differentiation, as determined by electrophoretic mobility shift assays and immunochemical studies, and Oct-2 complexes were also observed in cultured adherent monocytes. Western blotting showed that the pattern of Oct-2 isoforms in myeloid cells is similar to that seen in B cells. The Oct-2 up-regulated expression in differentiating myeloid cells and its binding to the Oct185 negative regulatory element suggests its involvement in the differentiation-regulated activity of the CD11c promoter and might represent an important parameter for the myeloid- and B cell-restricted expression of the CD11c/CD18 integrin and other molecules with similar patterns of expression.

An octamer element functions as a regulatory element in the differentiation-responsive CD11c integrin gene promoter: OCT-2 inducibility during myelomonocytic differentiation

The integrin CD11c/CD18 mediates leukocyte adhesion to endothelium and other cell types and is a receptor for LPS, iC3b, and fibrinogen. CD11c expression is restricted to myeloid and activated B cells, is regulated during leukocyte differentiation, and constitutes a diagnostic tool for hairy cell leukemia. Mapping of in vivo DNA-protein interactions in the CD11c proximal promoter revealed three adjacent myeloid-specific interactions, one of which lies on an octamer consensus sequence, ATTT GCAT (Oct185). Oct185 disruption increased the CD11c promoter activity while decreasing its myeloid differentiation responsiveness, indicating that Oct185 contributes to the activity of the CD11c promoter and suggesting that Oct185 is a negative regulatory element whose function changes during myeloid differentiation. Oct185 is recognized by the ubiquitous Oct-1 factor in all cell lineages and by Oct-2 in B lymphoid lineage cells. Unexpectedly, Oct-2 binding to Oct185 was induced de novo upon monocytic differentiation of U937 and HL-60 cells but not during HL-60 granulocytic differentiation, as determined by electrophoretic mobility shift assays and immunochemical studies, and Oct-2 complexes were also observed in cultured adherent monocytes. Western blotting showed that the pattern of Oct-2 isoforms in myeloid cells is similar to that seen in B cells. The Oct-2 up-regulated expression in differentiating myeloid cells and its binding to the Oct185 negative regulatory element suggests its involvement in the differentiation-regulated activity of the CD11c promoter and might represent an important parameter for the myeloid- and B cell-restricted expression of the CD11c/CD18 integrin and other molecules with similar patterns of expression.

Production of carpophores of Lentinus edodes and Ganoderma lucidum grown on cork residues

Cork, being widely used in industry, generates high amounts of waste of difficult elimination because of its complex biological degradation, and the high pollutant smokes from its burning. Similarities between suberin (major component of cork) and lignin suggest that fungi with high lignin degrading capacity could colonize cork residues. Basidiomycetes such as Lentinus edodes and Ganoderma lucidum, besides their capacity for degrading, are edible. Thus, while using them to degrade cork, it is also possible to obtain a food product. In this study, dry matter was reduced 40%, suberin was degraded 45%, oxidizable carbon was increased 35%, and Lentinus showed a high rate of growth. These results indicate that there is an environmental alternative to the elimination of residues from the cork industry.

Hypothalamic hypophyseal inhibitory factor (HHIF) increases intrasynaptosomal free calcium concentration

We have isolated from bovine hypothalamic and pituitary tissues a sodium pump inhibitor that is structurally different from ouabain. By mass spectrometric analysis, this purified factor revealed a single unique molecular ion with an accurate mass of 412.277 and a mass spectra different from that of ouabain. It has been previously shown that this factor inhibits the Ca2+, Mg(2+)-ATPase of the plasma membrane of synaptosomes. Because Ca2+ plays a major role in cellular excitability, we carried out a systematic study of the effects of this inhibitor on the Ca2+ transport processes across the plasma membrane of synaptosomes: We measured ATP-dependent calcium uptake, Na(+)-Ca2+ exchange, and passive permeability using 45Ca2+ and Millipore filtration, chlortetracycline fluorescence, and light-scattering, respectively. This factor inhibits the Na+, K(+)-ATPase activity of the synaptosomal plasma membrane vesicles in the same range of concentrations that produced an increase of intrasynaptosomal free calcium, with nearly the same K0.5 value. In addition, in this concentration range, this factor stimulated 10- to 11-fold the passive flux of Ca2+ and 2.5- to 3-fold the Ca2+ influx via the Na(+)-Ca2+ exchange in these membranes with respect to control values. Measurements of fluorescence anisotropy showed that in this concentration range, the inhibitor did not significantly change the order parameter (fluidity) of these membranes. These results suggest that besides its known inhibition of the sodium pump, this factor could play a role in the control of Ca2+ homeostasis by direct modulation of transport systems implicated in the control of intracellular calcium.

The interchain disulfide bond between TCR alpha beta heterodimers on human T cells is not required for TCR-CD3 membrane expression and signal transduction

In the present paper, it was attempted to define the amino acids or regions on TCR beta molecules that determine the TCR alpha-TCR beta interaction. Sequence studies on HBP-ALL variant cells with an intrinsic deficiency in TCR alpha beta dimer formation elucidated a conserved amino acid motif in the TCR-C beta beta-strand E, = Y(C)(L)(S)SRLR(V)(S)(A); this motif seems to represent one interaction area for the TCR alpha-TCR beta interaction. In addition, amino acids in the connecting peptide may be shaped in a precise structure (by the interactions with CD3 molecules?) involved in TCR alpha-TCR beta dimerization. This result was supported by the finding that the interchain disulfide bond between TCR alpha and beta chains is not required for membrane expression or transmembrane signal transduction of TCR alpha beta-CD3 complexes. Finally, comparative results from two membrane TCR-CD3-negative Jurkat variants R4.9 and E6.E12 suggest that TCR-C beta exon 1- and 2-encoded amino acids are important for the TCR beta-CD3 gamma epsilon association.

The tryptophan/histidine interaction in alpha-helices

Contacts between aromatic and charged residues are often found in proteins. Mutational studies have shown that a tryptophan/charged histidine pair can stabilise a protein by more than 1 kcal mol(-1). We have used circular dichroism and nuclear magnetic resonance to study the helical content of several peptides in which a tryptophan/histidine pair was placed at i, i + 3 or i, i + 4 in either the N to C or the C to N orientation. Our data indicate that the WH i, i + 4 geometry is the most stabilising one (when the histidine is protonated) and gives rise to the highest helical content. Little preference is observed among the three other orientations. The energy of the WH+ i, i + 4 interaction (calculated with AGADIR and SCINT) is about 1 kcal mol(-1). A statistical analysis of the occurrence of tryptophan/histidine pairs in alpha-helices of natural proteins reveals that, although the WH i, i + 4 pairs are not more abundant than the others, in most of the WH i, i + 4 pairs the two side-chains are in contact, but not in the other three orientations. These results suggest that the conformational stability of proteins could be increased by means of solvent-exposed intrahelical i, i + 4 tryptophan-histidine bridges and that these bridges could be useful to tailor the stability of helical peptides at physiological pH.

[Cerebral hemorrhage after carotid endarterectomy in a young adult]

INTRODUCTION

Cerebral haemorrhage after carotid endarterectomy is a rare complication. It follows 0.5% to 20% of all endarterectomies, but should be borne in mind because of the morbidity and mortality seen in most cases.

CLINICAL CASE

We describe the case of a 42 year old man in whom carotid endarterectomy had been done 7 days before to treat a stenosis of 80%. He complained of a sudden onset of weakness of the right half of his body and changes in his speech. Physical examination showed right inferior facial paresia, right hemiparesia and right extensor cutaneous plantar reflex. On admission to the Emergency Department, before treatment, blood pressure was 80/60. Carotid auscultation and palpation were normal. Cerebral TRC showed a left lenticular haematoma. The patient progressed satisfactorily.

DISCUSSION/CONCLUSIONS

We review the literature on the subject as well as the factors which should be considered as possibly predisposing to bleeding after carotid endarterectomy, such as arterial hypertension and occlusion or severe stenosis of the contralateral carotid artery. The detection of patients with the risk of postendarterectomy bleeding by simple noninvasive investigations, such as the transcranial doppler and the acetazolamide test, and early diagnosis of a clinical picture compatible with a hyperperfusion syndrome may contribute to the relief and prevention of sequelae in these patients.

Conformational stability of apoflavodoxin

Flavodoxins are alpha/beta proteins that mediate electron transfer reactions. The conformational stability of apoflavodoxin from Anaboena PCC 7119 has been studied by calorimetry and urea denaturation as a function of pH and ionic strength. At pH > 12, the protein is unfolded. Between pH 11 and pH 6, the apoprotein is folded properly as judged from near-ultraviolet (UV) circular dichroism (CD) and high-field 1H NMR spectra. In this pH interval, apoflavodoxin is a monomer and its unfolding by urea or temperature follows a simple two-state mechanism. The specific heat capacity of unfolding for this native conformation is unusually low. Near its isoelectric point (3.9), the protein is highly insoluble. At lower pH values (pH 3.5-2.0), apoflavodoxin adopts a conformation with the properties of a molten globule. Although apoflavodoxin at pH 2 unfolds cooperatively with urea in a reversible fashion and the fluorescence and far-UV CD unfolding curves coincide, the transition midpoint depends on the concentration of protein, ruling out a simple two-state process at acidic pH. Apoflavodoxin constitutes a promising system for the analysis of the stability and folding of alpha/beta proteins and for the study of the interaction between apoflavoproteins and their corresponding redox cofactors.