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M Goethals

Publications and source records attributed to M Goethals.

At least 37 records · Page 2Linked to original sources
PubMed1998

Contribution of the hydrophobicity gradient of an amphipathic peptide to its mode of association with lipids.

A class of peptides that associate with lipids, known as oblique-orientated peptides, was recently described [Brasseur R., Pillot, T., Lins, L., Vandekerckhove, J. & Rosseneu, M. (1997) Trends Biochem. Sci. 22, 167-171]. Due to an asymmetric distribution of hydrophobic residues along the axis of the alpha-helix, such peptides adopt an oblique orientation which can destabilise membranes or lipid cores. Variants of these oblique peptides, designed to have an homogeneous distribution of hydrophobic and hydrophilic residues along the helical axis, are classified as regular amphipathic peptides. These peptides are expected to lie parallel to the polar/apolar interface with their hydrophobic residues directed towards the apolar and their hydrophilic residues towards the polar phase. An hydrophobic, oblique-orientated peptide was identified at residues 56-68 in the sequence of the lecithin-cholesterol acyltransferase (LCAT), enzyme. This peptide is predicted to penetrate a lipid bilayer at an angle of 40 degrees through its more hydrophobic C-terminal end and thereby induce the destabilisation of a membrane or a lipid core. The LCAT-(56-68) wild-type peptide was synthesised together with the LCAT-(56-68, 0 degrees) variant, in which the hydrophobicity gradient was abolished through residue permutations. In two other variants, designed to keep their oblique orientation, the W61 residue was shifted either towards the more hydrophilic N-terminal at residue 57, or to position 68 at the hydrophobic C-terminal end of the peptide. Peptide-induced vesicle fusion was demonstrated by fluorescence measurements using pyrene-labeled vesicles and by monitoring of vesicle size by gel filtration. The interaction between peptides and lipids was monitored by measurement of the intrinsic tryptophan fluorescence emission of the peptides. Fluorescence polarisation measurements, using diphenyl hexatriene, were carried out to follow changes in the lipid fluidity. The LCAT-(56-68) wild-type peptide and the two oblique variants, induced fusion of unilamellar dimyristoylglycerophosphocholine vesicles. Tryptophan fluorescence emission measurements showed a 12-14 nm blue shift upon addition of the wild-type peptide and of the W61-->68 variant to lipids, whereas the fluorescence of the W61-->57 variant did not change significantly. This observation supports the insertion of the more hydrophobic C-terminal residues into the lipid phase, as predicted by the theoretical calculations. In contrast, the 0 degrees variant peptide had no fusogenic activity, and it associated with lipids to form small discoidal lipid/peptide complexes. The phospholipid transition temperature was decreased after addition of the wild-type, the W61-->68 and W61-->57 fusogenic peptides, whereas the opposite effect was observed with the 0 degrees variant. The behaviour of the wild-type and variant LCAT-(56-68) peptides stresses the contribution of the hydrophobicity gradient along the axis of an amphipathic peptide to the mode of association of this peptide with lipids. This parameter consequently influences the structural modifications occurring to lipids upon association with amphipathic peptides.

Catalytic Domain↗
PubMed1998

Enhanced efficiency of a targeted fusogenic peptide.

Membrane targeting was investigated as a potential strategy to increase the fusogenic activity of an isolated fusion peptide. This was achieved by coupling the fusogenic carboxy-terminal part of the beta-amyloid peptide (Abeta, amino acids 29-40), involved in Alzheimer's disease, to a positively charged peptide (PIP2-binding peptide, PBP) interacting specifically with a naturally occurring negatively charged phospholipid, phosphatidylinositol 4, 5-bisphosphate (PIP2). Peptide-induced vesicle fusion was spectroscopically evidenced by: (i) mixing of membrane lipids, (ii) mixing of aqueous vesicular contents, and (iii) an irreversible increase in vesicle size, at concentrations five to six times lower than the Abeta(29-40) peptide. In contrast, at these concentrations the PBP-Abeta(29-40) peptide did not display any significant activity on neutral vesicles, indicating that negatively charged phospholipids included as targets in the membranes, are required to compensate for the lower hydrophobicity of this peptide. When the alpha-helical structure of the chimeric peptide was induced by dissolving it in trifluoroethanol, an increase of the fusogenic potential of the peptide was observed, supporting the hypothesis that the alpha-helical conformation of the peptide is crucial to trigger the lipid-peptide interaction. The specificity of the interaction between PIP2 and the PBP moiety, was shown by the less efficient targeting of the chimeric peptide to membranes charged with phosphatidylserine. These data thus demonstrate that the specific properties of both the Abeta(29-40) and the PBP peptide are conserved in the chimeric peptide, and that a synergetic effect is reached through chemical linkage of these two fragments.

Dose-Response Relationship, Drug↗
PubMed1998

Different humoral responses during head-up tilt testing among patients with neurocardiogenic syncope.

Neurocardiogenic dysfunction is believed to result from activation of ventricular mechanoreceptors. To asses other humoral and circulatory mechanisms activated during vasovagal syncope, epinephrine, norepinephrine, renin, and aldosterone levels were measured during head-up tilt testing. Twenty-three patients referred because of vasovagal syncope underwent passive head-up tilt testing (80 degrees). Blood samples were taken at baseline, after 30 minutes of supine rest and at syncope. Five patients (four men, one woman; mean age 46 +/- 27 years) had cardioinhibitory syncope. Seven patients (five men, two women; mean age 40 +/- 12 years) had vasodepressor syncope. Eleven patients (eight men, three women; mean age 55 +/- 21 years) had negative results of head-up tilt tests. Among patients with cardioinhibitory syncope, norepinephrine concentration rose significantly from baseline to syncope (0.44 +/- 0.12 ng/ml versus 1.14 +/- 0.72 ng/ml; p < 0.05), whereas no significant change was observed in epinephrine (0.08 +/- 0.03 ng/ml versus 2.74 +/- 2.85 ng/ml; p = not significant [NS]), renin (5.68 +/- 3.03 pg/ml versus 19.58 +/- 11.47 pg/ml; p = NS), or aldosterone concentration (66.60 +/- 16.10 ng/ml versus 109.00 +/- 44.70 ng/ml; p = NS). Patients with vasodepressor syncope had a significant rise in renin (9.03 +/- 4.56 pg/ml versus 52.53 +/- 41.63 pg/ml; p < 0.05) and aldosterone concentration (95.43 +/- 103.03 ng/ml versus 249.57 +/- 191.54 ng/ml; p < 0.05), whereas no change in level of epinephrine (0.12 +/- 0.12 ng/ml versus 0.28 +/- 0.33 ng/ml; p = NS) or norepinephrine (0.60 +/- 0.26 ng/ml versus 0.86 +/- 0.53 ng/ml; p = NS) was detected. Among patients with negative results of tilt tests, levels of renin (7.94 +/- 7.19 pg/ml versus 27.71 +/- 18.50 pg/ml; p < 0.01) and aldosterone (64.64 +/- 28.33 ng/ml versus 160.91 +/- 79.58 ng/ml; p < 0.01) rose significantly, whereas no change was seen in epinephrine (0.12 +/- 0.14 ng/ml versus 0.23 +/- 0.31; p = NS) or norepinephrine concentration (0.54 +/- 0.21 ng/ml versus 0.82 +/- 0.52; p = NS). Patients with cardioinhibitory syncope were characterized by a rise in norepinephrine level and blunted activation of the renin-angiotensin-aldosterone axis at syncope. Unlike patients with cardioinhibitory syncope, the renin-angiotensin-aldosterone axis is activated in patients with vasodepressor syncope and patients with a negative result of head-up tilt test without a statistically significant increase in catecholamine levels. Patients with cardioinhibitory syncope have higher epinephrine levels at syncope compared with patients with a negative result of head-up tilt test and patients with vasodepressor syncope.

Adult↗
PubMed1998

Primary structure of scombrine alpha: two different species with an identical protamine.

We have studied the protamine scombrine alpha from the mackerel Scomber scombrus. Scombrine alpha is found phosphorylated in spermatid nuclei, but not in nuclei of ripe sperm. It is a typical fish protamine, made up of two distinct molecular species, each of 34 amino acid residues. The primary structure of the main component of scombrine alpha is 100% identical to scombrine gamma, the nonmicroheterogeneous protamine from Scomber australasicus (11). The second component of scombrine alpha is a very minor molecular species that has an isoleucine instead of a valine in position 11. Nuclear sperm-specific basic proteins display an enormous interspecific variability and it is very surprising that two different species show identical protamines. In this work we suggest that evolutionary changes in primary structure of protamines are restricted by several constitutive factors, especially when protamines either lack or have a low degree of microheterogeneity.

Amino Acid Sequence↗
PubMed1998

Use-dependent block of Ih in mouse dorsal root ganglion neurons by sinus node inhibitors.

1. The sinus node inhibitors UL FS 49 and DK-AH 269 reduce heart rate by slowing diastolic depolarization rate in the sino-atrial (SA) node, which might originate from the use-dependent blockade of a hyperpolarization-activated current If. A hyperpolarization-activated current Ih, which is present in many types of neurons, is similar to If. We studied the effects of these drugs on Ih in cultured mouse dorsal root ganglion (DRG) neurons. 2. With the whole-cell patch-clamp technique use-dependent block of Ih was observed. The steady-state block following a voltage-clamp pulse train (1-s steps from -38 to -108 mV applied at 0.5 Hz) was dependent on drug concentration and showed an apparent Kd of 0.1 and 0.79 microM with DK AH 269 and UL-FS 49 respectively. 3. The rate of block increased linearly with drug concentration. The rate of recovery from block was, however, much slower compared to cardiac tissue. 4. There was no significant effect of UL-FS 49 on the activation curve. 5. At high concentrations of UL-FS 49 a clear association of the drug with the open channel was observed. 6. When the cell was stimulated at a frequency of 3 Hz, a distinct hyperpolarization was observed in the presence of extracellular Cs+ or when Ih was blocked with UL-FS 49, but not in the absence of Cs+ and UL-FS 49. 7. These results indicate that Ih protects the cell against hyperpolarizations and subsequent inexcitability. The action of the drugs on the hyperpolarization-activated current in cardiac and neuronal tissue show some similarities; however, some pronounced differences indicate that different subtypes of the channel might exist.

Animals↗
PubMed1998

Early benefit of implantable cardioverter defibrillator therapy in patients waiting for cardiac transplantation.

The ICD can effectively recognize and treat ventricular arrhythmias that can lead to sudden death. Sudden death is a major problem in patients awaiting heart transplantation. We reviewed our experience with the ICD in patients with malignant ventricular arrhythmias waiting for cardiac transplantation. Nineteen patients were included. Seventeen were men, mean age was 54 +/- 11 years (range 17-66) and the left ventricular ejection fraction was 22% +/- 10% (range 9%-46%). After a mean follow-up of 6 +/- 5 months (range 1-20 months), 17 patients reached heart transplantation. One patient died and the other is waiting for a transplant. Before transplantation 71% of patients received an appropriate discharge. The mean time to the first appropriate discharge was 2 +/- 2 months (range < 1-6 months), which was significantly shorter than the mean time to first discharge in the other patients (n = 182) receiving a defibrillator in our center (11 +/- 10 months; range 1-58 months) (P < 0.0004). In conclusion, cardiac transplantation candidates with life-threatening ventricular arrhythmias can effectively be protected against sudden arrhythmic death by ICD. These patients have a high incidence of appropriate shocks occurring very early after implantation.

Adolescent↗
PubMed1997

Analogous F-actin binding by cofilin and gelsolin segment 2 substantiates their structural relationship.

Cofilin is representative for a family of low molecular weight actin filament binding and depolymerizing proteins. Recently the three-dimensional structure of yeast cofilin and of the cofilin homologs destrin and actophorin were resolved, and a striking similarity to segments of gelsolin and related proteins was observed (Hatanaka, H., Ogura, K., Moriyama, K., Ichikawa, S., Yahara, I., and Inagaka, F. (1996) Cell 85, 1047-1055; Fedorov, A. A., Lappalainen, P., Fedorov, E. V., Drubin, D. G., and Almo, S. C. (1997) Nat. Struct. Biol. 4, 366-369; Leonard, S. A., Gittis, A. G., Petrella, E. C., Pollard, T. D., and Lattman, E. E. (1997) Nat. Struct. Biol. 4, 369-373). Using peptide mimetics, we show that the actin binding site stretches over the entire cofilin alpha-helix 112-128. In addition, we demonstrate that cofilin and its actin binding peptide compete with gelsolin segments 2-3 for binding to actin filaments. Based on these competition data, we propose that cofilin and segment 2 of gelsolin use a common structural topology to bind to actin and probably share a similar target site on the filament. This adds a functional dimension to their reported structural homology, and this F-actin binding mode provides a basis to further enlighten the effect of members of the cofilin family on actin filament dynamics.

Actin Depolymerizing Factors↗
PubMed1997

A prospective hemodynamic evaluation of patients with chronic atrial fibrillation undergoing radiofrequency catheter ablation of the atrioventricular junction.

A prospective invasive hemodynamic evaluation in 11 unselected patients with medically refractory chronic atrial fibrillation undergoing radiofrequency catheter ablation of the atrioventricular junction was performed. The resultant rate regulation and control caused a hemodynamic and symptomatic improvement despite persistent fibrillation at the atrial level.

Aged↗
PubMed1997

The 118-135 peptide of the human prion protein forms amyloid fibrils and induces liposome fusion.

The prion protein (PrPC) is a glycoprotein of unknown function normally found at the surface of neurons and of glial cells. It is involved in diseases such as bovine spongiform encephalopathy, and Creutzfeldt-Jakob disease in the human, where PrPC is converted into an altered form (termed PrPSc). PrPSc is highly resistant towards proteolytic degradation and accumulates in the central nervous system of affected individuals. By analogy with the pathological events occuring during the development of Alzheimer's disease, controverses still exist regarding the relationship between amyloidogenesis, prion aggregation and neuronal loss. To unravel the mechanism of PrP neurotoxicity and understand the interaction of PrP with cellular membranes, a series of natural and variant peptides spanning residues 118 to 135 of PrP was synthesized. The potential of these peptides to induce fusion of unilamellar lipid vesicles was investigated. According to computer modeling calculations, the 120 to 133 domain of PrP is predicted to be a tilted lipid-associating peptide, and to insert in a oblique way into a lipid bilayer through its N-terminal end. In addition to amyloidogenic properties exhibited in vitro by these peptides, peptide-induced vesicle fusion was demonstrated by several techniques, including lipid- and core-mixing assays. Elongation of the 120 to 133 peptide towards the N- and C-terminal ends of the PrP sequence showed that the 118 to 135 PrP peptide has maximal fusogenic properties, while the variant peptides had no effect. Due to their high hydrophobicity, all peptides tested were able to interact with liposomes to induce leakage of encapsulated calcein. We demonstrate also that the propensity of the peptides to fold as an alpha-helix increases their fusogenic activity, thus accounting for the maximal fusogenic activity of the most stable helix at residues 118 to 135. These data suggest that, by analogy with the C-terminal domain of the beta-amyloid peptide, the fusogenic properties exhibited by the prion peptides might contribute to the neurotoxicity of these peptides by destabilizing cellular membranes.

Amino Acid Sequence↗
PubMed1997

Structural and functional properties of the 154-171 wild-type and variant peptides of human lecithin-cholesterol acyltransferase.

The 154-171 segment of the human lecithin-cholesterol acyltransferase (LCAT) enzyme was identified as the most stable amphipathic helix in the LCAT sequence. Its mean hydrophobicity, hydrophobic moment and its orientation at a lipid/water interface are similar to those of some of the helical repeats of apolipoprotein A-IV and E. This domain was therefore proposed as a candidate peptide accounting for the association between LCAT and its lipid substrate. To investigate this hypothesis we synthesized the LCAT-(154-171)-peptide, two variants containing the natural Y156N and R158C mutations and a variant with increased hydrophobicity through Y156I, L160I, L163I and Y171W substitutions. The structural and lipid-binding properties of these synthetic peptides were investigated by turbidity, fluorescence, electron microscopy and circular dichroism. The wild-type peptide, the R158C variant in its dimeric form, as well as the more hydrophobic peptide, associated with phospholipids, whereas the Y156N and the R158C variant in its monomeric form did not. However, only the complexes generated with the hydrophobic variant were stable enough to resist dissociation during gel filtration. The wild-type peptide and hydrophobic variant formed discoidal complexes with dimyristoylglycerophosphocholine (Myr2GroPCho) as shown by negative staining electron microscopy. Comparison of the properties of the wild-type and hydrophobic variant LCAT-(154-171)-peptide stresses the contribution of the hydrophobic face of the amphipathic helix to the formation and stabilization of the peptide/lipid complexes. This is further confirmed by the decreased affinity of the Y156N variant peptide for lipids, as this mutation decreased the mean hydrophobicity of the hydrophobic face of the amphipathic helix. These results support the hypothesis that the 154-171 segment of LCAT might be involved in the interaction of the enzyme with its lipid substrate and suggest that the decreased activity of the Y156N natural LCAT mutant might result from a decreased affinity of this mutant for lipids.

Amino Acid Sequence↗
PubMed1997

Identification of two regions in the N-terminal domain of ActA involved in the actin comet tail formation by Listeria monocytogenes.

The ActA protein of Listeria monocytogenes induces actin nucleation on the bacterial surface. The continuous process of actin filament elongation provides the driving force for bacterial propulsion in infected cells or cytoplasmic extracts. Here, by fusing the N-terminus of ActA (residues 1-234) to the omega fragment of beta-galactosidase, we present the first evidence that this domain contains all the necessary elements for actin tail formation. A detailed analysis of ActA variants, in which small fragments of the N-terminal region were deleted, allowed the identification of two critical regions. Both are required to initiate the actin polymerization process, but each has in addition a specific role to maintain the dynamics of the process. The first region (region T, amino acids 117-121) is critical for filament elongation, as shown by the absence of actin tail in a 117-121 deletion mutant or when motility assays are performed in the presence of anti-region T antibodies. The second region (region C, amino acids 21-97), is more specifically involved in maintenance of the continuity of the process, probably by F-actin binding or prevention of barbed end capping, as strongly suggested by both a deletion (21-97) leading to 'discontinuous' actin tail formation and in vitro experiments showing that a synthetic peptide covering residues 33-74 can interact with F-actin. Our results provide the first insights in the molecular dissection of the actin polymerization process induced by the N-terminal domain of ActA.

Actins↗
PubMed1997

The mammalian profilin isoforms display complementary affinities for PIP2 and proline-rich sequences.

We present a study on the binding properties of the bovine profilin isoforms to both phosphatidylinositol 4,5-bisphosphate (PIP2) and proline-rich peptides derived from vasodilator-stimulated phosphoprotein (VASP) and cyclase-associated protein (CAP). Using microfiltration, we show that compared with profilin II, profilin I has a higher affinity for PIP2. On the other hand, fluorescence spectroscopy reveals that proline-rich peptides bind better to profilin II. At micromolar concentrations, profilin II dimerizes upon binding to proline-rich peptides. Circular dichroism measurements of profilin II reveal a significant conformational change in this protein upon binding of the peptide. We show further that PIP2 effectively competes for binding of profilin I to poly-L-proline, since this isoform, but not profilin II, can be eluted from a poly-L-proline column with PIP2. Using affinity chromatography on either profilin isoform, we identified profilin II as the preferred ligand for VASP in bovine brain extracts. The complementary affinities of the profilin isoforms for PIP2 and the proline-rich peptides offer the cell an opportunity to direct actin assembly at different subcellular localizations through the same or different signal transduction pathways.

Amino Acid Sequence↗
PubMed1997

Specific modulation of the fusogenic properties of the Alzheimer beta-amyloid peptide by apolipoprotein E isoforms.

C-terminal fragments of the Alzheimer amyloid peptide (amino acids 29-40 and 29-42) have physico-chemical properties related to those of the fusion peptides of viral proteins and they are able to induce the fusion of liposomes in vitro. We proposed that these properties could mediate a direct interaction of the amyloid peptide with cell membranes and account for part of the cytotoxicity of the amyloid peptide. In view of the epidemiologic and biochemical linkages between the pathology of Alzheimer's disease and apolipoprotein E (apoE) polymorphism, we examined the potential interaction between the three common apoE isoforms and the C-terminal fragments of the amyloid peptide. We show that, at low concentration, only apoE2 and apoE3 are potent inhibitors of the amyloid peptide fusogenic and aggregational properties, whereas the apoE4 isoform has no effect. We further show that the protective effect of apoE is mediated by the formation of stable apoE/amyloid peptide complexes, as determined by tryptophan emission fluorescence measurements and by gel electrophoresis. The interaction specificity between apoE2 and apoE3 and the amyloid fragments is demonstrated here, since other apolipoproteins (e.g. apolipoprotein A-I and A-II), with similar amphipathic structures, do not interact with the amyloid C-terminal fragments. Finally, we show that, reciprocally, the amyloid peptide can interact directly with the apoE2 and apoE3 isoforms to decrease or perturb their normal association with lipids. These data suggest that the 29-40 and 29-42 domains of the amyloid peptide could be critical for the amyloid-apoE interaction, and that apoE2 and apoE3 isoforms, but not apoE4, could play a protective role against the formation of amyloid aggregates and/or against their interaction with cellular membranes.

Amyloid beta-Peptides↗
PubMed1997

Effect of cAMP and ATP on the hyperpolarization-activated current in mouse dorsal root ganglion neurons.

In mouse dorsal root ganglion (DRG) neurons the activation curve of the hyperpolarization-activated current (Ih) shifted towards depolarized potentials when cAMP was present in the pipette. The relation between the midpoint potential and cAMP concentration could be described by a Hill function with a half-maximal concentration of 0.55 microM cAMP, reflecting a direct action of cAMP on the channel. With 5 mM ATP and a saturating concentration of cAMP an additional shift of the midpoint potential is observed which can be explained by phosphorylation. Application of Rp-cAMPS and Sp-cAMPS support the hypothesis of both a phosphorylation pathway and a direct effect exhibited by these molecules. The bell-shaped curves, relating the time constants for the slow and fast current components to the voltage, shifted towards positive membrane potentials when cAMP and ATP were in the pipette. The fully activated Ih/voltage relation and the reversal potential were not dependent on the presence of cAMP or ATP in the pipette. The mean resting membrane potential of -59 mV, using the perforated-patch configuration, hyperpolarized in the presence of extracellular CsCl. In the whole-cell configuration the resting membrane potential was significantly more negative at 0 microM cAMP (-61 mV) than at 100 microM cAMP (-57 mV). Thus, the activation of Ih, regulated by both the intracellular cAMP and the ATP concentration, may influence the excitability of DRG neurons.

Adenosine Triphosphate↗
PubMed1997

Hemodynamic deterioration following radiofrequency ablation of the atrioventricular conduction system.

Radiofrequency ablation of the atrioventricular conduction system (ACS) has become an established therapy for patients with drug refractory atrial fibrillation. We observed eight patients with hemodynamic deterioration after radiofrequency ablation of the atrioventricular conduction system. As we found hemodynamic deterioration related to worsening mitral regurgitation, we compared the clinical history, electrophysiological, and echocardiographic data from the patients with hemodynamic deterioration and worsening mitral regurgitation (group 1) to those without hemodynamic deterioration and stable mitral regurgitation after the procedure (group 2). Eight out of 108 patients (7.4%) undergoing ablation of the ACS deteriorated hemodynamically with acute pulmonary edema in three and congestive heart failure in five patients occurring at a mean of 3 and 8 weeks, respectively, after the procedure. Three of these patients were referred for mitral valve surgery. Two patients underwent ablation using a left-sided approach. A right-sided approach was used in five patients. In one patient, a left- and right-sided approach was used. Compared to group 2 patients, group 1 patients had significantly higher left ventricular end-diastolic diameters (64 +/- 6 mm vs 56 +/- 9 mm) at baseline despite similar fractional shortening (32% +/- 11% vs 34% +/- 13%), left ventricular end-systolic diameters (43 +/- 9 mm vs 36 +/- 7 mm) and degree of mitral regurgitation (1.4 +/- 1.1 vs 1.4 +/- 0.7) on echocardiographic analysis. Thus, hemodynamic deterioration together with progression of mitral regurgitation is a potential complication of ablation of the ACS (up to 7.4%). Patients with high left ventricular end-diastolic diameters and moderate mitral regurgitation at baseline seem prone to this complication.

Adult↗
PubMed1997

Molecular cloning, over-expression, developmental regulation and immunolocalization of fragminP, a gelsolin-related actin-binding protein from Physarum polycephalum plasmodia.

FragminP is a Ca2+-dependent actin-binding and microfilament regulatory protein of the gelsolin family. We screened a Physarum polycephalum cDNA library with polyclonal fragminP antibodies and isolated a cDNA clone of 1,104 bp encoding 368 amino acids of fragminP, revealing two consensus phosphatidylinositol 4,5 bisphosphate-binding motifs in the central part of the protein. The first methionine is modified by an acetyl group, and three amino acids were missing from the protein coded for by the cDNA clone. Full-length recombinant fragminP was generated by PCR, purified after over-expression from Escherichia coli and displayed identical properties to native Physarum fragminP. Northern blot analysis against RNA, isolated from cultures at various stages of development, indicated that fragminP is absent from amoebae and that expression is initiated at an early stage during apogamic development, in a similar way to that observed for the profilin genes. In situ immunolocalization of fragminP in Physarum microplasmodia revealed that the protein is localized predominantly at the plasma membrane, suggesting a role in the regulation of the subcortical actin meshwork. Our data indicate that we have isolated the plasmodium-specific fragminP cDNA (frgP) and suggest that, in each of its two vegetative cell types, P. polycephalum uses a different fragmin isoform that performs different functions.

Actins↗
PubMed1997

Differences in the trabecular meshwork between Belgian and Congolese patients with open-angle glaucoma.

PURPOSE: To study the alterations of the trabecular meshwork of Belgian and Congolese patients with open angle glaucoma (OAG). METHODS: A trabeculectomy was performed in 27 OAG patients from Belgium and 24 from Congo; the trabecular specimens were fixed, embedded, stained, and studied by light microscopy. These specimens were compared with the trabecular meshworks from 5 Belgian non-glaucomatous eyes. RESULTS: The mean number (+/- standard deviation) of trabecular cells per field was 69 (+/- 10) in Belgian normal eyes, 34 (+/- 17) in Belgian OAG patients, and 10 (+/- 6) in Congolese OAG patients. The trabecular meshwork was collapsed and Schlemm's canal was closed in the cases with a diminished number of cells. Pigmentation was present in 79% of the Congolese and in 35% of the Belgian specimens. CONCLUSION: The trabecular meshwork from OAG patients has a lower cellularity than normal, and the effect is much more pronounced in the trabecular meshwork from Congolese patients. This may be a possible explanation for the racial differences in OAG and the more severe forms of glaucoma in black people.

Aged↗