Case study of circadian rhythm sleep disorder following haloperidol treatment: reversal by risperidone and melatonin

A patient with Gilles de la Tourette syndrome treated with haloperidol, ingested once daily after awakening from sleep, exhibited an irregular sleep-wake pattern with a free-running component of approximately 48 h. Transfer to risperidone, ingested once daily after awakening from sleep, was beneficial resulting in a sleep-wake cycle more synchronized at the appropriate phase to the external zeitgebers, and fewer nocturnal disturbances. The circadian sleep-wake schedule was fully synchronized when the patient had been subsequently treated with melatonin at 21:00h, before intended nocturnal sleep, in addition to risperidone in the morning. Restoration of the sleep-wake circadian pattern was accompanied by the patient's subjective report of significant improvement in his quality of life, social interactions, and occupational status. This observation suggests that circadian rhythm sleep disorders can be related to the typical neuroleptic haloperidol and restored by the atypical neuroleptic risperidone. Similar findings reported in patients suffering from other disorders support the hypothesis that the described disruption of the sleep-wake schedule is medication rather than illness-related. Therefore, it is very important to realize that circadian rhythm sleep disorders may be a side effect of neuroleptics.     

Identification of the bacteria-binding peptide domain on salivary agglutinin (gp-340/DMBT1), a member of the scavenger receptor cysteine-rich superfamily

Salivary agglutinin is encoded by DMBT1 and identical to gp-340, a member of the scavenger receptor cysteine-rich (SRCR) superfamily. Salivary agglutinin/DMBT1 is known for its Streptococcus mutans agglutinating properties. This 300-400 kDa glycoprotein is composed of conserved peptide motifs: 14 SRCR domains that are separated by SRCR-interspersed domains (SIDs), 2 CUB (C1r/C1s Uegf Bmp1) domains, and a zona pellucida domain. We have searched for the peptide domains of agglutinin/DMBT1 responsible for bacteria binding. Digestion with endoproteinase Lys-C resulted in a protein fragment containing exclusively SRCR and SID domains that binds to S. mutans. To define more closely the S. mutans-binding domain, consensus-based peptides of the SRCR domains and SIDs were designed and synthesized. Only one of the SRCR peptides, designated SRCRP2, and none of the SID peptides bound to S. mutans. Strikingly, this peptide was also able to induce agglutination of S. mutans and a number of other bacteria. The repeated presence of this peptide in the native molecule endows agglutinin/DMBT1 with a general bacterial binding feature with a multivalent character. Moreover, our studies demonstrate for the first time that the polymorphic SRCR domains of salivary agglutinin/DMBT1 mediate ligand interactions.     

Cholesteryl ester flux from HDL to VLDL-1 is preferentially enhanced in type IIB hyperlipidemia in the postprandial state

Postprandial triglyceride-rich lipoproteins (TRL) exert proatherogenic effects at the arterial wall, including lipid deposition. Following consumption of a mixed meal (1200 kcal), plasma-mediated cellular free cholesterol (FC) efflux, lecithin:cholesterol acyltransferase (LCAT), and cholesteryl ester transfer protein (CETP) activities were determined in subjects (n = 12) displaying type IIB hyperlipidemia and compared with those in a normolipidemic control group (n = 14). The relative capacity of plasma to induce FC efflux from Fu5AH cells via the SR-BI receptor was significantly increased 4 h postprandially (+23%; P < 0.005) in the type IIB group, whereas it remained unchanged for postprandial plasma from normolipidemic subjects. LCAT activity was significantly elevated 2 h postprandially in both the IIB and control groups, (+46% and +36%, respectively; P < 0.005 vs. respective baseline value). In type IIB subjects, total cholesteryl ester (CE) mass transfer from HDL to total TRL [chylomicrons (CMs) + VLDL-1 + VLDL-2 + IDL] increased progressively from 15 +/- 2 micro g CE/h/ml at baseline to 28 +/- 2 micro g CE transferred/h/ml (+87%; P = 0.0004) at 4 h postprandially. CE transfer to CMs and VLDL-1 was preferentially stimulated (2.6-fold and 2.3-fold respectively) at 4 h in IIB subjects and occurred concomitantly with elevation in mass and particle number of both CMs (2.3-fold) and VLDL-1 (1.3-fold). Furthermore, in type IIB subjects, CETP-mediated total CE flux over the 8 h postprandial period from HDL to potentially atherogenic TRL was significantly enhanced, and notably to VLDL-1 (32-fold elevation; P < 0.005), relative to control subjects. Such CE transfer flux was reflected in a significant postprandial increase in CE-TG ratio in both CMs and VLDL-1 in type IIB plasmas. In conclusion, HDL-CE is preferentially targeted to VLDL-1 via the action of CETP during alimentary lipemia, thereby favoring formation and accumulation of atherogenic CE-rich remnant particles.     

Direct interaction of dermaseptin S4 aminoheptanoyl derivative with intraerythrocytic malaria parasite leading to increased specific antiparasitic activity in culture

Antiplasmodial activity of the dermaseptin S4 derivative K(4)S4(1-13) (P) was shown to be mediated by lysis of the host cells. To identify antiplasmodial peptides with enhanced selectivity, we produced and screened new derivatives based on P and singled out the aminoheptanoylated peptide (NC7-P) for its improved antiplasmodial properties. Compared with P, NC7-P displayed both increased antiparasitic efficiency and reduced hemolysis, including against infected cells. Antiplasmodial activity of P and its derivative was time-dependent and irreversible, implying a cytotoxic effect. But, whereas the dose dependence of growth inhibition and hemolysis of infected cells overlapped when treated with P, NC7-P exerted more than 50% growth inhibition at peptide concentrations that did not cause hemolysis. Noticeably, NC7-P but not P, dissipated the parasite plasma membrane potential and caused depletion of intraparasite potassium at nonhemolytic conditions. Confocal microscopy analysis of infected cells localized the rhodaminated derivative in association with parasite membranes and intraerythrocytic tubulovesicular structures, whereas in normal cells, the peptide localized exclusively at the plasma membrane. Overall, the data demonstrate that antimicrobial peptides can be engineered to act specifically on the membrane of intracellular parasites and support a mechanism whereby NC7-P crosses the host cell plasma membrane and disrupts the parasite membrane(s).     

Structure of apo-phosphatidylinositol transfer protein alpha provides insight into membrane association

Phosphatidylinositol transfer protein alpha (PITP alpha) is a ubiquitous and highly conserved protein in multicellular eukaryotes that catalyzes the exchange of phospholipids between membranes in vitro and participates in cellular phospholipid metabolism, signal transduction and vesicular trafficking in vivo. Here we report the three-dimensional crystal structure of a phospholipid-free mouse PITP alpha at 2.0 A resolution. The structure reveals an open conformation characterized by a channel running through the protein. The channel is created by opening the phospholipid-binding cavity on one side by displacement of the C-terminal region and a hydrophobic lipid exchange loop, and on the other side by flattening of the central beta-sheet. The relaxed conformation is stabilized at the proposed membrane association site by hydrophobic interactions with a crystallographically related molecule, creating an intimate dimer. The observed open conformer is consistent with a membrane-bound state of PITP and suggests a mechanism for membrane anchoring and the presentation of phosphatidylinositol to kinases and phospholipases after its extraction from the membrane. Coordinates have been deposited in the Protein Data Bank (accession No. 1KCM).     

Characterization of SP1, a stress-responsive,boiling-soluble,homo-oligomeric protein from aspen

In flowering plants, the vegetative nucleus and the two sperm cells are proposed to form a functional assemblage, the male germ unit (MGU). Here, we describe the developmental pathway of MGU assembly in Arabidopsis and report two classes of mutations that affect the integrity and/or the positioning of the MGU in the mature pollen grain. In germ unit malformed (gum) mutants, the vegetative nucleus is positioned adjacent to the pollen grain wall, separate from the two sperm cells, whereas in MGU displaced (mud) mutants, the intact MGU is displaced to the pollen grain wall. mud and gum mutants correspond to male-specific gametophytic mutations that also reduce pollen fitness. Genetic mapping showed that the gum1 and gum2 mutations are genetically linked, possibly allelic, whereas the mud1 and mud2 mutations correspond to two unlinked loci mapping on different chromosomes. The hierarchical relationship between mud and gum mutations was investigated by phenotypic analysis of double mutants. gum1 appeared to act earlier than mud1 and mud2, affecting initial MGU assembly and its stability during pollen maturation. In contrast, mud1 and mud2 mutations appear to act only on MGU positioning during final maturation. From in planta analyses of pollen germination in mud and gum mutants, we conclude that the initial proximity and positioning of MGU components is not required for their entrance into the pollen tube, but the efficiency of MGU translocation is reduced.     

Three-dimensional localization of ultrasmall immuno-gold labels by HAADF-STEM tomography

The localization of scarce antigens in thin sections of biological material can be accomplished by pre-embedment labeling with ultrasmall immuno-gold labels. Moreover, with this method, labeling is not restricted to the section surface but occurs throughout the section volume. Thus, when combined with electron tomography, antigens can be localized in three dimensions in relation to the 3D (three-dimensional) ultrastructure of the cell. However, for visualization in a transmission electron microscope, these labels need to be enlarged by silver or gold enhancement. The increase in particle size reduces the resolution of the antigen detection and the large particles obscure ultrastructural details in the tomogram. In this paper we show for the first time that these problems can be avoided and that ultrasmall gold labels can be localized in three dimensions without the need for gold or silver enhancement by using HAADF-STEM (high angular annular dark-field-scanning transmission electron microscopy) tomography. This method allowed us to three-dimensionally localize Aurion ultrasmall goat anti-rabbit immuno-gold labels on sections of Epon-embedded, osmium-uranium-lead-stained biological material. Calculations show that a 3D reconstruction obtained from HAADF-STEM projection images can be spatially aligned to one obtained from transmission electron microscopy (TEM) projections with subpixel accuracy. We conclude that it is possible to combine the high-fidelity structural information of TEM tomograms with the ultrasmall label localization ability of HAADF-STEM tomograms.     

The involvement of IL-6 and IL-8 in acute invasive gastroenteritis of children

The involvement of the proinflammatory cytokines, interleukin 8 (IL-8) and 6 (IL-6), was studied during the first 72 h of acute invasive gastroenteritis. Study population included 33 infants and young children aged six months to six years and seven age-matched controls. As a group, patients with acute invasive gastroenteritis had an increased serum level of IL-8 and IL-6 as compared with healthy controls (p < 0.002 and p < 0.001, respectively). Subjects were then divided into two groups based on stool cultures (proven and non-proven bacterial cultures). Patients with bacterial-proven acute invasive gastroenteritis tended to have increased IL-8 serum concentrations (p < 0.07) as compared with those with non-proven bacterial etiologies and IL-6 levels were only detected in subjects with positive bacterial cultures (p < 0.05). When dividing each sub-group into early and late blood drawing with respect to disease onset, no statistical differences were found in each group but subjects with bacterial-proven etiologies had significant higher IL-6 levels as compared with non-proven etiologies at the two time points (p < 0.019 and p < 0.015, respectively).In conclusion, the proinflammatory cytokines, IL-6 and IL-8, are involved in acute invasive gastroenteritis. The difference in IL-6, and to a lesser degree IL-8, between proven and non-proven bacterial etiologies, needs further investigation.     

Involvement of the endoplasmic reticulum in peroxisome formation

The traditional view holds that peroxisomes are autonomous organelles multiplying by growth and division. More recently, new observations have challenged this concept. Herein, we present evidence supporting the involvement of the endoplasmic reticulum (ER) in peroxisome formation by electron microscopy, immunocytochemistry and three-dimensional image reconstruction of peroxisomes and associated compartments in mouse dendritic cells. We found the peroxisomal membrane protein Pex13p and the ATP-binding cassette transporter protein PMP70 present in specialized subdomains of the ER that were continuous with a peroxisomal reticulum from which mature peroxisomes arose. The matrix proteins catalase and thiolase were only detectable in the reticula and peroxisomes. Our results suggest the existence of a maturation pathway from the ER to peroxisomes and implicate the ER as a major source from which the peroxisomal membrane is derived.