Geographical and temporal conservation of antibody recognition of Plasmodium falciparum variant surface antigens

The slow acquisition of protection against Plasmodium falciparum malaria probably reflects the extensive diversity of important antigens. The variant surface antigens (VSA) that mediate parasite adhesion to a range of host molecules are regarded as important targets of acquired protective immunity, but their diversity makes them questionable vaccine candidates. We determined levels of VSA-specific immunoglobulin G (IgG) in human plasma collected at four geographically distant and epidemiologically distinct localities with specificity for VSA expressed by P. falciparum isolates from three African countries. Plasma levels of VSA-specific IgG recognizing individual parasite isolates depended on the transmission intensity at the site of plasma collection but were largely independent of the geographical origin of the parasites. The total repertoire of immunologically distinct VSA thus appears to be finite and geographically conserved, most likely due to functional constraints. Furthermore, plasma samples frequently had high IgG reactivity to VSA expressed by parasites isolated more than 10 years later, showing that the repertoire is also temporally stable. Parasites from patients with severe malaria expressed VSA (VSASM) that were better recognized by plasma IgG than VSA expressed by other parasites, but importantly, VSASM-type antigens also appeared to show substantial antigenic homogeneity. Our finding that the repertoire of immunologically distinct VSA in general, and in particular that of VSASM, is geographically and temporally conserved raises hopes for the feasibility of developing VSA-based vaccines specifically designed to accelerate naturally acquired immunity, thereby enhancing protection against severe and life-threatening P. falciparum malaria.     

Goblet cells in the normal adult human larynx--studies on morphology, distribution and density

From 12 clinically and macroscopically normal larynges from adult persons all the mucosa was prepared and stained with PAS-alcian blue to study the morphology, distribution, and density of the goblet cells. In each larynx goblet cells were counted in 600 fields of 0.01768 mm2 mucosal surface, distributed on 18, 18 and 24 localities in the subglottis, glottis with the sinus of Morgagni, and supraglottis respectively. The goblet cells form a continuous pattern, comprising the entire subglottis, the anterior commissure, the sinus of Morgagni, the false vocal cords, vestibule of the larynx, and reaching to the cranial part of the laryngeal surface of the epiglottis. Another continuous, but goblet cell-free area extended from a couple of mm posterior to the anterior commissure, posteriorad on the cranial surface of the vocal cords, ary regions, aryepiglottic fold, the edge of the epiglottis, and 4-5 mm of the laryngeal surface of the epiglottic top, epiglottic vallecula, piriform recess, and the postcricoid region. Between the pseudostratified, ciliated columnar epithelium with goblet cells and the goblet cell-free stratified squamous epithelium there is a transitional epithelium in which the goblet cells alter from the 40 micron tall goblet cells characteristic of the respiratory tract epithelium to being quite flattened in order to disappear completely in the stratified squamous epithelium. The goblet cell density is significantly lower in the subglottis, viz. 125 cells per field, than in the glottis with the sinus of Morgagni and supraglottis, where the median density is 166 and 161 cells respectively per field. A possible correlation between the influence of the respiratory air upon the density of goblet cells and the complex anatomy of the larynx is discussed.     

Prevalence of antibodies against heat-stable antigens from Helicobacter pylori in patients with dyspeptic symptoms and normal persons.

Heat-stable antigens from Helicobacter pylori were investigated for the detection of serum IgG, IgA and IgM antibodies against H. pylori by an ELISA technique. Antibody titers against H. pylori were measured in 167 dyspeptic patients, of whom 96 were H. pylori positive confirmed by culture or microscopy, and in 482 controls (0-98 years). Increased IgG antibody titers were found significantly more often in dyspeptic patients with active chronic gastritis than in patients with normal morphology, as well as in H. pylori-positive patients as compared to H. pylori-negative patients, independent of the endoscopic findings. The heat-stable antigens were compared with acid glycine-extracted antigens and a high degree of concordance was found in the results obtained with the two antigen preparations. The differences in the IgA antibody titers against H. pylori between H. pylori-positive and H. pylori-negative dyspeptic patients were significant and may be useful to confirm a borderline IgG result. No differences were found in IgM antibody titer between H. pylori-positive and -negative patients. The greatest age-dependent increase in IgG and IgA antibody titers was found in children, and if a lower cut-off level is used for children than for adults, as has been proposed, the proportion of people with increased antibody titers against H. pylori would be almost constant from the age of between five and 10 years until the time between 61 and 80 years. Comparison of H. pylori IgG antibodies with IgG antibodies against Campylobacter jejuni and total antibodies against cytomegalovirus (CMV) showed a greater similarity between H. pylori and C. jejuni (R = 0.51) than between H. pylori and CMV (R = 0.22). This may possibly be caused by cross-reactions between H. pylori and C. jejuni. The H. pylori heat-stabile antigen seems not to be very different from other crude H. pylori antigens like acid glycine-extracted antigens, but purification and characterization of the antigens are needed to improve antibody assays.     

Fatal familial cholestatic syndrome in Greenland Eskimo children

Summary We report the first detailed study of hepatic morphlogy in 28 biopsies from 16 Greenland Eskimo children with fatal familial cholestatic syndrome. The changes were categorized as early, intermediate and late. In the early stage, until 5 months of age, changes were restricted to zone 3, consisting of cholestasis and rosette formation without fibrosis. In the intermediate stage, from 5 to 14 months, cholestasis persisted and rosette formation increased, both with further extension into zone 2. Perisinusoidal fibrosis developed, first in zone 3 and later in zone 1. The late stage, from 17 to 60 months, showed a further increase in cholestasis and rosette formation, and fibrosis of zones 3 and 1 in nearly all biopsies. Portal to portal and portal to central fibrosis was evident with resulting cirrhosis in 2 of 7 patients. The morphological features can be summarized as pure cholestasis with prominent rosette formation followed by zone 3 fibrosis, zone 1 fibrosis, and, cirrhosis. Other characteristics are the virtual absence of inflammation and the lack of anatomical abnormalities such as paucity of bile ducts. The changes and their progression resemble those of Byler disease. Clinical and biochemical features are also largely similar, except for the presence of thrombocytosis in many of the Eskimo patients.     

'Vanishing embryo syndrome' in IVF/ICSI

BACKGROUND: In a Danish population-based cohort study assessing the risk of cerebral palsy in children born after IVF, we made some interesting observations regarding 'vanishing co-embryos'. METHODS and RESULTS: All live-born children born in Denmark from 1 January 1995 to 31 December 2000 were included in this analysis. The children conceived by IVF/ICSI (9444) were identified through the IVF Register, the children conceived without IVF/ICSI (395 025) were identified through The Danish Medical Birth Register. Main outcome measure was the incidence of cerebral palsy. Within the IVF/ICSI children we found indications of an increased risk of cerebral palsy in those children resulting from pregnancies, where the number of embryos transferred was higher than the number of children born. CONCLUSIONS: The association between vanishing embryo syndrome and incidence of cerebral palsy following IVF requires further investigation in larger, adequately powered, studies.     

Severe hypertension with cerebral symptoms treated with furosemide, fractionated diazoxide or dihydralazine. Danish Multicenter Study

Emergency treatment of acute, severe hypertension defined as diastolic blood pressure (DBP) greater than or equal to 135 mmHg combined with cerebral symptoms was prospectively monitored in a randomized multicenter study including 64 patients. Treatment was divided into two periods. In the first hour the patients were observed in the supine position after being given 40 mg furosemide intravenously. If DBP remained greater than 125 mmHg (n = 52), the patients were put on fractionated diazoxide administered intravenously (n = 28) or dihydralazine administered intramuscularly (n = 24). Blood pressure (BP) decreased with diazoxide from an average of 241/149 mmHg to 180/111 mmHg after 5 hours and with dihydralazine from 237/149 to 161/101 mmHg. The inter-individual BP response varied considerably. A clear and identical regression in neurological symptoms was observed on both drug regimens. No new neurological symptoms were seen to develop. It is concluded that a gradual fall in BP can be obtained after fractionated dosage of diazoxide (i.v.) as well as after dihydralazine (i.m.). The indication of acute parenteral therapy compared to less aggressive oral treatment is discussed.     

An integrative approach to CTL epitope prediction: a combined algorithm integrating MHC class I binding, TAP transport efficiency, and proteasomal cleavage predictions

Reverse immunogenetic approaches attempt to optimize the selection of candidate epitopes, and thus minimize the experimental effort needed to identify new epitopes. When predicting cytotoxic T cell epitopes, the main focus has been on the highly specific MHC class I binding event. Methods have also been developed for predicting the antigen-processing steps preceding MHC class I binding, including proteasomal cleavage and transporter associated with antigen processing (TAP) transport efficiency. Here, we use a dataset obtained from the SYFPEITHI database to show that a method integrating predictions of MHC class I binding affinity, TAP transport efficiency, and C-terminal proteasomal cleavage outperforms any of the individual methods. Using an independent evaluation dataset of HIV epitopes from the Los Alamos database, the validity of the integrated method is confirmed. The performance of the integrated method is found to be significantly higher than that of the two publicly available prediction methods BIMAS and SYFPEITHI. To identify 85% of the epitopes in the HIV dataset, 9% and 10% of all possible nonamers in the HIV proteins must be tested when using the BIMAS and SYFPEITHI methods, respectively, for the selection of candidate epitopes. This number is reduced to 7% when using the integrated method. In practical terms, this means that the experimental effort needed to identify an epitope in a hypothetical protein with 85% probability is reduced by 20-30% when using the integrated method.The method is available at http://www.cbs.dtu.dk/services/NetCTL. Supplementary material is available at http://www.cbs.dtu.dk/suppl/immunology/CTL.php.     

Carcinoembryonic antigen like antigen in granular cell myoblastomas

Summary A series of granular cell myoblastomas (GCM) and other benign and malignant tumours of soft tissue were examined for cytoplasmic content of carcinoembryonic antigen (CEA) by the two-layer conjugated immunoperoxidase technique. Using a commercial rabbit anti-CEA serum only granular cell myoblastomas showed positive cytoplasmic reaction. Pretreatment with periodic acid made this reaction less intense, but when the commercial rabbit anti-CEA serum was absorbed with tissue powder from normal human spleen the positive reaction was totally abolished. It is concluded that the positivity of GCM for CEA using commercial rabbit anti-CEA serum is due to the content of non-specific cross-reacting antigen (NCA) and maybe other cross-reacting glycoproteins in this tumour, and not to CEA as claimed in a previous study.     

Apical and basolateral expression of Aquaporin-1 in transfected MDCK and LLC-PK cells and functional evaluation of their transcellular osmotic water permeabilities

 Aquaporin-1 is present in the apical and basolateral membranes in proximal tubules and descending limbs of Henlé’s loop. In order to be able to study the routing of Aquaporin-1 and the regulation of Aquaporin-1-mediated transcellular water flow, we stably transfected LLC-PK₁ and MDCK-HRS cell lines with an Aquaporin-1 expression construct. LLC-PK₁ clone 7 and MDCK clone K integrated two and one copies, respectively, which was reflected in the amount of Aquaporin-1 mRNA expressed in both clones. The Aquaporin-1 protein levels, however, were similar. In both clones, immuno-electronmicroscopy showed extensive labelling of Aquaporin-1 on the basolateral plasma membrane, endosomal vesicles and the apical plasma membrane, including the microvilli. To measure transcellular water permeation, a simple method was applied using phenol-red as a cell-impermeant marker of concentration. In contrast to the native cell lines, both clones revealed a high transcellular osmotic water permeability, which could not be influenced by forskolin add/3-isobutyl-1-methylxanthine (IBMX) or the phorbol ester 12-O-tetradecanoyl 13-acetate (TPA). After glutaraldehyde fixation, it was inhibitable by HgCl₂. These results indicate that targeting of Aquaporin-1 to the apical and basolateral plasma membrane is independent of cell type and show for the first time that water flow through a cultured epithelium can be blocked by mercurial compounds. Received: 9 October 1996 / Received after revision: 3 January 1997 / Accepted: 8 January 1997