PubMed Health⌕ Search

Biomedical subjects

B Wåhlin

Publications and source records attributed to B Wåhlin.

At least 19 recordsLinked to original sources
PubMed1997

Ribavirin therapy in bone marrow transplant recipients with viral respiratory tract infections.

Treatment with ribavirin was instituted in 12 allogeneic and one autologous bone marrow transplant (BMT) recipients with proven respiratory syncytial virus (RSV), influenza B virus or parainfluenza virus infections. RSV was diagnosed in six cases, influenza B virus in four and parainfluenza virus in three patients. Ribavirin was given orally or intravenously (15-20 mg/kg/day in three divided doses) and in nine cases with the addition of ribavirin inhalations (6 g/day). Three patients required ventilator support. Three out of seven patients with pneumonia, including one patient with RSV who developed pulmonary infiltrates 10 days after the start of therapy, died despite treatment with ribavirin (two RSV, one influenza B). Multiple etiological agents were found in the fatal cases. The clinical condition improved in 10 of 13 patients during therapy. No serious adverse effects of systemic ribavirin were noticed. Two patients had reversible signs of hemolysis but only one patients required more erythrocyte transfusions than expected after BMT. Obstructive respiratory distress was often observed (6/9 patients receiving ribavirin inhalation therapy), which resulted in discontinuation of aerosolized therapy in four cases. Time to engraftment (WBC < 0.2 x 10(9)/l) did not differ from other non-treated BMT patients. We conclude that ribavirin is well tolerated both orally and intravenously and it may, if instituted before development of hypoxia, reduce morbidity and mortality of RSV, influenza B and parainfluenza in this group of patients.

Administration, Oral↗
PubMed1996

A paediatric canopy system for aerosol administration and minimized environmental pollution.

BACKGROUND: A canopy system for ribavirin aerosol administration to infants has been developed in order to improve the control of aerosol treatment, facilitate access to the infant and minimize environmental pollution. The system comprises a transparent canopy, fitted with four sealable apertures. An evacuation flow that is 3 l/min higher than the gas supply was anticipated to prevent aerosol leakage from the canopy. METHOD: In a clinical evaluation, 10 infants with body weights of 1.8-7.1 kg were placed inside the canopy during 1 hour of simulated treatment. The temperature, relative humidity and carbon dioxide concentration within the canopy were measured repeatedly to study the stability of these variables and their dependence on body weight. Infant body temperature, skin temperature and the respiratory frequency were measured. In a laboratory evaluation, aerosol leakage was studied using an ambient air admixture procedure and smoke tests. The sound level inside the canopy was measured. RESULTS: All physical variables inside the canopy remained stable. The sound level was 52 dBA. The carbon dioxide concentration (1000-3900 PPM) correlated with infant body weight (P < 0.001), as did canopy temperature (25.1-29.6 degrees C, P < 0.05). The relative humidity was 52-88%. Infant body temperatures were not influenced. The respiratory frequency decreased by 13% (P < 0.01). No aerosol leakage was observed. CONCLUSION: The canopy system facilitates a controlled aerosol therapy with good infant surveillance and accessibility a minimum of environmental pollution and a comfortable physical environment without apparent risks of carbon dioxide rebreathing or cooling stress at body weights of 1.8-7.1 kg.

Administration, Inhalation↗
PubMed1993

Plasmodium falciparum: the immune response in rabbits to the clustered asparagine-rich protein (CARP) after immunization in Freund's adjuvant or immunostimulating complexes (ISCOMs).

The Plasmodium falciparum clustered asparagine-rich protein (CARP) is a merozoite-associated antigen which contains approximately 30% asparagine. Analysis of the DNA sequences located 5' of the cloned 1.4-kb CARP gene in the P. falciparum genome suggests that this gene fragment may encode the complete CARP and that the gene product is a protein of M(r) 50,000. To analyze the immunogenicity of CARP, the gene was expressed as a fusion protein with staphylococcal protein A (SpA-CARP). Immunization of rabbits with SpA-CARP in Freund's complete adjuvant (FCA) resulted in a strong antibody response against CARP as measured in ELISA. This response was efficiently boosted and sustained over a long time while that induced by two immunizations with SpA-CARP in ISCOMs was weak and of shorter duration. In both instances, the antibody levels against CARP were further increased by a second booster injection consisting of either SpA-CARP or CARP fused to the serum albumin-binding region (BB) of streptococcal protein G (BB-CARP) in PBS, indicating that immunizations with SpA-CARP in FCA or ISCOMs had induced a CARP-specific immunological memory. Boosting with BB-CARP in PBS was more efficient than boosting with SpA-CARP in PBS. In all rabbits, the antibodies obtained after the booster with CARP in PBS were the most efficient inhibitors of merozoite invasion in vitro. The antisera reacted with the intracellular parasite in immunofluorescence and with a band of M(r) 50,000 in immunoblotting while several high-molecular-weight components as well as the one of M(r) 50,000 were immunoprecipitated. The specificity of the antibody responses varied between the different rabbits as indicated in ELISA, with short synthetic peptides representing different CARP sequences. Taken together, the results suggest that a previously cloned genomic DNA fragment may encode the complete P. falciparum blood-stage antigen CARP and that CARP is immunogenic in rabbits both when administered in FCA or ISCOMs.

Amino Acid Sequence↗
PubMed1993

Immunogenicity in rabbits and monkeys of influenza ISCOMs conjugated with repeated sequences of the Plasmodium falciparum antigen Pf155/RESA.

Rabbits and monkeys were immunized with two fusion proteins, ZZ-M3 and ZZ-M5, coupled to pre-formed influenza virus membrane glycoprotein ISCOMs. The fusion proteins comprise two IgG-binding domains from staphylococcal protein A (ZZ) and repeated amino acid sequences from the C-terminal (M3) or central (M5) repeat regions of the Plasmodium falciparum antigen Pf155/RESA. The induced antibody responses were of long duration, could be efficiently boosted and were comparable to those obtained with Freund's Adjuvant. The produced antibodies reacted with M3, M5, protein A and the influenza glycoprotein, recognized Pf155/RESA and inhibited merozoite invasion in vitro. These results suggest that coupling of immunogens to pre-formed ISCOMs may be a basis for construction of multivalent subunit vaccines.

Amino Acid Sequence↗
PubMed1992

Shortened cecropin A-melittin hybrids. Significant size reduction retains potent antibiotic activity.

We have earlier reported two 26-residue antibacterial peptides made up from different segments of cecropin A (CA) and melittin (M). We now report a substantial reduction in size at the C-terminal section of the highly active hybrid CA(1-8)M(1-18), leading to a series of 20-, 18- and 15-residue analogs with antibiotic properties similar to the larger molecule. In particular, the 15-residue hybrids CA(1-7)M(2-9), CA(1-7)M(4-11) and CA(1-7)M(5-12) are the shortest cecropin-based peptide antibiotics described so far, with antibacterial activity and spectra similar or better than cecropin A and a 60% reduction in size. Their reduced size and highly alpha-helical structure require an alternative mechanism for their interaction with bacterial membranes.

Amino Acid Sequence↗
PubMed1992

Involvement of Pf155/RESA and cross-reactive antigens in Plasmodium falciparum merozoite invasion in vitro.

Lines of Plasmodium falciparum FCR3 either expressing or not expressing the blood-stage antigen Pf155/RESA were used to analyze the possible involvement of this antigen in the merozoite invasion process in vitro. Antibodies from human sera, affinity purified on synthetic peptides corresponding to C-terminal repeated sequences in Pf155/RESA, were shown to inhibit merozoite invasion of both types of parasites with similar efficiency. Reversal of the invasion inhibition by fusion proteins containing repeated sequences of Pf155/RESA but not of the cross-reactive antigens Ag332 and Pf11.1 indicated that the inhibitory antibodies had similar target antigens in both Pf155/RESA+ and Pf155/RESA- parasites that involved cross-reacting epitopes present in Pf155/RESA. Rabbit antibodies specific for Pf155/RESA repeats inhibited merozoite invasion of Pf155/RESA expressing parasites efficiently but had no or very small effect on the invasion of Pf155/RESA-deficient parasites. In contrast, rabbit antibodies specific for Ag332 repeats as well as human antibodies affinity purified on synthetic Ag332 peptides inhibited merozoite invasion of both types of parasites with high efficiency. A similar inhibition pattern was seen with the human monoclonal antibody 33G2, which has specificity for Ag332 but also cross-reacts with Pf155/RESA and Pf11.1. Taken together, our data suggest that Pf155/RESA and related cross-reactive antigens as well as Ag332 are involved in the merozoite invasion process and may constitute targets for invasion inhibitory antibodies.

Animals↗
PubMed1991

Plasmodium falciparum: an invasion inhibitory human monoclonal antibody is directed against a malarial glycolipid antigen.

A Plasmodium falciparum malaria blood stage antigen was detected using a human monoclonal antibody (MAb A52A6) obtained from a clinically immune donor. Immunofluorescence analysis showed that the MAb reacted with the intracellular parasite throughout the asexual blood stage cycle as well as with gametocytes. The MAb also reacted with the surface of erythrocytes containing late stage P. falciparum parasites. The antigen seen by the MAb was species- but not strain- or isolate-specific. At rupture of the infected erythrocytes, antigenic material was deposited on the membrane of uninfected cells surrounding the parasite. At merozoite invasion MAb reactive material was present on the invaginating erythrocyte membrane, indicating an involvement of the antigen in the invasion process. This was also indicated by the high capacity of the MAb to inhibit merozoite invasion in vitro. The antigen appears to be a phosphoglycolipid, sensitive to phospholipase and present in lipid extracts of P. falciparum-infected erythrocytes.

Animals↗
PubMed1991

High antibody responses in rabbits immunized with influenza virus ISCOMs containing a repeated sequence of the Plasmodium falciparum antigen Pf155/RESA.

Immunostimulating complexes (ISCOMs) are spherical structures where immunogens are presented as multimers in a matrix of the adjuvant Quil A. ISCOMs have been shown to enhance the immunogenicity of several antigens important to both human and veterinary vaccine development. We have coupled a fusion protein, designated ZZ-M2, comprising eight copies of the C-terminal repeat subunit EENV of the Plasmodium falciparum blood-stage antigen Pf155/RESA and two IgG-binding domains of staphylococcal protein A (SpA), to preformed influenza virus envelope protein ISCOMs. Rabbits immunized with the conjugated ISCOMs produced high titres of antibodies even after the first injection. These antibodies reacted with the EENV repeat sequence in ELISA and with Pf155/RESA in immunofluorescence on infected erythrocytes. The antibody response, which was sustained for more than 20 weeks, was efficiently boosted and superior or equal to that obtained after immunization with ZZ-M2 in Freund's complete adjuvant. In contrast, the antibody response induced in rabbits immunized with ZZ-M2 in Syntex Adjuvant Formulation-MF (SAF-MF) was weak and of short duration. The antibodies produced after immunization with ZZ-M2 coupled to influenza virus ISCOMs mainly recognized epitopes formed by two or more EENV subunits and were highly specific for Pf155/RESA. Furthermore, the antibodies efficiently inhibited merozoite reinvasion of erythrocytes in vitro, indicating that they recognized epitopes exposed on the native antigen. In addition, the ZZ-M2-conjugated ISCOMs also induced high titres of antibodies reacting with SpA or the influenza virus envelope protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Adjuvants, Immunologic↗
PubMed1991

Passive immunization of Aotus monkeys with human antibodies to the Plasmodium falciparum antigen Pf155/RESA.

In order to assess the protective effects of anti-Pf155/RESA antibodies of different specificities in vivo, passive immunizations of Aotus monkeys were performed. Antibodies reactive with the Pf155/RESA repeat sequences (EENV)2 and EENVEHDA were isolated from the immunoglobulin G (IgG) fraction of a pool of plasmas from Liberia by affinity chromatography on synthetic peptides. The two fractions of antibodies differed in specificity but displayed similar capacities to inhibit merozoite invasion in Plasmodium falciparum in vitro cultures. Four groups of monkeys (named groups I to IV) were injected with (i) 160 mg of total control IgG, (ii) 2 mg of IgG affinity purified on (EENV)2, (iii) 2 mg of IgG affinity purified on EENVEHDA, and (iv) 160 mg of total immune IgG, respectively. The monkeys were then challenged with P. falciparum-infected erythrocytes, and the levels of parasitemia and hematocrits as well as other serological parameters were determined daily. Although all groups developed parasitemia, groups II and IV tended to show lower mean daily levels. Three monkeys of group II and two monkeys (each) of groups III and IV self cured the infections, but so did one monkey from the group treated with control IgG (group I). The serum levels of transfused antibodies were low at the peak of parasitemia, suggesting that clearance of parasites was mediated by immune responses mounted by the monkeys. The results indicate that antibodies to epitopes formed by repeats of Pf155/RESA may depress P. falciparum parasitemias and thus that immunogens based on such repeats should be suitable components in a subunit vaccine against asexual stages of P. falciparum.

Adult↗
PubMed1990

Plasmodium falciparum: differential parasite reactivity of rabbit antibodies to repeated sequences in the antigen Pf155/RESA.

For selection of immunogens capable of inducing high levels of antibodies reactive with the Plasmodium falciparum antigen Pf155/RESA, rabbits were immunized with synthetic peptides corresponding to sequences based on the repeat subunits EENVEHDA and (EENV)2 from the C-terminus of this antigen. The antibodies obtained were analyzed with regard to binding to synthetic peptides in ELISA and to reactivity with parasite antigens by immunofluorescence or immunoblotting. All antisera reacted with both the peptides EENVEHDA and (EENV)2 as well as with Pf155/RESA. Antibody fractions specific for each of the two peptides were prepared by affinity chromatography on insolubilized peptides. Strong reactivity with antigens in the membrane of erythrocytes infected with early stages of the parasite as well as reactivity with Pf155/RESA in immunoblotting correlated with reactivity of antibody with (EENV)2. Antibody preparations reactive with EENVEHDA and depleted of (EENV)2 reactivity showed only a weak reactivity with Pf155/RESA but reacted also with P. falciparum polypeptides of 250, 210, and 88 kDa. In immunofluorescence, these antibodies stained mainly the intraerythrocytic parasite. Both EENVEHDA- and (EENV)2-specific antibodies inhibited merozoite reinvasion in P. falciparum in vitro cultures, the latter antibodies being the most efficient. This study defines the specificity and cross-reactivity with other P. falciparum antigens of antibodies to the C-terminal repeats of Pf155/RESA.

Amino Acid Sequence↗
PubMed1990

All-D amino acid-containing channel-forming antibiotic peptides.

The D enantiomers of three naturally occurring antibiotics--cecropin A, magainin 2 amide, and melittin--were synthesized. In addition, the D enantiomers of two synthetic chimeric cecropin-melittin hybrid peptides were prepared. Each D isomer was shown by circular dichroism to be a mirror image of the corresponding L isomer in several solvent mixtures. In 20% hexafluoro-2-propanol the peptides contained 43-75% alpha-helix. The all-D peptides were resistant to enzymatic degradation. The peptides produced single-channel conductances in planar lipid bilayers, and the D and L enantiomers caused equivalent amounts of electrical conductivity. All of the peptides were potent antibacterial agents against representative Gram-negative and Gram-positive species. The D and L enantiomers of each peptide pair were equally active, within experimental error. Sheep erythrocytes were lysed by both D- and L-melittin but not by either isomer of cecropin A, magainin 2 amide, or the hybrids cecropin A-(1-13)-melittin-(1-13)-NH2 or cecropin A-(1-8)-melittin-(1-18)-NH2. The infectivity of the bloodstream form of the malaria parasite Plasmodium falciparum was also inhibited by the D and L hybrids. It is suggested that the mode of action of these peptides on the membranes of bacteria, erythrocytes, plasmodia, and artificial lipid bilayers may be similar and involves the formation of ion-channel pores spanning the membranes, but without specific interaction with chiral receptors or enzymes.

Amino Acid Sequence↗
PubMed1990

Immunogenicity and antigenicity in rabbits of a repeated sequence of Plasmodium falciparum antigen Pf155/RESA fused to two immunoglobulin G-binding domains of staphylococcal protein A.

A synthetic gene encoding a tetramer of the repeated subunit EENVEHDA of the Plasmodium falciparum antigen Pf155/RESA was expressed in a dual-expression system. The resulting fusion proteins, designated ZZ-M1 and BB-M1, comprised the EENVEHDA repeats and either two immunoglobulin G-binding domains from staphylococcal protein A or the human serum albumin-binding domains from streptococcal protein G, respectively. The soluble fusion proteins were affinity purified to homogeneity in one-step procedures. ZZ-M1 was used for immunization of rabbits. The rabbit antisera reacted with BB-M1 in an enzyme-linked immunosorbent assay and with Pf155/RESA in immunofluorescence of infected erythrocytes and immunoblotting. Inhibition studies revealed that the antibodies mainly recognized epitopes formed by two or more EENVEHDA subunits and were remarkably specific for Pf155/RESA. Importantly, the antibodies also inhibited P. falciparum merozoite reinvasion in vitro efficiently, indicating that they reacted with biologically important epitopes exposed on the native antigen. Immunization with Freund complete adjuvant resulted in high levels of specific immunoglobulin G antibodies over a 1-year period, whereas the antibody response obtained after immunization without adjuvant was generally weaker, immunoglobulin G and M mediated, and not sustained for longer periods. However, these titers were restored after booster injection. Taken together, the results support the usefulness of recombinant gene constructs of this type as immunogens for malaria vaccines.

Amino Acid Sequence↗
PubMed1990

Anti-idiotypic antibodies counteract the invasion inhibition capacity of antibodies to major epitopes of the Plasmodium falciparum antigen Pf155/RESA.

Rabbits were immunized with the synthetic peptide EENVEHDA or (EENV)2, corresponding to a tandemly repeated sequence in the C-terminal part of the Plasmodium falciparum antigen Pf155/RESA, or with Escherichia coli-derived fusion proteins containing the corresponding repeats. For all sera, the capacity of the total immunoglobulin G fractions to inhibit P. falciparum merozoite invasion in vitro was similar and relatively low. Affinity purification of Pf155/RESA-specific antibodies on parasite-infected erythrocyte monolayers or on peptide columns increased the inhibitory capacity 50 to 5,000 times, whereas the immunofluorescence titers were increased only 10 times. The addition of small amounts of total immunoglobulin G to the affinity-purified antibodies gave a marked and dose-dependent reduction of the inhibitory capacity of the purified antibodies. However, this reduction was only seen in combinations where the immunoglobulin G fraction was from the same serum as the affinity-purified antibodies, suggesting that it was mediated by anti-idiotypic antibodies reacting with non-cross-reacting idiotopes of the invasion-inhibiting antibodies.

Amino Acid Sequence↗
PubMed1990

The active fitting (AF) programme of hearing aids: a psychological perspective.

Rehabilitation of the majority of hearing handicapped in Sweden consists of hearing aid fitting, provision of technical devices and information during about four visits to a Hearing Centre. Generally there is no structured guidance of the hearing handicapped on how to proceed with the hearing aid at home between appointments. A programme of active fitting (AF) of hearing aids, with a task-oriented diary, 'Try Your Hearing Aid' as a basic part, was therefore developed. We conducted a series of studies from 1985 to 1988 with the aim of investigating the benefit and applicability of the programme. A total of 128 new hearing aid candidates participated in three studies at the Sahlgrens hospital and at four other hearing centres in smaller Swedish towns. In a controlled study the AF group was more positive to their hearing aids and to the fitting period after 10 months. They used their hearing aids more frequently and felt psychologically more secure with them. It was established that the AF programme could well be applied in the clinical routine for a majority of new hearing aid patients. Old age per se was not found to be a relevant exclusion criterion. The positive outcome of the AF programme has stimulated the Swedish Institute of the Handicapped to print 'Try Your Hearing Aid' with a manual, and to introduce it to all hearing centres in Sweden.

Aged↗
PubMed1989

Antibacterial and antimalarial properties of peptides that are cecropin-melittin hybrids.

Solid phase synthesis was used to produce 5 hybrid peptides containing sequences from the antibacterial peptide, cecropin A, and from the bee venom toxin, melittin. Four of these chimeric peptides showed good antibacterial activity against representative Gram-negative and Gram-positive bacterial species. The best hybrid, cecropin A(1-13)-melittin(1-13) was 100-fold more active than cecropin A against Staphylococcus aureus. It was also a 10-fold better antimalarial agent than cecropin B or magainin 2. Sheep red cells were lysed by melittin at low concentrations, but not by the hybrid molecules, even at 50 times higher concentrations.

Amino Acid Sequence↗
PubMed1989

Reactivity of the human monoclonal antibody 33G2 with repeated sequences of three distinct Plasmodium falciparum antigens.

The human mAb 33G2 has high capacity to inhibit in vitro invasion of erythrocytes by Plasmodium falciparum merozoites and, thus, is of special interest with regard to protective immunity against the parasite. In order to obtain more information about asexual blood stage Ag of P. falciparum that are seen by this antibody, material from synchronized P. falciparum cultures was studied by immunofluorescence, immunoelectron microscopy, and immunoblotting. Reactivity was mainly confined to the membrane of infected erythrocytes. Soon after merozoite invasion the antibody stained the erythrocyte membrane. This membrane-associated staining faded during intracellular development of the parasites. Beginning about 18 h after invasion, a dotted pattern appeared which increased in strength with time and persisted to schizont rupture. Pf155/RESA was the major Ag recognized in immunoblots of parasites collected throughout the entire erythrocytic cycle, although other polypeptides also bound the antibody. Among these was a 260-kDa polypeptide found in late trophozoites and schizonts. The specificity of the antibody was analyzed with synthetic peptides corresponding to repeated sequences in the P. falciparum Ag Pf155/RESA, Pf11.1, and Ag332. Synthetic peptides related to Ag332 were the most efficient inhibitors of antibody binding in immunofluorescence studies and cell ELISA. A beta-galactosidase-Ag332 fusion protein was also efficient in reversing reinvasion inhibition caused by 33G2. These results define a family of cross-reactive P. falciparum Ag recognized by mAb 33G2 and suggest that Ag332 was its original target.

Amino Acid Sequence↗
PubMed1989

Plasmodium falciparum-infected erythrocytes form spontaneous erythrocyte rosettes.

Erythrocytes infected with trophozoites or schizonts of Plasmodium falciparum bind uninfected erythrocytes, leading to rosette formation. Both established laboratory strains and fresh isolates from patients form such rosettes, but at widely different frequencies. IgG preparations from the serum of some P. falciparum-immune donors and heparin inhibited rosette formation. The results indicate that cytoadherence of infected erythrocytes to endothelial cells and rosetting represent distinct genetic traits.

Animals↗