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Biomedical subjects

J Bondeson

Publications and source records attributed to J Bondeson.

67 records · Page 4Linked to original sources
PubMed1990

Promotion of acid-induced membrane fusion by basic peptides. Amino acid and phospholipid specificities.

The ability of oligo- and polymers of the basic amino acids L-lysine, L-arginine, L-histidine and L-ornithine to induce lipid intermixing and membrane fusion among vesicles containing various anionic phospholipids has been investigated. Among vesicle consisting of either phosphatidylinositol or mixtures of phosphatidic acid and phosphatidylethanolamine rapid and extensive lipid intermixing, but not complete fusion, was induced at neutral pH by poly-L-ornithine or L-lysine peptides of five or more residues. When phosphatidylcholine was included in the vesicles, the lipid intermixing was severely inhibited. Such lipid intermixing was also much less pronounced among phosphatidylserine vesicles. Poly-L-arginine provoked considerable leakage from the various anionic vesicles and caused significantly less lipid intermixing than L-lysine peptides at neutral pH. When the addition of basic amino acid polymer was followed by acidification to pH 5-6, vesicle fusion was induced. Fusion was more pronounced among vesicles containing phosphatidylserine or phosphatidic acid than among those containing phosphatidylinositol, and occurred also with vesicles whose composition resembles that of cellular membranes (i.e., phosphatidylcholine/phosphatidylethanolamine/phosphatidylserine, 50:30:20, by mol). Liposomes with this composition are resistant to fusion by Ca2+ or by acidification after lectin-mediated contact. The tight interaction among vesicles at neutral pH, resulting in lipid intermixing, does not seem to be necessary for the fusion occurring after acidification, but the basic peptides nevertheless appear to play a more active role in the fusion process than simply bringing the vesicles in contact. However, protonation of the polymer side chains and transformation of the polymer into a polycation does not explain the need for acidification, since the pH-dependence was quite similar for poly(L-histidine)- and poly(L-lysine)-mediated fusion.

Arginine↗
PubMed1989

Craniopagus parasiticus. Everard Home's Two-Headed Boy of Bengal and some other cases.

Craniopagus parasiticus, or épicome, is a rare teratological type, of which only six cases have been recorded in the medical literature. It differs from craniopagus conjoined twins in that the body and limbs of the parasitic twin are underdeveloped, leaving in some cases only a parasitic head, inserted on the crown of the autositic twin. The first case of this malformation was Everard Home's famous Twin-Headed Boy of Bengal, whose skull is preserved at the Hunterian Museum. In this historical review, Home's case is presented in some detail, and the later cases are used to explain further some of its particulars.

Abnormalities, Severe Teratoid↗
PubMed1987

Phosphatidylethanol counteracts calcium-induced membrane fusion but promotes proton-induced fusion.

The susceptibility of phosphatidylethanol-containing lipid vesicles towards Ca2+- and proton-induced fusion has been investigated, using a system of interacting vesicles. The results show that phosphatidylethanol-rich vesicles are quite resistant to Ca2+-induced fusion while being highly sensitive to proton-induced fusion. Inclusion of phosphatidylethanol was also found to promote and inhibit, respectively, the proton-induced and Ca2+-induced fusion of bilayer vesicles containing also phosphatidylethanolamine and either phosphatidylserine or phosphatidic acid. Thus, phosphatidylethanol affected Ca2+- and proton-induced fusion in opposite directions, in contrast to the naturally occurring anionic phospholipids phosphatidic acid, phosphatidylserine and phosphatidylinositol, which affect the sensitivity to Ca2+- and H+-induced fusion in the same direction. However, the fusion competence of phosphatidylethanol vesicles in response to both Ca2+ and H+ was inversely related to the apparent thickness of the polar headgroup layer, determined by using lectin-glycolipid interaction as a steric probe, as previously found for vesicles containing naturally occurring anionic phospholipids.

Agglutination↗
PubMed1984

Proton-induced membrane fusion. Role of phospholipid composition and protein-mediated intermembrane contact.

Glycolipid-phospholipid vesicles containing phosphatidate and phosphatidylethanolamine were found to undergo proton-induced fusion upon acidification of the suspending medium from pH 7.4 to pH 6.5 or lower, as determined by an assay for lipid intermixing based on fluorescence resonance energy transfer. Lectin-mediated contact between the vesicles was required for fusion. Incorporation of phosphatidylcholine in the vesicles inhibited proton-induced fusion. Vesicles in which phosphatidate was replaced by phosphatidylserine underwent fusion only when pH was reduced below 4.5, while no significant fusion occurred (pH greater than or equal to 3.5) when the anionic phospholipid was phosphatidylinositol. It is suggested that partial protonation of the polar headgroup of phosphatidate and phosphatidylserine, respectively, causes a sufficient reduction in the polarity and hydration of the vesicle surface to trigger fusion at sites of intermembrane contact.

Energy Metabolism↗
PubMedDate not supplied

Perianal abscess and sinuses caused by granuloma inguinale. Case report.

An atypical case of the venereal disease granuloma inguinale, which is very rare in Scandinavia, is reported. The patient presented with recurrent perianal abscess and sinuses, and the diagnosis was not made until histologic examination of an extirpated subcutaneous nodule showed cells containing the pathognomonic Donovan bodies.

Abscess↗
PubMedDate not supplied

Reversible scleroderma, fasciitis and perimyositis.

A patient with reversible scleroderma, fasciitis (without blood or tissue eosinophilia) and perimyositis is described. This case is of interest because it might be considered as an overlap between progressive systemic sclerosis and eosinophilic fasciitis.

Aged↗
PubMedDate not supplied

Polymyositis associated with asymptomatic primary biliary cirrhosis.

We here describe a case of polymyositis associated with asymptomatic primary biliary cirrhosis and a high titer of antimitochondrial antibodies. The patient had remarkable multiorgan engagement: polyarthritis, pericarditis, pleuritis and tachyarrythmia. Atypical changes, suggestive of mitochondrial damage, were observed in a muscle biopsy specimen. Under treatment with azathioprine and steroids, the disease had a favourable outcome.

Anti-Inflammatory Agents↗