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D Persson

Publications and source records attributed to D Persson.

13 recordsLinked to original sources
PubMed2001

Penetratin-induced aggregation and subsequent dissociation of negatively charged phospholipid vesicles.

The interaction of the cellular delivery vector penetratin with a model system consisting of negatively charged phospholipid vesicles has been studied. Above a certain peptide to lipid molar ratio, the cationic oligopeptide induces vesicle aggregation. Interestingly, the aggregation is followed by spontaneous disaggregation, which may be related to membrane translocation of the peptide. Circular dichroism (CD) measurements indicate a conformational transition, from alpha-helix to antiparallel beta-pleated sheet, which is simultaneous with the aggregation process. The potential influence of spectroscopic artifacts on CD data due to the drastically increased turbidity during aggregation is discussed.

Carrier Proteins↗
PubMed2000

The antennapedia peptide penetratin translocates across lipid bilayers - the first direct observation.

The potential use of polypeptides and oligonucleotides for therapeutical purposes has been questioned because of their inherently poor cellular uptake. However, the 16-mer oligopeptide penetratin, derived from the homeodomain of Antennapedia, has been reported to enter cells readily via a non-endocytotic and receptor- and transporter-independent pathway, even when conjugated to large hydrophilic molecules. We here present the first study where penetratin is shown to traverse a pure lipid bilayer. The results support the idea that the uptake mechanism involves only the interaction of the peptide with the membrane lipids. Furthermore, we conclude that the translocation does not involve pore formation.

Animals↗
PubMed2000

Voiding pattern in healthy newborns.

A 4-hour observation period has been used in infants to investigate suspected bladder dysfunction. The aim of the present study was to extend the usefulness of this protocol by establishing reference values for voiding frequency, intervals, volumes, and residual urine in healthy newborns. The study included 51 healthy newborns, 26 girls and 25 boys, aged 3 to 14 days. During a 4-hour period, all micturitions and residuals were recorded as well as feeding, sleeping, crying, and defecations. The observation was completed with the child undressed to observe the urinary stream during one void. Different provocation tests were tried to induce urinary leakage. All newborns voided with a stream, about once per hour, with a median volume of 23 mL. For each voiding parameter, there was a large inter- and intra-individual variability. Double voidings were common as well as sizable residual volumes. The diuresis was about six times higher than in healthy school children. The healthy newborns did not leak during provocation tests such as manual compression of the bladder. Neurourol. Urodynam. 19:177-184, 2000.

Defecation↗
PubMed1998

Occupation and survival: a 25-year follow-up study of an aging population.

OBJECTIVE: In this retrospective study of an elderly population cohort living in a defined Swedish rural area, the relationship between occupation and survival as a measure of objective health was investigated. The cohort has been followed for 25 years. METHOD: On the basis of the baseline socioeconomic interview from assessments performed when the participants were 67 years of age, an index of active participation in daily occupation was devised. The index was used to investigate the covariation between generic everyday occupation and long-time survival. RESULTS: For the female participants, Kaplan-Meier curves demonstrated differences in survival between the "less active" and "more active," and Cox regression survival analyses resulted in a significant covariance between occupation and survival. For the male participants, no such differences were found. CONCLUSION: The significant results for the women implied support for the core assumption of occupational therapy that a relationship exists between occupation and health. The lack of differences in survival among more active and less active men demonstrates the complexity of studying occupation.

Activities of Daily Living↗
PubMed1993

The elderly driver: deciding when to stop.

This study examines the decision of people (N = 56) living in retirement communities to quit driving, and the role of their physician and family in making this decision. Most of the elderly stopped driving when a threshold was reached after an accumulation of compensatory behaviors. Few stopped because of their doctor's advice, although all felt a physician was in the best position to evaluate driving, and family involvement received limited support.

Aged↗
PubMed1984

The condensation of DNA by chromium (III) ions.

Cr(III), one of the most potent inorganic carcinogens, induces condensation of DNA into a very compact product at 37 degrees, as shown by electron microscopy. The condensation begins with the appearing of some supercoil structures and complete condensation occurs at relatively low Cr(III) concentrations; for 3 and 30 mM ionic strength they are 4.5 and 45 microM, respectively. Under these conditions, Cr(III) inhibits the interaction between ethidium and DNA as shown by absorption and fluorescence spectra.

Chromium↗
PubMed1979

Copper(I) complexes of penicillamine and glutathione.

Equilibrium analysis of a model system for the in vivo reactions between penicillamine and Cu(I), the penicillamine-glutathione-Cu(I) system, indicates that in a certain concentration range the use of penicillamine as a drug will not disturb the normal Cu(I) metabolism. The equilibrium data required for this analysis were obtained by emf titrations on the Cu(I)-glutathione (H3A) and the Cu(I)-pencillamine (H2A) systems at 25 degrees C. in 0.5 M NaClO4 medium, using glass and copper amalgam electrodes; the data were analyzed first by various graphical methods and then by a general least squares computer program. The results show that mononuclear Cu(I) species Cu(HA)2 form in both systems with stability constants log beta 122 of 38.8 (glutathione) and 39.18 (penicillamine); in addition, the polynuclear Cu5A43- species forms in the penicillamine system and the mononuclear CuHA- species might form in the glutathione system. The results are discussed in relation to the therapeutic use of penicillamine as well as in relation to the toxic action of copper on living cells.

Chemical Phenomena↗