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Biomedical subjects

R Persson

Publications and source records attributed to R Persson.

At least 37 records · Page 2Linked to original sources
PubMed1988

Labelling of proteins with [35S]methionine in monolayer cultures of rat hepatocytes.

Optimal conditions for the labelling of proteins with [35S]methionine in monolayers of rat hepatocytes have been established. The ability to incorporate the radioactive amino acid was constant for at least 26 h and independent of whether the medium was buffered with CO2/HCO3 or with 4-(2-hydroxyethyl)-1-piper-azineethanesulphonic acid (Hepes). Preincubation in methionine-free medium for up to 30 min yielded increasing, and from 60 to 180 min decreasing, rates of incorporation. An apparent Km value of 0.06 mM was obtained for the incorporation reaction in cells preincubated for 40 min.

Animals↗
PubMed1987

Differential permeabilization of membranes by saponin treatment of isolated rat hepatocytes. Release of secretory proteins.

Monolayer cultures of rat hepatocytes were treated with increasing concentrations of saponin (prepared from Gypsophila plants) for 30 min at 6 degrees C. Differential permeabilization of the intracellular membranes could be demonstrated: at 0.040 mg of saponin/ml the plasma membrane was permeabilized, as assessed by the release of 50% of the total cellular amount of lactate dehydrogenase, and at 0.20 mg/ml the endoplasmic reticulum was permeabilized, as measured by the release of 50% of pulse-35S-labelled albumin. The Golgi complex was permeabilized at an intermediate saponin concentration, as indicated by the release of homogeneously 35S-labelled albumin; about half the intracellular albumin is located in this organelle. At 1.0 up to 5.0 mg of saponin/ml 90-95% of the radioactively labelled albumin was released. Even at 5.0 mg/ml less than 10% of the membrane of the endoplasmic reticulum was solubilized, as judged by the degree of release of a membrane-bound enzyme specific for this organelle. These results demonstrate the usefulness of saponin as a tool for investigating the interior of different intracellular compartments.

Albumins↗
PubMed1985

Virus-receptor interaction in the adenovirus system: characterization of the positive cooperative binding of virions on HeLa cells.

The established positive cooperativity of adenovirus 2 binding to HeLa cells revealed a strong temperature dependence. The degree of cooperativity, quantified by means of Hill coefficients, progressively increased from 10 degrees C to reach a maximum level, which was maintained between 20 and 37 degrees C. On the other hand, negative cooperativity of virion attachment was apparent at 3.0 degrees C and on glutaraldehyde-stabilized cells. The corresponding monovalent ligand of the system, the fiber antigen, demonstrated only weak-positive cooperativity of the binding at 37.0 degrees C, which was absent at 3.0 degrees C. Dithiothreitol and dansylcadaverine, reagents inhibiting clustering of ligand-receptor complexes in the plasma membrane, markedly reduced the degree of positive cooperative binding at 37.0 degrees C. Evidently, the positive cooperative binding of adenovirus to HeLa cells at 37.0 degrees C is a consequence of both the multivalency of virus attachment proteins, i.e., fibers, on the virion and of the capacity of the receptor sites to migrate in the plane of the plasma membrane, forming local aggregates of virus-receptor site complexes.

Adenoviruses, Human↗
PubMed1984

Entry of adenovirus 2 into HeLa cells.

Adenovirus 2 (Ad2) uncoating was analyzed as the destabilization of virions which renders the parental genome sensitive to DNase treatment. This event demonstrated a strong temperature dependence, and an Arrhenius plot of initial uncoating rates revealed an inflection point at around 16 degrees C. Activation energies of 331 kJ/mol below and 88 kJ/mol above this temperature were obtained for the uncoating process. Penetration of Ad2 through the plasma membrane was completely inhibited by sodium azide, whereas uncoating was only slightly influenced. This indicated that uncoating had already taken place at the outside of the plasma membrane. Incubations of Ad2 with isolated plasma membranes and cell homogenates showed that intact and metabolizing cells were required for uncoating. We further suggest, based on the inhibitory patterns of EDTA, EGTA, dansylcadaverine, and dithiothreitol, that this destabilization of virions follows upon reorganization in the plasma membrane. In the electron microscope the involvement of coated vesicles was shown for the initial uptake of virions, possibly followed by the engagement of acidic vesicles as judged from the effects of lysosomotropic agents on gene expression. The vectorial transport of virions from the plasma membrane to the nucleus was not affected by reagents interfering with the cytoskeletal system. Consequently, we propose that Ad2 virions are internalized by adsorptive endocytosis.

Adenoviruses, Human↗
PubMed1983

Virus receptor interaction in the adenovirus system. II. Capping and cooperative binding of virions on HeLa cells.

Adenovirus type 2 attachment to HeLa cells was analyzed under controlled conditions. The temperature-dependent attachment kinetics revealed an inflection point at around 20 degrees C, and above this temperature the increase of the rate was doubled. In multiplicity dependence experiments, the attachment exhibited positive cooperative binding at 37 degrees C. This binding pattern was inhibited by low temperatures and prefixation of cells with 0.015% glutaraldehyde. Attachment of rhodamine-labeled virions revealed capping of the particles on 15% of the cells at 37 degrees C. Capping was inhibited by low temperatures, glutaraldehyde fixation of cells, and treatment with cytochalasin B, azide, and 2-deoxyglucose. Consequently, we propose that the adenovirus type 2 attachment to cells leads to rearrangements in the plasma membrane, resulting in cooperative binding and capping of the virus particles.

Adenoviruses, Human↗
PubMed1981

5-HT reuptake inhibitors plus tryptophan in endogenous depression.

In a previous double-blind, 3-week study we compared the effect of clomipramine + placebo with clomipramine + tryptophan in 24 patients with endogenous depression. The patients in the latter group showed a significantly more rapid improvement than those in the former group, especially with regard to the depression-anxiety cluster of symptoms. These results prompted us to perform a similar study in which zimelidine, a more specific inhibitor of 5-HT reuptake, was used instead of clomipramine. In other respects the design was practically identical to that used in the previous study. Unexpectedly, tryptophan in combination with zimelidine, was not superior to placebo + zimelidine with respect to antidepressant activity. In comparison with the previous study, the antidepressant action of zimelidine showed no statistically significant difference from clomipramine. However, the patients tended to show a more prompt response after zimelidine + placebo than after clomipramine + placebo. The changes in CSF metabolites were likewise different in the two studies. In the two studies taken together 12 out of 49 patients showed prompt improvement within one week. This raises the question whether the therapeutic response to antidepressant drugs necessarily involves a delay as is generally assumed. Side effects were remarkably few and mild in the second study.

Biogenic Amines↗
PubMed1981

Assessment of tooth mobility using small loads. III. Effect of periodontal treatment including a gingivectomy procedure.

The effect on tooth mobility of periodontal treatment utilizing a gingivectomy procedure was studied during a period of 26 weeks in 25 maxillary anterior teeth of six subjects with moderate to advanced periodontal disease. The gingival conditions were evaluated by gingival fluid measurement and the loss of marginal bone as seen on radiographs. Tooth mobility was measured in a bucco-lingual direction using forces between 20 p and 80 p. The results show a decrease of gingival fluid throughout the study. Tooth mobility was already reduced in the majority of teeth 2 weeks after surgery. An average reduction of tooth mobility amounting to 43.7% (using the corrective formula of Mühlemann 1960) was observed after 4 weeks. No additional reduction took place during the remaining experimental period.

Adult↗
PubMed1981

Assessment of tooth mobility using small loads. IV. The effect of periodontal treatment including gingivectomy and flap procedures.

Tooth mobility at loads below 100 p, gingival fluid amounts and bone score heights were studied in five subjects. In all 28 maxillary anterior teeth were investigated during a period of 68 weeks. In order to enlarge upon a previous investigation of tooth mobility following periodontal surgery (Persson 1980), the effects on tooth mobility of gingivectomy and flap procedures were compared. A split-mouth technique was used for the two surgical procedures which were performed during one session. No preoperative differences of the investigated parameters were found. During the first weeks after surgery, an increase of tooth mobility was seen which amounted to +80% maximum (flap side) and +13.1% (gingivectomy side). The final tooth mobility changes were -60% on the flap side and -40% on the gingivectomy side. No significant differences of tooth mobility were found between the two surgical methods. The present findings of tooth mobility following surgery also indicated a considerable time lapse before any major decrease of tooth mobility took place.

Adult↗
PubMed1981

Virus-receptor interaction in the adenovirus system I. Identification of virion attachment proteins of the HeLa cell plasma membrane.

Plasma membranes from HeLa cells were isolated in a two-phase polymer system. To compare the efficiency of attachment protein extraction, a normalized assay for the assessment of adenovirus type 2 (Ad2) receptor-active components interfering with the attachment of Ad2 to HeLa cells was developed. An optimized detergent extraction procedure, 0.5% Triton X-100, was used, and solubilized membrane proteins were radioisotope labeled in vitro. Proteins with affinity for Ad2 virions were quantified and identified in a sucrose gradient sedimentation assay and by affinity chromatography with cross-linked Ad2 virions immobilized to AH-Sepharose 4B. From virions recovered in the sucrose gradient system, one major membrane component of high affinity was identified with a polypeptide molecular weight of around 40,000. Glycosylated proteins isolated by wheat germ lectin chromatography with high affinity for immobilized virus particles were isolated, and two major components with apparent molecular weights of 40,000 and 42,000 were identified. We suggest that a glycosylated protein with high affinity for Ad2 virions and a polypeptide molecular weight of 40,000 to 42,000 is one component of the Ad2 attachment site on HeLa cells.

Adenoviruses, Human↗
PubMed1980

Assessment of tooth mobility using small loads. I. Technical devices and calculations of tooth mobility in periodontal health and disease.

An apparatus for recording tooth mobility of maxillary anterior teeth using loads below 100 p in a bucco-lingual direction is described. Strain gauges and a differential transformer are used as sensors of force and displacement. The displacement is recorded at the same location on the tooth surface and in the same direction as the loading force. Compressed air is used as the source of force. Documentation of signals is obtained by means of a two-channel potentiometric recorder. Tooth mobility was studied in six subjects with healthy periodontal conditions and in six subjects with moderate periodontal disease. Repeated measurements under standardized conditions demonstrated a satisfactory reproducibility of the measuring method. Tooth mobility curves within the 20-80 p loading range were transformed to lines of regression. Analysis of such lines seems to provide further information of tooth mobility qualities as compared to previous methods of tooth mobility measurements.

Dental Stress Analysis↗
PubMed1980

Assessment of tooth mobility using small loads. II. Effect of oral hygiene procedures.

Tooth mobility at loads between 20 p and 80 p was studied in maxillary incisors and canines in eight subjects with moderate periodontal disease. The periodontal conditions of the investigated teeth exhibited clinical criteria of gingival inflammation and a moderate loss of attachment. None of the subjects showed subjective or clinical signs of occlusal disturbances. In all, 35 teeth were investigated over the 12-week period following periodontal hygiene treatment, including oral hygiene instructions and removal of supra- and subgingival plaque and calculus. During the course of the investigation, a gradual decrease of tooth mobility was observed amounting to a tooth mobility decrease of 65% (using the corrective formula described by Mühlemann 1960) at 50 p load. Tooth mobility curves within the 20--80 p loading area were transformed to lines of regression (Persson & Svensson 1980). Analyses of the lines showed significantly lower tooth mobility values 12 weeks after start of treatment.

Adult↗
PubMed1979

On the relation between peripheral atherosclerosis and serum lipoproteins.

The occurrence and degree of peripheral atherosclerosis in 30 male patients with symptoms of intermittent claudication were studied by arteriography. The changes observed in the angiograms were codified. In all patients the concentrations of triglycerides and cholesterol were determined in whole serum and in the three major lipoprotein classes--very low density, low density and high density lipoproteins. These data were compared with those of a control material and were also correlated to the codified angiographic findings in each individual patient. Positive significant correlation was not found between the arteriographic changes and the serum concentrations of lipids and lipoproteins, which might be explained by an advanced stage of the disease where such relationships might not appear.

Adult↗