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Biomedical subjects

P Stenberg

Publications and source records attributed to P Stenberg.

At least 37 records · Page 2Linked to original sources
PubMed1998

Synthesis of basic fibroblast growth factor by murine mast cells. Regulation by transforming growth factor beta, tumor necrosis factor alpha, and stem cell factor.

BACKGROUND: Mast cells (MC) are involved in a wide spectrum of disorders characterized by neovascularization and fibroproliferation. We and others recently reported that human MC are a source of basic fibroblast growth factor (b FGF-2), a potent angiogenic and mitogenic polypeptide, in several disease conditions, such as chronic inflammation, hemangioma, and benign cutaneous mastocytosis. These findings suggest that FGF-2 may be an important mediator of cell proliferation and angiogenesis associated with MC. Since MC are heterogeneous across species, it is unknown whether FGF-2 expression is a feature common to all MC, or whether FGF-2 expression by MC can be regulated. We therefore examined FGF-2 expression by MC in mouse tissue and MC lines. METHODS: Immunostaining, RT-PCR, ELISA, immunoblot and Northern blot analyses were employed to study four murine MC lines for FGF-2 expression and its regulation by transforming growth factor-beta (TGF-beta), stem cell factor (SCF), and tumor necrosis factor-alpha (TNF-alpha). RESULTS: Mouse tissue MC and three of four murine MC lines (CFTL-12, CFTL-15, ABFTL-3) express FGF-2 as judged by immunostaining, ELISA, Western blot and Northern blot analyses, and reverse transcription-polymerase chain reaction. While TNF-alpha appeared to downregulate FGF-2 mRNA levels, treatment with SCF or TGF-beta resulted in an increase in the expression of FGF-2 at mRNA level which can be attenuated by TNF-alpha. However, the concurrent increase in FGF-2 protein was negligible, possibly due to immaturity of these cell lines. CONCLUSION: Expression of FGF-2 may be a ubiquitous feature of MC in other species in addition to humans, and can be selectively regulated by SCF, TGF-beta and TNF-alpha.

Animals↗
PubMed1997

Polar molecular surface properties predict the intestinal absorption of drugs in humans.

PURPOSE: A theoretical method has been devised for prediction of drug absorption after oral administration to humans. METHODS: Twenty structurally diverse model drugs, ranging from 0.3 to 100% absorbed, were investigated. The compounds also displayed diversity in physicochemical properties such as lipophilicity, hydrogen bonding potential and molecular size. The dynamic molecular surface properties of the compounds were calculated, taking into account their three-dimensional shape and flexibility. RESULTS: An excellent sigmoidal relationship was established between the absorbed fraction after oral administration to humans (FA) and the dynamic polar molecular surface area (PSAd) (r2 = 0.94). The relationship was stronger than those obtained for more established predictors of drug absorption. Drugs that are completely absorbed (FA > 90%) had a PSAd < or = 60 A2 while drugs that are < 10% absorbed had a PSAd > or = 140 A2. CONCLUSIONS: The results indicate that PSAd can be used to differentiate poorly absorbed drugs at an early stage of the drug discovery process.

Chemical Phenomena↗
PubMed1996

Response of LAI-2000 estimates to changes in plant surface area index in a Scots pine stand.

We assessed the accuracy with which the LAI-2000 plant canopy analyzer measured changes in leaf area index (LAI) and plant area index (PAI) in a 25-year-old Scots pine (Pinus sylvestris L.) stand. Stand density was 2100 stems ha(-1) and mean tree height was 8.7 m. Needle and branch areas of the stand were reduced progressively to zero by the stepwise removal of branches on all trees growing in a circular plot with a radius of 25 m. An LAI-2000 estimate was taken after each step reduction. The needle and branch surface areas removed at each step were estimated from direct measurements and were compared with the changes in the LAI-2000 estimates. Initially (before removal of branches), directly measured PAI was 5.2 (needles = 86%, branches = 8% and stems = 6%). The LAI-2000 estimate of total surface area was 66% of direct PAI and 77% of direct LAI. There was a nonlinear relationship between the LAI-2000 estimate and directly measured PAI, such that their ratio (equivalent to the clumping factor) increased from 0.66 to 1.05 with decreasing PAI. At the last measurement, when only stems were left, the LAI-2000 estimate agreed well with the direct measurement of PAI. The LAI-2000 underestimated the direct measurement of LAI at the first three steps when LAI was > 2 and the proportion of woody area was small (< 20%). However, because the LAI-2000 estimate included stem and branch areas, it overestimated the direct measurement of LAI at the last three measurements when the proportion of woody area was large (> 20%).

Journal Article↗
PubMed1995

Variation in the ratio of shoot silhouette area to needle area in fertilized and unfertilized Norway spruce trees.

We compared the range and variation in shoot silhouette area to projected leaf area ratio (SPAR) in fertilized and unfertilized (control) Norway spruce (Picea abies (L.) Karst.) trees. We measured SPAR for several view directions of 169 shoots at different depths in the crown of fertilized and control trees. There was an increase in SPAR with depth in the crown in both control and fertilized trees. In the fertilized trees, however, mean SPAR was larger overall, the increase with depth in the crown was steeper, and there was a larger variation in SPAR with inclination and rotation angle of the shoot (relative to the view direction). In particular, shoots in the lower crown of fertilized trees were rotationally asymmetrical ("flat") and had high values of the maximum ratio of shoot silhouette area to projected leaf area (SPAR(max)). Differences in SPAR between fertilized and control trees were explained by changes in shoot structure in response to fertilization and shading. Shoots of fertilized trees were larger and had more needle area than shoots of control trees. However, the ratio of needle area to shoot size was smaller in fertilized trees than in control trees, implying less within-shoot shading and, consequently, a larger SPAR. Also, the increase in SPAR with increased shading (depth in the crown) could be explained by a decrease in the ratio of needle area to shoot size. In addition, because fertilized trees had more needle area than control trees, the effect of shading at a given depth in the crown was more pronounced in fertilized trees than in control trees.

Journal Article↗
PubMed1994

Roles of pilin and PilC in adhesion of Neisseria meningitidis to human epithelial and endothelial cells.

Pili and pilin antigenic variation play important roles in adhesion of Neisseria meningitidis (MC) to human epithelial and endothelial cells. We recently identified one pilin variant that confers high adhesiveness of MC to human epithelial cells in culture. However, other factor(s) also play a role in MC adhesiveness, since some nonadhesive variants of MC strain 8013 are piliated and produce the same pilin variant as adhesive derivatives. PilC1 and PilC2, high molecular weight outer membrane proteins in Neisseria gonorrhoeae, are proposed to play roles in pilus assembly. Strain 8013 also contains pilC1 and pilC2; their products function in a similar if not identical manner in pilus biogenesis. PilC1 has an additional function in that it also modulates adhesiveness of strain 8013.

Bacterial Adhesion↗
PubMed1993

Antigenic variation of pilin regulates adhesion of Neisseria meningitidis to human epithelial cells.

Pili have been shown to play an essential role in the adhesion of Neisseria meningitidis to epithelial cells. However, among piliated strains, both inter- and intrastrain variability exist with respect to their degree of adhesion to epithelial cells in vitro (Virji et al., 1992). This suggests that factors other than the presence of pili per se are involved in this process. The N. meningitidis pilin subunit undergoes extensive antigenic variation. Piliated low- and high-adhesive derivatives of the same N. meningitidis strain were selected and the nucleotide sequence of the pilin gene expressed in each was determined. The highly adhesive derivatives had the same pilin sequence. The alleles encoding the pilin subunit of the low-adhesive derivatives were completely different from the one found in the high-adhesive isolates. Using polyclonal antibodies raised against one hyperadhesive variant, it was confirmed that the low-adhesive piliated derivatives expressed pilin variants antigenically different from the highly adhesive strains. The role of antigenic variation in the adhesive process of N. meningitidis was confirmed by performing allelic exchanges of the pilE locus between low- and high-adhesive isolates. Antigenic variation has been considered a means by which virulent bacteria evade the host immune system. This work provides genetic proof that a bacterial pathogen, N. meningitidis, can use antigenic variation to modulate their degree of virulence.

Amino Acid Sequence↗
PubMed1992

A reversed activity staining procedure for detection of an acquired antibody against factor XIII in a girl with factor XIII deficiency.

A new method for detection of inhibitors against factor XIII is described. Agarose gel electrophoresis with normal platelet poor plasma as a factor XIII source included in the gel was combined with reversed activity staining. The procedure was applied to a 10-year-old girl with factor XIII deficiency where substitution therapy had failed. Plasma samples from the patient inhibited the factor XIII catalysed incorporation of the fluorescent monodansylthiacadaverine into casein at a position corresponding to the migration of gamma-globulins. Treatment with Sepharose-bound protein A effectively adsorbed the factor XIII antibody in the patient's plasma.

Antibodies↗
PubMed1992

Pharmacokinetics of factor VIII in humans. Obtaining clinically relevant data from comparative studies.

The pharmacokinetics of Factor VIII procoagulant activity (FVIII:C) were investigated in 10 patients receiving 2 different high purity concentrates of FVIII. The in vivo recovery of FVIII:C depended on the method of blood volume estimation and on the in vitro assay used to define the potency of the concentrate; more generally, it also depends on the study design. The use of in vivo recovery to compare FVIII preparations should therefore be discouraged and the achieved area under the FVIII activity-time curve (AUC) should be used instead. The volume of distribution at steady-state (Vss) of FVIII:C was significantly greater than the estimated plasma volume of the patients. The mean terminal half-life of FVIII:C was slightly assay-dependent, being 14h by a 1-stage clotting assay and 12h by a chromogenic assay. The calculated apparent clearance (CL) of FVIII:C, as well as the Vss and the in vivo recovery, depended on the measured in vitro potency of the FVIII concentrate. These methodological aspects of pharmacokinetic studies are of direct interest to the clinician, since the routine administration of FVIII is based on the pharmacokinetic properties of the specific preparation.

Chromatography, Affinity↗
PubMed1992

Histologic studies of splenic megakaryocytes after bone marrow ablation with strontium 90.

We previously showed that purified strontium 90 produced sustained bone marrow ablation in mice, lowering platelet levels to less than 10% of normal 11 days after administration. Platelet levels later rose exclusively from splenic production and were maintained at a stable level (58% of normal) from 20 to 115 days after injection. However, there was no change in the total number or ploidy distribution of splenic megakaryocytes, as immunologically detected by flow cytometry. To further study the characteristics of splenic thrombopoiesis after bone marrow ablation by 90Sr, we measured the frequency, cross-sectional area, and endomitotic figures of histologically recognizable megakaryocytes (as well as bare megakaryocyte nuclei) in mouse spleen sections. During the hematopoietic nadir 9 days after injection of yttrium 90-free 90Sr, the size (area) of megakaryocyte cross-sections (mean +/- SD, 1079.3 +/- 661.6 microns 2; normal, 398.7 +/- 192.8 microns 2) was greater than for any other time studied, but megakaryocyte frequency (corrected for size) did not increase until day 16. Overall, splenic megakaryocytes in marrow-ablated mice 16 or more days after 90Sr injection showed substantial increases (p = 0.001 for both comparisons) in mean area (707.5 +/- 386.2 microns 2) and sectional frequency (mean +/- SEM, 4.52 +/- 0.20 per 1.83 mm2; normal, 0.78 +/- 0.06 per 1.83 mm2). Megakaryocyte bare nuclei and endomitotic figures were also more numerous after 90Sr, injection, suggesting acceleration of megakaryocyte maturation and platelet production. The induction of splenic platelet production after bone marrow ablation is associated with increased size of recognizable megakaryocytes, despite lack of change in overall splenic megakaryocyte ploidy.

Animals↗
PubMed1991

Stimulation of megakaryocytopoiesis in mice by human recombinant interleukin-6.

The in vivo effects of purified human recombinant interleukin-6 (IL-6) on murine megakaryocytopoiesis were examined. IL-6 was administered subcutaneously to Swiss Webster mice, followed by evaluation of bone marrow megakaryocyte ploidy, size and frequency, and median platelet volume 24, 48, and 72 hours after the initiation of IL-6 administration. In addition, bone marrow megakaryocyte morphology was examined using electron microscopy at 72 hours. IL-6 (10,000 U per subcutaneous injection) was administered three times during the first 24 hours, three times during the second 24 hours, and twice during the last 24-hour period. IL-6 bioactivity (10 U/ng) was determined using the IL-6-dependent murine hybridoma cell line B9. Megakaryocyte ploidy distribution, measured by two-color flow cytometry, demonstrated a shift in the modal ploidy class from 16N to 32N and a significant increase in the relative frequency of 64N megakaryocytes 48 and 72 hours (but not 24 hours) after initiation of IL-6 administration (cumulative doses of 60,000 and 80,000 U at 48 and 72 hours, respectively). In addition, ploidy levels were increased in animals that received a cumulative IL-6 dose of only 40,000 U (evaluated after 72 hours). The size of recognizable bone marrow megakaryocytes, determined by the cross-sectional areas of plastic embedded bone marrow megakaryocytes, was increased at the 48-hour (60,000 U IL-6) and 72-hour (80,000 U IL-6) time points. Megakaryocyte frequency, measured by flow cytometry, was unaffected at all time points and doses of IL-6. Median platelet volume, measured by electrical impedance, was not consistently altered by administration of IL-6. Electron microscopic examination of bone marrow megakaryocytes showed an increase in the proportion of megakaryocytes with a wide, peripheral, organelle-deficient zone from 20% +/- 9% (SD) in control animals to 50% +/- 7% (SD) (P less than .02) in animals that received IL-6. No changes were observed in the distribution of the demarcation membranes. IL-6 is a potent stimulator of murine megakaryocytopoiesis, in vivo, and appears to act early in megakaryocyte differentiation.

Animals↗
PubMed1991

Anxiolytic-hypnotic drugs: relationships between prescribing, abuse and suicide.

In 1978 the third largest Swedish city, Malmö, known to have the highest suicide frequency in the country, was found to have a higher prescription rate (defined daily doses (DDD) per 1,000 inhabitants per day) of anxiolytic-hypnotic drugs (AHD) than the country, the corresponding county, other counties, and other cities, including the largest (Stockholm) and second largest (Göteborg = Gothenburg) cities. Barbiturate prescribing in Malmö was 40% higher than in Stockholm and 90% higher than in Göteborg, and the frequency of suicide due to barbiturates was three-times higher than in Göteborg. A small proportion (2.4% of all AHD-prescribing doctors) of private practitioners wrote a large percentage (24%) of all AHD prescriptions. Prescription surveillance and an information campaign in Malmö were accompanied by a 4-year decrease in AHD prescribing (12%), in AHD abuse (40%), in barbiturate prescribing (45%), and in barbiturate suicides (70%). The total suicide rate was reduced by 25%. There was no corresponding 4-year increase in suicide due to other drugs, or by other means, but after 5 to 7 years there was an increase in suicide by non-pharmacological means. The contribution of benzodiazepines to the frequency of suicide was very small, whereas their contribution to AHD abuse was considerable. In Göteborg, where no corresponding intervention was carried out, there was also a reduction in barbiturate prescribing (34%) and in barbiturate suicides (45%), but in contrast there was a continuous increase both in overall AHD and benzodiazepine prescribing, surpassing Malmö after 5 years. Far from a reduction there was a 7-year increase in the overall frequency of suicide. Apparently, AHD abuse and suicide can be greatly reduced by restricted prescribing of AHD, and this may but need not be accompanied by an increase in suicide by other means. Targeted drug information campaigns may assist in changing prescription patterns and their medical and social impact.

Anti-Anxiety Agents↗
PubMed1991

A new assay for transglutaminase.

A new solid-phase micro assay for transglutaminase has been developed. Casein bound to microtitre plates and biotin-labelled casein were used as substrates in a transglutaminase-dependent cross-linking reaction. The resulting immobilized biotin was visualized by addition of avidin-labelled alkaline phosphatase followed by p-nitrophenyl phosphate. The colour development was monitored at 405 nm. Tissue transglutaminase was used as test enzyme. The method was also applied to normal and Factor XIII-deficient plasma.

Alkaline Phosphatase↗
PubMed1991

Transglutaminase differentiation during maturation of human blood monocytes to macrophages.

There are divergent reports in the literature on the character of transglutaminases in monocytes and macrophages. The aim of the present study was to further elucidate the characteristics and functions of various transglutaminases in monocytes and macrophages. Peripheral human blood monocytes were plated and cultured for up to a month and examined for transglutaminase. Freshly prepared monocytes contained cellular Factor XIII only. Successively during culturing, the monocytes matured into macrophages. Cellular Factor XIII correspondingly disappeared and tissue transglutaminase increased during the same time. After approximately 2 weeks in culture only tissue transglutaminase was detected and this remained for the rest of the culturing period. The tissue transglutaminase content was induced by addition of 2 mumols/l retinoic acid. Addition of retinoic acid was not critical for transglutaminase differentiation. Transglutaminase could be associated with phagocytosis of 125I-trypsin-alpha 2-macroglobulin complexes. The phagocytotic capacity of monocytes was approximately 1/4 compared to macrophages cultured for 14 days. Phagocytosis was measured as cellular complex degradation to monoiodo-tyrosine, released to the culture medium. The monocytes and macrophages were incubated at 4 degrees C and 37 degrees C, with and without addition of the transglutaminase inhibitor monodansylthiacadaverine. Addition of 100 mumols/l monodansylthia-cadaverine caused approximately 2/3 inhibition of phagocytosis. These results suggest that transglutaminase differentiates from cellular Factor XIII into tissue type transglutaminase during maturation of monocytes into macrophages and that the differentiation is associated with transglutaminase-dependent phagocytosis.

Animals↗
PubMed1988

Rifampicin quinone is an immunosuppressant, but not rifampicin itself.

Rifampicin as a potential immunosuppressive agent was tested in the rat. A freshly made-up solution of this labile antibiotic in a daily dosage of 20 mg/kg iv did not affect mean graft survival time in a heterotopic heart transplant model. However, when stored solutions of rifampicin were used mean graft survival time was significantly prolonged (from 8.2 +/- 0.4 days with the controls to 18.1 +/- 1.2 days). A similar prolongation was observed when rifampicin quinone, the major rifampicin oxidation product, was administered. We conclude that the immunosuppressive effect ascribed to rifampicin is in fact due to its oxidation product, rifampicin quinone.

Animals↗
PubMed1987

Prevention of recurrent acute cystitis by methenamine hippurate: double blind controlled crossover long term study.

In a randomised, double blind, long term, crossover study 1 g twice daily of methenamine hippurate was compared with placebo for its preventive effect on recurrent attacks of acute cystitis. Methenamine hippurate and placebo were interchanged every six months for two years. During one of the years patients took 250 ml extra fluid every morning and evening. Out of 21 enrolled patients, 14 completed the first year and 13 both years of treatment, which permitted the evaluation of 27 patient years. There were 52 episodes of acute cystitis caused by reinfection: 41 occurred during placebo treatment and only 11 during the methenamine hippurate regimen (p less than 0.01). Extra fluid intake did not reduce the incidence of acute cystitis, nor did it reduce the effect of methenamine hippurate. Methenamine hippurate is an effective prophylactic agent against recurrent acute cystitis and has the advantage of not inducing cross resistance to conventional antibiotics.

Acute Disease↗
PubMed1987

Lymphocyte transglutaminase function may be impaired in type 2 diabetes mellitus.

A method for capping of beta 2-microglobulin involving the transglutaminase inhibitor monodansylthiacadaverine was applied to lymphocytes from 17 patients with Type 2 diabetes mellitus and from a matched control group of 16 normoglycaemic healthy subjects. Monodansylthiacadaverine strongly inhibited the capping, which points to the involvement of transglutaminase in the redistribution of beta 2-microglobulin on the cell surface. The inhibition was more pronounced in lymphocytes from diabetic patients, indicating impaired transglutaminase function in Type 2 diabetes mellitus.

Cadaverine↗