Biomedical subjects

L Strömberg

Publications and source records attributed to L Strömberg.

At least 37 records · Page 2Linked to original sources

PubMed1988

Induced cervical ripening with Mifepristone in first trimester abortion. A double-blind randomized biomechanical study.

Mifepristone (RU 486; Roussel-Uclaf, Paris, France) is an antiprogesterone used for termination of very early pregnancy. The ripening effect of Mifepristone on the human pregnant cervix was studied in 42 healthy women from 7 to 11 weeks gestation. The women were randomly allocated to oral treatment of either 100 mg Mifepristone or placebo for 24 and 12 hours before vacuum aspiration. An objective method has been designed to measure the force necessary to step-wise dilate the cervix from 4 to 11 mm. Significant (p less than 0.05) changes in the stiffness of the cervix were demonstrated in patients treated with Mifepristone, reflecting ripeness. The treatment was simple and had no side effects.

Abortion, Induced↗

PubMed1988

No effect of growth hormone on recovery of load-protected bone. Cortical bone mass and strength studied in rabbits.

The effect of human growth hormone on the recovery of a previously atrophied diaphyseal bone, stress-shielded by plating, was studied in 56 adult rabbits using the contralateral tibia as a control. At removal of the plates, an initial 40 per cent reduction of torsional strength was seen. The strength was normalized in 3 weeks. A concomitant reduction of bone mineral density was normalized in 1.5 weeks. No difference in the rate of strength regeneration was found between growth hormone-treated rabbits and controls. In the treated rabbits an increase in cortical bone area due to subperiosteal new bone formation was seen in previously plated bones, as well as in sham-operated bones.

Animals↗

PubMed1987

Stress stimuli-induced histopathological changes in the prostate: an experimental study in the rat.

To elucidate a suggested relationship between stress stimuli and prostatis, a histological study on the genital organs of seven rats was performed. The specimens were histopathologically examined after a 10-day period, during which the rats had been submitted to standardized stress stimuli, and compared with corresponding organs from a control group of seven male rats. Inflammatory histopathological changes and large numbers of inflammatory cells were seen in the prostatic glands of all rats submitted to the long-term stress stimuli. The findings agreed with those from the prostatic glands of human males with prostatis. No corresponding changes were observed in the control group. There was no evidence indicating a bacterial origin. The results indicate a connection between stress stimuli and prostatitis.

Animals↗

PubMed1987

Blood perfusion of the male genital organs--an experimental study in the rat.

Male genital blood flow and its regulation have not been fully clarified. In the present study we employed a radioactive microsphere technique to estimate the blood flow simultaneously in the major urogenital organs of male rats. The recorded genital flow rates varied among the rats. The relative blood perfusion rates of the testicles, seminal vesicles and kidneys did not differ from one animal to another. However, the blood flow in the prostate gland was not correlated to the perfusion of any of the other investigated urogenital organs.

Animals↗

PubMed1987

Genital blood flow in male rats subjected to stress stimuli.

A common opinion among physicians is that some symptoms from the prostate gland are stress-dependent. However, no experimental support for this view has been presented. In the present study blood perfusion of the major genital organs of male rats were measured after they had been subjected to experimental "short- and long-term" stress stimuli. The blood-flow measurements were made by means of a radioactive microsphere technique. The used experimental "short-term" stress reduced the prostatic blood flow by approximately 50 percent. A decreased blood flow and a concomitant atrophy, indicating that the reduction in blood flow has been in force over a prolonged period of time, were noticed in all examined genital organs of the rats subjected to prolonged stress stimuli. The decreases in blood flow and weight were most pronounced in the prostate gland.

Animals↗

PubMed1987

Plasma testosterone concentrations in male rats during short and long-term stress stimulation.

Plasma testosterone concentrations were analysed in 14 male rats submitted to short-term and prolonged stress stimulation, and the results were compared with those obtained from a control group of seven rats not submitted to the corresponding experimental stress stimuli. Increased levels of circulating testosterone were recorded during the short term stress stimulus. As compared with the control group, plasma testosterone concentrations were reduced after prolonged stress stimulation for 10 days. The increased stress stimulation, that the animals subjected to short- and long-term standardized stress stimuli were subjected to, compared to the corresponding stress of the animals in the control group, was reflected in an increased concentration of catecholamines in arterial blood.

Animals↗

PubMed1986

Physical properties of autoclaved bone. Torsion test of rabbit diaphyseal bone.

Structural properties of autoclaved diaphyseal bone in the rabbit were investigated by torsional test. Heat propagation into the bone was studied by means of thermocouples. The torsional test included 54 pairs of diaphyseal bones. Autoclaving was performed to the same degree of sterilization, although with variations of time and temperature. Standard autoclaving at 121 degrees C for 20 min was found to cause a moderate decrease (23 per cent) in torsional strength. The decrease was more pronounced (35 per cent) for bones autoclaved at 110 degrees C for 255 min and less (9 per cent) for those autoclaved at 131 degrees C for 2 min. Heat propagation into bone during autoclaving proved to be rapid at both 121 degrees C and 131 degrees C, indicating that complete, uniform sterilization of diaphyseal bone may be performed to an accurate, predetermined degree. Diaphyseal bone subjected to standard autoclaving remains mechanically adequate for skeletal substitution. Reimplantation of autoclaved tumorous bone might provide a simple combined means for tumor devitalization and subsequent reconstruction.

Animals↗

PubMed1986

The influence of nylon cerclage on diaphyseal bone strength: an experimental evaluation of Partridge bands on rabbits.

Partridge-designed nylon bands which are used for the cerclage of fractured osteoporotic bones. These bands were given elevations on their inner surfaces to raise the band from the bone surface and thus minimize the negative effects on the periosteal blood circulation. It has previously been shown that the Partridge bands, when applied to a diaphyseal bone, cause a mechanical irritation to the periosteum resulting in an increased callus formation by comparison with the case when corresponding bands with no elevations are applied. It has been suggested that the increased amount of callus would result in increased strength. We have studied the effect of bands designed in accordance with Partridge, compared with corresponding bands having no elevations, in terms of torsion strength (maximum torque capacity), on intact rabbit femora. The results show an increased torsion strength in the femora to which Partridge bands had been applied for eight weeks, while the femora to which corresponding plain nylon bands had been applied had decreased in strength. The experimental study performed supports Partridge's recommendation to use the bands as cerclage in the internal fixation of fractured osteoporotic bones, preferably in combination with further internal fixation materials.

Animals↗

PubMed1986

Intramedullary reaming and nailing: its early effects on cortical bone vascularization.

The early effect of reaming the medullary cavity prior to intramedullary nailing using Küntscher's method, on human cortical bone vascularization in the femur is discussed. In sections of the femur where the medullary tissue had been totally reamed, the inner two-thirds of the cortical bone tube was completely avascularized one week after the reaming. In the outer third of the cortex the vascularization was only moderately decreased. In the parts of the femur where the medullary tissue was not totally destroyed there was a marginal effect on the amount of intact cortical vessels. The observation is thus in accordance with corresponding results from experimental studies on animals. Microcracks, and cracks in the cortical wall, caused by the reaming and procedure are also described in the article.

Adult↗

PubMed1986

Mechanical compliance of the small intestine related to long-standing obstruction. An experimental study in rats.

Mechanical compliance was studied in rat small intestine subjected to 48 hours of simple obstruction. The values were compared with those obtained in a corresponding section of normal gut. A closed system was used, constructed for continuous measurement of volume-pressure relationships within a hollow organ. The pressure-raising velocity was regulated by programming a steering unit connected to the system. The findings accorded with the hypothesis of an increase in compliance of the obstructed small intestine. The experiments further demonstrated that repeated artificial increases in intraluminal pressure cause change in intestinal compliance.

Animals↗

PubMed1985

Growth changes of collagen cross-linking, calcium, and water content in bone.

It has been claimed that the increase in the strength of growing bone is due to increased mineral content. The strength of collagen is based on intermolecular covalent cross-links, and it has also been proposed that cross-link changes increase bone strength. Measurements of the content of calcium, collagen, and water, as well as cross-link analyses, were performed on the tibial cortex of growing dogs. Within the age range studied (8-44 weeks), no changes in calcium content expressed as a percentage of dry bone weight were seen. Collagen content expressed as weight of hydroxyproline per dry bone weight showed a minor reduction during growth. However, water content decreased considerably up to an age of about 25 weeks, which implies a concomitant increase in the amount of bone material. Of the two cross-link main groups, reducible and nonreducible, it is only possible chemically to analyze the reducible. During the final part of the period of growth and mechanical maturation of the bones, the number of reducible cross-links decreases. This indicates a concomitant increase in the more stable nonreducible forms. The possible mechanical relevance of the chemical changes found during growth is discussed.

Animals↗

PubMed1985

Torsional tests of long bones with computerized equipment.

An experimental method using a computerized torsion machine to study the mechanics of entire diaphyseal bones is described. Besides controlling continuous torsion to ultimate fracture of the bone, the computer is able to use non-linearity of the torque-twist curve as a criterion for reversal of the direction of torsion and to control repeated loadings and unloadings with a graduated increase of deformation until final fracture. It permits determination of a small residual deformation, and several other parameters characterizing the load-deformation curve. The linearity of the equipment is shown to be good and precision is high, with a method error of 2.3% when determining stiffness. Repeated loadings and unloadings of entire dog femora revealed a minor residual deformation before ultimate fracture.

Biomechanical Phenomena↗

PubMed1985

Plasma enteroglucagon in the control of childhood celiac disease.

To study whether or not plasma enteroglucagon reflects changes of the small intestinal mucosa during different phases of celiac disease, we studied fasting and postprandial concentrations of plasma enteroglucagon, as well as small intestinal mucosa morphology, in children with celiac disease and in a reference group of children without gastrointestinal disorders. The children with celiac disease were studied before dietary treatment, during gluten-free diet, and during gluten challenge. In untreated celiac children we found high mean basal and postprandial plasma enteroglucagon concentrations compared with the reference group (p less than 0.001). After a gluten-free diet period of 0.2-4.5 years (mean, 1.0 year), when the small intestinal histology was normal or only mildly abnormal, there was a decrease of both mean basal plasma enteroglucagon concentration (from 81 to 17 pmol/L; p less than 0.001) and mean postprandial plasma enteroglucagon concentration (from 129 to 39 pmol/L; p less than 0.001). During a subsequent gluten challenge, which resulted in a mucosal relapse, there was a rise in mean postprandial plasma enteroglucagon concentration (from 39 to 74 pmol/L; p less than 0.005), although there was a substantial overlap in values from treated and challenged patients. These findings suggest that plasma enteroglucagon levels, particularly after a mixed meal, are correlated with the small intestinal mucosal morphology in childhood celiac disease. Determination of plasma enteroglucagon may facilitate the control of the dietary adherence during gluten-free diet and may in some children indicate mucosal relapse during gluten challenge. Thus, the number of control biopsies may be reduced.

Adolescent↗

PubMed1985

Bodyloading on atrophied bone and bone mineral content. An experimental study in the rabbit.

The quality of a cortical bone, as reflected in the bone mineral content, has been studied in rabbit tibiae during an experimental atrophy process, and following recovery and adaptation to increased loading. Atrophy of the bone was induced by a rigid internal fixation plate applied to the tibia for 12 weeks. During the process of recovery after the plate had been removed, the bone mineral content was studied by means of an ashing procedure. The bone mineral content per unit volume cortical bone remained unchanged both at maximum atrophy and during the subsequent process of recovery.

Analysis of Variance↗

PubMed1985

The effect of athletic activity on the bone mass in human diaphyseal bone.

Both humeri of seven professional tennis players and seven controls were examined with x-ray spectrophotometry, and computed tomography. Both the bone mineral content and the cortical cross-sectional area were found to be larger in the dominant arm of the tennis players than in their non-dominant arm, and in comparison to both arms of the controls. The increase in cortical cross-sectional area was a result of an increased outer diameter of the diaphysis.

Adolescent↗

PubMed1984

Serum gliadin antibodies for detection and control of childhood coeliac disease.

Serum gliadin antibodies of the IgA and IgG isotypes were determined by means of the diffusion-in-gel enzyme-linked immunosorbent assay (DIG-ELISA) in children during different phases of coeliac disease. Fourteen children were studied before onset of dietary treatment, 16 during a period of gluten-free diet and 16 during gluten challenge. The control groups consisted of 44 children with other gastrointestinal diseases and 14 children without gastrointestinal disorders. All of the children studied had been subjected to small-intestinal biopsy. On the basis of the results obtained in this study the diagnostic sensitivity with regard to untreated coeliac disease was found to be 100% and the diagnostic specificity 97%. In 10 coeliac children followed during the phases of diagnostic evaluation antibody levels decreased in all during dietary treatment and increased in 8 during a subsequent gluten challenge. It is suggested that determination of IgA and IgG gliadin antibodies by means of DIG-ELISA may be used as a diagnostic test for coeliac disease in children and that this test may be useful in monitoring the dietary treatment in children with known coeliac disease. Moreover, the DIG-ELISA is an inexpensive and technically simple method.

Adolescent↗

PubMed1984

Uniformity in mechanics of long bones at torque. A dog experiment.

Entire and fresh pairs of tibiae and femora from dogs have been tested with a computerized torsion machine. No differences were observed within the pair for several structural parameters, ensuring a right-left congruence of the load deformation curves of the tested bones.

Animals↗

PubMed1984

Solid mechanics and strength of bone in young dogs.

Fresh tibiae and femora from 22 harriers ranging in age from 8 to 44 weeks have been studied with a computerized torsion-machine. The growth of the dogs studied ceased at an age approaching 30 weeks. The strength and stiffness of the entire bones also ceased to increase at that age, and the increase in stress at fracture and shear modulus of the bone material strongly declined in impetus. This means that no important maturation, as measured in strength of the bone material, takes place after cessation of growth. The fracture twist angle per unit bone length was greatest for the younger bones and decreased to an age of around 25 weeks; the relation, however, between the linear and the non-linear part of the torque-twist curves did not change. Furthermore, the study indicates that juvenile bones, like adult bones, are essentially elastic-brittle, and there was no sign of increased plasticity in the young bones.

Age Factors↗