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Biomedical subjects

H A Hansson

Publications and source records attributed to H A Hansson.

At least 19 recordsLinked to original sources
PubMed2000

Neck injuries in car collisions--a review covering a possible injury mechanism and the development of a new rear-impact dummy.

A review of a few Swedish research projects on soft tissue neck injuries in car collisions is presented together with some new results. Efforts to determine neck injury mechanisms was based on a hypothesis stating that injuries to the nerve root region in the cervical spine are a result of transient pressure gradients in the spinal canal during rapid neck bending. In experimental neck trauma research on animals, pressure gradients were observed and indications of nerve cell membrane dysfunction were found in the cervical spinal ganglia. The experiments covered neck extension, flexion and lateral bending. A theoretical model in which fluid flow was predicted to cause the transient pressure gradients was developed and a neck injury criterion based on Navier-Stokes Equations was applied on the flow model. The theory behind the Neck Injury Criterion indicates that the neck injury occurs early on in the rearward motion of the head relative to the torso in a rear-end collision. Thus the relative horizontal acceleration and velocity between the head and the torso should be restricted during the early head-neck motion to avoid neck injury. A Bio-fidelic Rear Impact Dummy (BioRID) was developed in several steps and validated against volunteer test results. The new dummy was partly based on the Hybrid III dummy. It had a new articulated spine with curvature and range of motion resembling that of a human being. A new crash dummy and a neck injury criterion will be very important components in a future rear-impact crash test procedure.

Accidents, Traffic↗
PubMed1998

Dorsal root ganglion nerve cells transiently express increased immunoreactivity of the calcium-binding protein S-100beta after sciatic nerve transection.

Transiently increased immunoreactivity of the calcium binding protein S-100beta was demonstrated in spinal ganglion nerve cells after sciatic nerve transection. Neuropeptide Y (NPY), normally not seen in these nerve cells, appeared concomitantly. The transiently elevated co-expression of S-100beta and NPY is proposed to reflect an increased demand of neurotrophic and neuroprotective compounds in reactive neurons, tentatively regulating calcium ions.

Animals↗
PubMed1998

[Nerve cell damages in whiplash injuries. Animal experimental studies].

Mechanical loading of the cervical spine during car accidents often lead to a number of neck injury symptoms with the common term Whiplash Associated Disorders (WAD). Several of these symptoms could possibly be explained by injuries to the cervical spinal nerve root region. It was hypothesised that the changes in the inner volume of the cervical spinal canal during neck extension-flexion motion would cause transient pressure changes in the CNS as a result of hydro-dynamic effects, and thereby mechanically load the nerve roots and cause tissue damage. To test the hypothesis, anaesthetised pigs were exposed to experimental neck trauma in the extension, flexion and lateral flexion modes. The severity of the trauma was kept below the level where cervical fractures occur. Transient pressure pulses in the cervical spinal canal were duly recorded. Signs of cell membrane dysfunction were found in the nerve cell bodies of the cervical spinal ganglia. Ganglion injuries may explain some of the symptoms associated with soft-tissue neck injuries in car accidents. When the pig's head was pulled rearward relative to its torso to resemble a rear-end collision situation, it was found that ganglion injuries occurred very early on in the neck motion, at the stage where the motion changes from retraction to extension motion. Ganglion injuries did not occur when pigs were exposed to similar static loading of the neck. This indicates that these injuries are a result of dynamic phenomena and thereby further supports the pressure hypothesis. A Neck Injury Criterion (NIC) based on a theoretical model of the pressure effects was developed. It indicated that it was the differential horizontal acceleration and velocity between the head and the upper torso at the point of maximum neck retraction that determined the risk of ganglion injuries.

Animals↗
PubMed1997

Gel matrix vehicles for growth factor application in nerve gap injuries repaired with tubes: a comparison of biomatrix, collagen, and methylcellulose.

The repair of nerve gap injuries with tubular nerve guides has been used extensively as an in vivo test model in identifying substances which may enhance nerve regeneration. The model has also been used clinical nerve repair. The objective of this study was to compare three different gel matrix-forming materials as potential vehicles for growth factors in this system. The vehicles included a laminin containing extracellular matrix preparation (Biomatrix), collagen, and a 2% methylcellulose gel. The growth factor test substance consisted of a combination of platelet-derived growth factor BB (PDGF-BB) and insulin-like growth factor I (IGF-I). An 8-mm gap in rat sciatic nerve was repaired with a silicone tube containing each of the vehicles alone or with a combination of each vehicle plus PDGF-BB and IGF-I. At 4 weeks after injury, the application of the growth factor combination significantly stimulated axonal regeneration when applied in methylcellulose or collagen, but not in Biomatrix. A similar trend was present between the vehicle control groups. By 8 weeks after injury, nerves repaired with methylcellulose as a vehicle had significantly greater conduction velocity than either collagen or Biomatrix. It was concluded that a 2% methylcellulose gel was the best of the three matrices tested, both in its effects on nerve regeneration and flexibility of formulation.

Animals↗
PubMed1996

Comparison among different approaches for sampling cerebrospinal fluid in rats.

Two approaches for time-resolved sampling of cerebrospinal fluid (CSF) in rats were compared regarding performance, reproducibility, and extent of the inevitable trauma caused by the implantation of a sampling tube. Several parameters were checked to evaluate the injury: blood cell contamination of CSF; concentrations in CSF of the cytosolic proteins neuron-specific enolase (NSE) and S-100 (chiefly present in astrocytes); blood-brain barrier leakage of a dye-protein complex; viability of nervous tissue cells as assessed by dye exclusion; light and electron microscopy. In one sampling method, a tube was forced epidurally into the cisterna magna via a hole in the calvarium, consistently damaging the meninges and the nervous tissue. When using the alternative sampling method, the tube was instead affixed to the posterior atlanto-occipital membrane and connected with the cisterna magna via a hole in the membrane. Such a procedure caused negligible damage. Both techniques induced an inflammatory response. We advocate the use of the second approach, i.e., to sample CSF via a hole in the atlanto-occipital membrane, as the method of choice due to its high reproducibility. It is fairly rapid, and associated with a negligible injury.

Animals↗
PubMed1996

Increased expression of xanthine oxidase and insulin-like growth factor I (IGF-I) immunoreactivity in skeletal muscle after strenuous exercise in humans.

The present study investigated the effect of 7 days of strenuous exercise on the quantity of xanthine oxidase and IGF-I in muscle. Fifteen male military trainees performed 1 week of terrain marching and warfare exercises. Muscle biopsies and blood samples were obtained prior to and after the week. After the week, the number of xanthine oxidase immunoreactive cells, identified as capillary endothelial cells and leucocytes, and the number of IGF-I immunoreactive cells, mainly vascular cells but also cells tentatively identified as satellite cells, were higher in the muscle (P < 0.05). Plasma creatine kinase activity was 650% higher after the week (P < 0.001) and the muscle content of hydroxyproline was elevated by 160% 2 months post-exercise (P < 0.05), both findings implying injury to the muscle. The present data provide a first observation of an elevated level of xanthine oxidase and IGF-I in human skeletal muscle after exercise. It is proposed that both substances increased as a result of cellular damage: xanthine oxidase because of the influence of immunomodulators, and IGF-I in association with regenerative processes. The increased expression of IGF-I in the muscle could, however, also reflect cellular growth in response to an elevated load on the muscle and the vascular bed.

Adult↗
PubMed1996

Membrane leakage in spinal ganglion nerve cells induced by experimental whiplash extension motion: a study in pigs.

Nerve cells in the cervical and upper thoracic spinal ganglia were examined for possible plasma membrane leakage, as revealed by their ability to exclude a dye-protein complex, after experimentally induced whiplash in a pig model system. The rationale for this approach is found in the fact that the interstitium of spinal ganglia differs from most other parts of the nervous system in that it lacks a barrier, allowing blood constituents to gain access. The dye Evans blue, which rapidly conjugates with blood proteins, is found in the interstitium of normal spinal ganglia after intravenous injection, but it is excluded from the nerve cells and their enveloping satellite cells. In contrast, after a simulated whiplash extension trauma many of the nerve cells were stained, reflecting the inability of their plasma membranes to exclude the dye-protein complex. Morphometric measurements revealed that the highest frequency of cellular dye uptake was observed in the C4-C7 spinal ganglia (mean 16 - 18%; range 5-27%). The blood-nerve barrier of the adjacent nerve fascicles remained intact, with rare exception. Several factors are considered to contribute to the induction of these cell abnormalities in the spinal ganglia after an experimentally induced, simulated whiplash trauma in this pig model system.

Animals↗
PubMed1995

A new approach for multiple sampling of cisternal cerebrospinal fluid in rodents with minimal trauma and inflammation.

A new approach was developed to minimize inevitable damage to nervous and meningeal tissue due to implantation of a sampling tube allowing multiple withdrawal of cerebrospinal fluid (CSF) from the cisterna magna in adult rats. A tube was secured on the atlanto-occipital membrane. Thereafter, a hole was cut through the membrane, allowing flow of CSF from the cisterna magna to the tube. CSF could be sampled repeatedly for at least 1 week. There was no blood-brain barrier damage. The pressure in the cisterna magna remained normal as did the estimated rate of CSF formation. Very few blood cells contaminated the CSF. There was very little evidence of inflammation. The nervous tissue was undamaged as shown by exclusion of a dye-protein complex. The CSF concentrations of the cytosolic neuronal protein neuron-specific enolase (NSE), and of the astrocyte protein S-100 were very low. The pattern of amino acids remained within normal limits. Scanning electron microscopy revealed that clot and reactive changes were restricted to the vicinity of the connecting hole. We conclude that our approach to positioning a tube on the atlanto-occipital membrane and then connecting it to the cisterna magna reproducibly and reliably enables 'atraumatic' multiple sampling of CSF.

Amino Acids↗
PubMed1995

Helicobacter pylori interacts with heparin and heparin-dependent growth factors.

The pathogenic bacterium Helicobacter pylori, which causes active, chronic type B gastritis and peptic ulcer disease, and increases the risk for development of gastric cancer, could tentatively interfere with growth factors and growth factor receptors of importance for the gastroduodenal mucosa, e.g. heparin-binding FGFs (fibroblast growth factors). H. pylori binds FGF with an extremely strong affinity (3.8 x 10(-12)M), and also heparan sulfate and heparin with higher affinity (Kd 9 x 10(-9)M) than FGFs bind to heparin (10(-8) - 10(-9)M). FGF receptors are also dependent on heparin for their activation. Heparan sulfate binding proteins (HSBP) are exposed on and shed from the surface of H. pylori, which often are localised close to the epithelial stem cells in the gastroduodenal glands. H. pylori could thus efficiently interfere with growth factors and growth factor receptors, tentatively resulting in disturbance of the delicate balance that control the renewal, maintenance and repair of the gastroduodenal mucosa. This mode of action has previously not been considered, but may constitute part of its pathogenic mechanisms. Such a dynamic mode of action of H. pylori may explain the reason for that infected victims may either suffer from gastrointestinal symptoms or lack clinical evidence of disease or discomfort.

Fibroblast Growth Factor 1↗
PubMed1993

Peptide growth factors and myofibroblasts in capsules around human breast implants.

Peptide growth factors were mapped immunohistochemically for assessment of their presumed relation to the cells in capsules enveloping gel-filled, smooth-surfaced silicone mammary implants (12 capsules from 11 women). The implant capsules were dominated by fibroblast-like cells, but there were as well macrophages, inflammatory cells, and vascular cells. These cells expressed immunoreactivity for TGF-beta, IGF-II, IGF-I, and, to a lesser extent, PDGFB, NGF, and TNF-alpha. The numerous spindle-shaped cells in the contracted capsules displayed several distinct cytoplasmic actin bundles and fulfilled ultrastructural criteria for myofibroblasts. In contrast, myofibroblasts were recognized in low frequencies in the noncontracted capsules. Mature skin scar tissue did not show any peptide growth factor immunoreactivity, and myofibroblasts were absent. It is postulated that the low-grade chronic inflammatory foreign-body reaction, aggravated by mechanical stress and possible leakage of irritants, stimulates capsule cells to form peptide growth factors, reflecting that extended healing processes prevail in both noncontracted and contracted capsules. We propose that the local enrichment of peptide growth factors, beneficial for acute wound healing, in the chronically irritated tissue around implants provides trophic support for the contractile cells in the implant capsules.

Biopsy↗
PubMed1993

Glutathione transferases of classes alpha, mu and pi show selective expression in different regions of rat kidney.

1. Glutathione transferases (GST) are mainly cytosolic and occur in multiple forms, which can be arranged in three distinct, structural classes. The different enzyme forms show distinct substrate specificities with electrophilic and genotoxic substances. The expression of the alpha subunits 1, 2 and 8, the mu subunits 3, 4 and 6, and the pi subunit 7 of GST in different parts of the rat kidney was determined immunohistochemically. 2. GST immunoreactivity was present predominantly in the nephron, collecting duct and urothelium. 3. A conspicuous finding was that subunits 1, 2 and 8 were localized to the proximal tubules, while the mu subunit 3 was demonstrable in epithelial tubular cells from the distal tubules to the urothelium. The immunoreactivity of subunits 4 and 6 could be visualized in epithelial cells from the ascending thin limb to the collecting ducts. Subunit 7 was found in the thin limb of the loop of Henle, and in scattered cells in the distal tubules. 4. The urothelial cells covering the papilla and the renal calyces showed immunoreactivity to GST subunits 2-4 and 6-8. 5. Thus, in the nephron the class alpha GSTs were selectively expressed in the proximal tubules and the class mu and class pi GST in the thin loop of Henle and distal tubules. The cells in the collecting ducts and the urothelium, which have a different ontogeny than the nephron, do not show any corresponding differential distribution of the GST classes. 6. Cells in a given location were in some cases found to be non-reactive with a given antiserum in an otherwise immunoreactive cell population, demonstrating a spatial variation in GST expression. The immunoreactivity to the different forms of GST was predominantly cytoplasmic but a nuclear localization could also be demonstrated. 7. The panel of antibodies to GST may tentatively be used as markers in localizing lesions in restricted parts of the nephrons and to elucidate dynamic alterations in the tubular system in response to physiological and toxic agents.

Animals↗
PubMed1991

Immunohistochemical distribution of isoenzymes of glutathione transferase in adult rat adrenal gland before and after hypophysectomy.

The distribution of glutathione transferase subunits 1, 2, 3, 4, 7 and 8 in the different cells of the female and male rat adrenal and the effects of hypophysectomy on these isoenzymes were studied using immunohistochemical methods. All these glutathione transferase subunits, with the exception of subunit 1, were present in the adrenal. Each subunit showed, however, its own characteristic distribution pattern. After hypophysectomy, increased staining for these isoenzymes was generally observed, and this effect was also cell-specific. Staining for subunit 2 increased in intensity in the zona fasciculata and reticularis after hypophysectomy, whereas a decrease was observed in the zona glomerulosa. Staining for subunit 8 was increased in the borderline between the capsule and zona glomerulosa, as well as in medullary chromaffin cells after hypophysectomy. The Mu subunits 3 and 4 increased markedly in fascicular and reticular cells after hypophysectomy and staining for subunit 3 was also increased in the medullary cells. A slight, but more general, increase was observed for subunit 7. We conclude from these experiments that the increases in glutathione transferase subunits observed in the rat adrenal after hypophysectomy are due to increased protein synthesis and/or increased protein stability and not to a selective destruction of cells lacking, or with low levels of, the isoenzymes.

Adrenal Glands↗
PubMed1991

Regenerating human nasal mucosa cells express peptide growth factors.

The goal of this study was to investigate if the distribution of peptide growth factors in the human nasal mucosa could be correlated to its maintenance and to repair processes. Biopsy specimens from clinically healthy humans, aged 6 months to 70 years, were investigated immunohistochemically. In the intact human nasal mucosa, only scattered basal epithelial cells and rare, randomly distributed cells in the lamina propria expressed peptide growth factor immunoreactivity. In contrast, in areas with deficient epithelial lining and infiltration of inflammatory cells, intense insulinlike growth factor I immunoreactivity was demonstrable in reactive epithelial cells, while adjacent, more differentiated cells were nonreactive. Vascular wall cells, fibroblasts, macrophages, and exocrine gland cells in the reactive nasal mucosa showed variable insulinlike growth factor I immunoreactivity and, at lower frequencies and intensities, immunoreactivity to insulinlike growth factor II, basic fibroblast growth factor, platelet-derived growth factor, and transforming growth factor beta, as did cells in the normally nonreactive exocrine glands. Macrophages and vascular smooth-muscle cells could in addition express platelet-derived growth factor immunoreactivity. Increased cell proliferation was recognized in reactive areas of the nasal mucosa specimens, ie, in those concomitantly showing distinct peptide growth factor immunoreactivity. We concluded that a complex pattern of peptide growth factor immunoreactivity is transiently expressed by reactive and regenerating nasal mucosal cells, contrasting with the nonreactive normal, differentiated cells. The close correlation between the appearance of peptide growth factors and the local repair and maintenance processes supports our working hypothesis that peptide growth factors are of functional importance for the nasal mucosa.

Adolescent↗
PubMed1991

Immunoreactivities for epidermal growth factor (EGF) and for EGF receptors in rats with gastric ulcers.

The present study was aimed at assessing whether epidermal growth factor (EGF) and its receptors are present in the gastric mucosa during the healing of gastric ulcers. Immunohistochemical, immunochemical and functional studies were performed in rats after induction of ulcers in the oxyntic mucosa. Controls, which included non-operated and sham-operated animals, displayed only rare cells in the bottom of the oxyntic glands showing EGF-like immunoreactivity. Within one day after ulcer induction, a markedly increased number of chief cells in undamaged mucosa showed intense staining. Concomitantly, there was an increased immunoreactivity for EGF receptors in the mucous neck cells. Maximal immunostaining for both compounds was observed at 3 days after ulcer induction; augmented staining was still demonstrable after 3 weeks. RIA revealed significantly increased EGF concentration in the oxyntic mucosa three days after ulcer induction, and at this stage stimulated gastric acid secretion, measured in a parallel group of chronic fistula rats, indicated significant inhibition. The transient increases in EGF-like and EGF receptor immunoreactivities may stimulate gland cell proliferation. The local release of EGF-like substances may also serve to reduce gastric acidity and thereby promote ulcer healing.

Animals↗
PubMed1991

Nasal mucosal changes in children treated with gammaglobulin. Aspects on middle ear pathology and nasopharyngeal bacteriology.

The present study was undertaken to evaluate possible beneficial effects of gammaglobulin treatment every 3 weeks during 6 months of 6-month to 2-year-old children. Every second of 44 children with recurrent acute otitis media (RAOM) received gammaglobulin, the other 22 served as controls. Nasal mucosal biopsy specimens were taken at 6-month intervals and analysed by light microscopy (LM) and scanning electron microscopy (SEM). Additional biopsies were obtained from another 15 children with RAOM and from 27 "healthy" children. No morphological differences in nasal mucosa could be demonstrated between the gammaglobulin treated and non-treated children. The structural changes observed in the first biopsy specimens usually persisted for at least 6 months, i.e. the study period, and were most prominent in the epithelium. Children with two or more episodes of acute otitis media (AOM) during the study period had more microabscesses compared to the children without any episode of AOM. Microabscesses were also more common in cases with secretory otitis media compared to cases with normal middle ear status. No morphological differences could be revealed related to the age of the children. Microabscesses, cell destruction and discontinuity of the epithelial lining were more common in children who harboured Branhamella catarrhalis in their nasopharynx. We conclude that intramuscular administration to children of gammaglobulin every 3 weeks during half a year neither improved their resistance to RAOM nor reduced the frequency or extent of structural changes in their nasal mucosa.

Abscess↗
PubMed1990

Qualitative interfacial study between bone and tantalum, niobium or commercially pure titanium.

Tantalum (Ta), niobium (Nb) and commercially pure titanium (c.p. Ti) were sputtered on to the surfaces of polycarbonate plastic implants. After 3 month of insertion, in the tibial metaphysis of rabbits, the implants were removed with a surrounding bone collar and processed for light (LM) and electron microscopy (EM). By EM a zone of ground substance tens of nanometers wide without collagen filaments was noticed surrounding the Ta implants. Multinucleated macrophages could occasionally be recognized in the interface zone. Foreign body reactions were more striking at the Nb interface while no multinucleated macrophages were observed in the c.p. Ti interface. The ground substance layer had a thickness in the range of 40-60 nm for the Nb implants, whereas in c.p. Ti sections the collagen filaments were noticed 20-40 nm from the metal surface. There are more subtle differences between tantalum and c.p. titanium than between c.p. titanium and niobium which seems to be less well tolerated when implanted in bone.

Animals↗
PubMed1990

Vibration exposure and peripheral nerve fiber damage.

The hind leg of adult rats was exposed to vibrations (82 Hz; amplitude peak-to-peak 0.21 mm) for 4 hours during 5 consecutive days. Light and electron microscopic examination of the plantar and sciatic nerves were done immediately after the exposure period or after a 2- or 4-week recovery period. Light microscopic examination did not reveal any distinct signs of injury. However, ultrastructurally unmyelinated fibers in the plantar nerves showed distinct changes, with deranged axoplasmic structure and/or accumulation of smooth endoplasmatic reticulum. These changes were to a large extent reversible in 2 weeks and appeared normalized after a 4-week recovery period. No ultrastructural changes could be observed in the sciatic nerve. However, when the sciatic nerve was crushed after 5 days of vibration exposure, axonal outgrowth was increased 23% as compared with controls. These findings confirm that vibration induces nerve fiber damage, in this experimental model expressed as a "conditioning effect" contributing to increased regeneration potential of the corresponding neurones.

Animals↗