SURFACE STRUCTURE OF ISOLATED NEURONS : Detachment of Nerve Terminals during Axon Regeneration

Freehand, isolated neuronal perikarya from the hypoglossal nucleus of the rabbit have been examined with light-and electron-microscopy (transmission and scanning). The surface of the cell bodies was largely covered with spherical particles which were 0.5–2 µ in diameter. Transmission electron microscopy proved that the spherical particles were synaptic nerve terminals. Crush of the hypoglossal nerve which leads to chromatolysis and swelling of the neuronal cell bodies results in a conspicuous reduction in the number of terminals attached to the surface of hypoglossal neurons. This effect was observed both for isolated neurons and in tissue sections. The effect is considered in relation to earlier reported variations in the adherence of neuropil to isolated neuronal perikarya. The functional importance of nerve ending detachment in connection with nerve injury is discussed.

A new model for diffuse brain injury by rotational acceleration: II. Effects on extracellular glutamate, intracranial pressure, and neuronal apoptosis

The aim of this study is to monitor excitatory amino acids (EAAs) in the extracellular fluids of the brain and to characterize regional neuronal damage in a new experimental model for brain injury, in which rabbits were exposed to 180-260 krad/s2 rotational head acceleration. This loading causes extensive subarachnoid hemorrhage, focal tissue bleeding, reactive astrocytosis, and axonal damage. Animals were monitored for intracranial pressure (ICP) and for amino acids in the extracellular fluids. Immunohistochemistry was used to study expression of the gene c-Jun and apoptosis with the terminal deoxynucleotidyl transferase nick-end labeling (TUNEL) technique. Extracellular glutamate, glycine, and taurine increased significantly in the hippocampus within a few hours and remained high after 24 h. Neuronal nuclei in the granule layers of the hippocampus and cerebellum were positive for c-Jun after 24 h. Little immunoreactivity was detected in the cerebral cortex. c-Jun-positive neuronal perikarya and processes were found in granule and pyramidal CA4 layers of the hippocampus and among the Purkinje cells of the cerebellum. Also some microglial cells stained positively for c-Jun. TUNEL reactivity was most intense at 10 days after trauma and was extensive in neurons of the cerebral cortex, hippocampus, and cerebellum. The initial response of the brain after rotational head injury involves brain edema after 24 h and an excitotoxic neuronal microenvironment in the first hour, which leads to extensive delayed neuronal cell death by apoptosis necrosis in the cerebral cortex, hippocampus and cerebellum.

A new model for diffuse brain injury by rotational acceleration: I model, gross appearance, and astrocytosis

Rapid head rotation is a major cause of brain damage in automobile crashes and falls. This report details a new model for rotational acceleration about the center of mass of the rabbit head. This allows the study of brain injury without translational acceleration of the head. Impact from a pneumatic cylinder was transferred to the skull surface to cause a half-sine peak acceleration of 2.1 x 10(5) rad/s2 and 0.96-ms pulse duration. Extensive subarachnoid hemorrhages and small focal bleedings were observed in the brain tissue. A pronounced reactive astrogliosis was found 8-14 days after trauma, both as networks around the focal hemorrhages and more diffusely in several brain regions. Astrocytosis was prominent in the gray matter of the cerebral cortex, layers II-V, and in the granule cell layer and around the axons of the pyramidal neurons in the hippocampus. The nuclei of cranial nerves, such as the hypoglossal and facial nerves, also showed intense astrocytosis. The new model allows study of brain injuries from head rotation in the absence of translational influences.

Blast exposure causes redistribution of phosphorylated neurofilament subunits in neurons of the adult rat brain

There is little information on threshold levels and critical time factors for blast exposures, although brain damage after a blast has been established both clinically and experimentally. Moreover, the cellular pathophysiology of the brain response is poorly characterized. This study employs a rat model for blast exposure to investigate effects on the neuronal cytoskeleton. Exposure in the range of 154 kPa/198 dB or 240 kPa/202 dB has previously been shown neither to cause visual damage to the brain, nor to affect the neuronal populations, as revealed with routine histology. Here, the brains were investigated immunohistochemically from 2 h to 21 days after blast exposure. A monoclonal antibody was used which detects only the phosphorylated epitope of the heavy subunit of the neurofilament proteins (p-NFH). This epitope is normally restricted to axons, that is, not demonstrable in the perikarya. Eighteen hours after exposure in the 240-kPa/202-dB range, p-NFH immunoreactivity accumulated in neuronal perikarya in layers II-IV of the temporal cortex and of the cingulate and the piriform cortices, the dentate gyrus and the CA1 region of the hippocampus. At the same time, the p-NFH immunoreactivity disappeared from the axons and dendrites of cerebral cortex neurons. The most pronounced immunostaining of neuronal perikarya was found in the hemisphere, which faced the blast source. The perikaryal accumulation of p-NFH was present also at 7 days but the neuronal perikarya had become negative at 21 days, at which time the axons again displayed p-NFH immunoreactivity. Exposure in the range of 154 kPa/198 dB caused similar, although less marked accumulation of p-NFH immunoreactivity in the neuronal perikarya. The findings are interpreted to show a dephosphorylation of NFHs in axons and dendrites and a piling up of p-NFHs in the perikarya due to disturbed axonal transport.

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.

[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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Pressure waves caused by high-energy missiles impair respiration of cultured dorsal root ganglion cells

High-energy missile extremity impact causes short-lasting pressure waves which traverse the body with a velocity close to that of sound in water. In order to elucidate mechanisms for distant damage in a living body to the peripheral and central nervous system, a model system was designed aimed to create pressure waves with amplitudes, frequency spectrum, and duration fairly comparable to those recorded in situ. Our model system enabled exposure of tissue cultures of dorsal root ganglion (DRG) and endothelial cells under strictly controlled conditions to a burst of oscillating pressure waves and to determine possible influence on oxygen consumption. Oscillating pressure waves caused by high-energy missile impact (velocity 1,200 m/s) reduced the oxygen consumption by more than 80%. However, in spite of this drastic, acute effect the ganglion cells and the feeder layer cells did not reveal any immediate plasma membrane dysfunctions as revealed by cytoplasmic uptake of Evans blue protein marker complexes. It is concluded that pressure waves fairly similar to those demonstrable in vivo in the vicinity of the peripheral and central nervous system after high-energy missile extremity impact in pigs reduce the respiration of DRG cells and endothelial cells in culture. The mitochondrial impairment is not associated with concomitant plasma membrane dysfunction for macromolecules. Nerve cells seem to be more vulnerable than the other type of cultured cells examined.

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.

Pressure wave injuries to the nervous system caused by high-energy missile extremity impact: Part I. Local and distant effects on the peripheral nervous system--a light and electron microscopic study on pigs

Pigs were used for studies of effects on the peripheral nervous tissue of pressure waves induced by impact and passage through the left thigh of high-energy missiles. The short-lasting pressure waves were demonstrated to move close to the speed of sound and to have a spectrum of high frequencies and large amplitudes. The sciatic nerve in the contralateral leg showed no hemorrhage or major deformation. Both immediately after the missile impact and after 48 hr the myelin sheaths in the contralateral sciatic nerve showed deformation. Myelin was bulging into the axon, dislocating the axoplasm. The nodes of Ranvier could be exposed to an increased extent. Electron microscopic examination revealed decreased number of microtubules immediately after the trauma, persisting even after 48 hr in the largest axon. Schwann cells showed, especially after 48 hr, signs of damage and swelling. Similar changes, although less extensive, were noticed in the phrenic nerves as well as in unmyelinated axons in both sciatic and phrenic nerves. It is concluded that a high-energy missile hit in the thigh of a pig, caused structurally demonstrable dislocations of myelin sheaths, and disarrangement of cytoskeleton and endoplasmic reticulum in axons as well as other signs of damage. The changes may interfere with the normal functions of peripheral and autonomic nerves.

Pressure wave injuries to the nervous system caused by high-energy missile extremity impact: Part II. Distant effects on the central nervous system--a light and electron microscopic study on pigs

The aim of the present study was to investigate if distant effects could be detected within the central nervous system after impact of a high-energy missile in the left thigh of young pigs. Pressure transducers implanted in various parts of the body of the animal, including the brain, recorded a short-lasting burst of oscillating pressure waves with high frequencies and large amplitudes, traversing the body tissue with a velocity of about that of sound in water (1,460 m/s). The distance between the point of impact and the brain and cervical spinal cord is in the range of 0.5 m. Macroscopic examination revealed that there was no gross brain tissue disruption or visible blood-brain barrier dysfunction. Light microscopic examination demonstrated myelin invaginations in the largest axons and shrinkage of axoplasm. Electron microscopic examination revealed a reduction in the number of microtubules, especially in the larger axons in the brainstem. Disintegration of Nissl substance, i.e., chromatolysis, was noticed after 48 hr in many Purkinje nerve cells in the cerebellum, concomitantly with the appearance of an increased frequency of association between lamellar bodies and mitochondria. Changes could also be observed in the cervical spinal cord and, at reduced frequency and extent, in the optic nerve and in other parts of the brain. These effects were evident within a few minutes after the trauma and persisted even 48 hr after the extremity injury. It is concluded that distant effects, likely to be caused by the oscillating high-frequency pressure waves, appear in the central nervous system after a high-energy missile extremity impact.

Insulin-like growth factor I promotes nerve regeneration: an experimental study on rat sciatic nerve

Insulin-like growth factor I (IGF-I; somatomedin C) has previously been demonstrated, with immunohistochemical methods, to accumulate locally at the site of trauma of an injured peripheral nerve. In the experiments reported here a Y-shaped silicone-chamber system was used to test if local infusion of IGF-I had supportive effects on nerve regeneration. The proximal end of a cut sciatic nerve was inserted into one channel of the Y-shaped chamber and the length and growth direction of the regenerating myelinated axons were evaluated after 1 month. When IGF-I (250 micrograms/ml 0.5 microliters/h) was infused into one channel by an osmotic pump, the length of the regenerating axons increased significantly compared to the control groups with no IGF-I added. In some instances the regenerating axons grew towards the osmotic pump. It is concluded that local infusion of IGF-I at appropriate concentration promotes regeneration of a peripheral nerve. It exerts a neuronotrophic but not a clear chemotactic effect.

Morphological basis for impaired protective efficiency by the nasal mucosa in infants with and without recurrent acute otitis media: a light and electron microscopy study

The structure of the nasal mucosa in biopsy specimens from the inferior turbinate in 'normal healthy' infants (n = 27) was compared with that in age-matched infants (n = 59) with increased frequency of recurrent acute otitis media (RAOM). Light and transmission electron microscopic examination revealed that the healthy infants, i.e., the control subjects, had almost as extensive structural changes in their nasal mucosa as those with RAOM. Only 1 infant in each group was considered to have normal nasal mucosa from a morphological point of view. The high frequencies of structural abnormalities in the nasal mucosa in infants, healthy or with RAOM, is likely to be due to frequent infections causing damage so often and to such high extent that the repair processes became insufficient and thus did not restore the structure of the nasal mucosa. Mucosal lining defects may decrease the resistance to infections, resulting in frequent relapses further adding to the mucosal damage, i.e., a self-ongoing circle.

Insulin-like growth factor I in the developing and mature rat testis: immunohistochemical aspects

The distribution of insulin-like growth factor I (IGF-I; somatomedin C) was mapped in testes of different aged rats by using immunohistochemical techniques. The antiserum used, K 624, has been demonstrated to be specific for human IGF-I, as defined by several criteria. Antibodies to the M1 subunit of ribonucleotide reductase, a key enzyme in DNA synthesis, were used to visualize meiotic and mitotic cells. Cytoplasmic IGF-I-like immunoreactivity as demonstrable during the first two postnatal weeks in spermatogenic cells, in Sertoli cells, and in Leydig cells. The IGF-I-like immunoreactivity decreased in the Sertoli and Leydig cells during the third and fourth postnatal weeks, and in adult rats, only spermatogenic cells showed IGF-I-like immunoreactivity. In mature rat testes, the spermatocytes were strongly immunoreactive. During puberty and adulthood, the spermatogonia expressed subunit M1 ribonucleotide reductase immunoreactivity, whereas no IGF-I-like immunoreactivity could be detected. No extracellular immunoreactivity was observed. We propose that IGF-I and/or IGF-I-like substances, possibly formed by primary spermatocytes, are likely to be involved in differentiation processes, but not in the initiation of cell proliferation in adult testes. The autocrine and/or paracrine action of IGF-I and/or IGF-I-like substances may thus have different action in developing testes than in adult testes. Our results do, however, not allow firm statements about whether IGF-I and related substances exert their actions on Sertoli cells or spermatogenic cells.

Extensive variations in nasal mucosa in infants with and without recurrent acute otitis media. A scanning electron-microscopic study

Biopsy specimens of the nasal mucosa from the inferior turbinate of infants aged 2 to 26 months were examined by scanning electron microscopy. The specimens were obtained from 23 clinically healthy infants and compared with those from 43 infants with recurrent acute otitis media (RAOM). Potentially pathogenic bacteria were isolated from 61% of the control subjects and 90% of those with RAOM. Infants with RAOM had about as extensive alterations as the healthy ones. A single healthy child and one with RAOM had what was interpreted as a normal nasal mucosa; all others showed reduced frequencies of ciliated cells, deformation of cilia, extensive loss of normal mucosal epithelium, and metaplasia in their nasal epithelial lining. Severely damaged area could be seen close to more normal ones. Nasal mucosa in clinically healthy infants rarely had a normal appearance, probably due to frequent infections and the fairly long time needed for the repair process. We proposed that the high frequency of damaged, incompletely healed nasal mucosa may constitute an important factor with regard to the susceptibility to further infections.

Changes in the distribution of insulin-like growth factor I, thioredoxin, thioredoxin reductase and ribonucleotide reductase during the development of the retina

The postnatal development of the rat retina offers good opportunities to follow migration and differentiation of neuroectodermal cells. In this study we have analyzed, by immunohistochemical methods, the distribution of several protein antigens and the trophic peptide insulin-like growth factor I (IGF-I; somatomedin-C). The latter contains disulfide bonds, which in vitro are reduced by the thioredoxin system, i.e. thioredoxin, thioredoxin reductase and NADPH. Ribonucleotide reductase provides growing cells with deoxyribonucleotides, necessary for DNA synthesis, and thioredoxin is an in vitro hydrogen donor. By immunofluorescence IGF-I immunoreactivity was observed throughout the Müller neuroglial cells in the developing retina, but only to a very small extent in the mature retina. Nerve cells showed transient expression of IGF-I during their development. The IGF-I immunoreactivity is likely to be due to local synthesis, since we could demonstrate retinal IGF-I mRNA. Treatment with the transport-blocking agent colchicine caused the Müller glial cells and the retinal pigment epithelium cells to become IGF-I immunoreactive. Thioredoxin and thioredoxin reductase immunoreactivities are confined to neurons and photoreceptor cells in the developing retina. Ribonucleotide reductase subunit M1 immunoreactivity was only observed during the first postnatal week in proliferating neuroectodermal cells. In conclusion, IGF-I and ribonucleotide reductase subunit M1 immunoreactivities are transiently expressed by neuroectodermal cells in the developing rat retina. In contrast, the proteins of the thioredoxin system are demonstrable also in the mature retina.

Somatomedin C in the pancreas of young and adult, normal and obese, hyperinsulinemic mice

Immunocytochemical, immunochemical and RNA-hybridization techniques were used to map the distribution of somatomedin C (Sm-C; insulin-like growth factor I; IGF-I) in the pancreas of young and adult lean and obese mice. The D cells in the islets of Langerhans showed intense cytoplasmic Sm-C immunoreactivity, extending into their processes. Only slight Sm-C immunoreactivity was seen in A and B cells, apparently confined to the plasma membranes. In the exocrine pancreas scattered duct cells were immunopositive. Starvation increased, while feeding decreased the Sm-C immunoreactivity in B cells. RNA-hybridization analyses revealed that roughly the same number of Sm-C mRNA molecules, as calculated per DNA amount in the pancreas, could be demonstrated in young and adult, lean and obese mice. Radioimmunoassay (RIA) determinations of total Sm-C showed that there were about equal concentrations in the pancreas of lean and obese mice. There were marked differences between the liver and the pancreas, in that the RIA Sm-C values for the former were twice those in the latter while, in contrast, the corresponding values for the Sm-C mRNA, i.e. the agent determining the synthesis of Sm-C, were about 100 times higher in the liver as compared to that in the pancreas. We interpret our results as follows: The D cells in the islets form and secrete Sm-C in both young and adult, lean and obese mice, while A and B cells bind, but do not necessarily synthesize this peptide.(ABSTRACT TRUNCATED AT 250 WORDS)

Transient expression of insulin-like growth factor I immunoreactivity by vascular cells during angiogenesis

The present study was undertaken to investigate whether vascular cells show insulin-like growth factor I (IGF-I; somatomedin C) immunoreactivity under normal conditions and/or during angiogenesis in humans and animals, as the trophic peptide IGF-I is considered important for cell growth and differentiation. In adult animals normal blood vessels, i.e., arteries, veins, and capillaries, did not show any IGF-I immunoreactivity. In newborn animals every vascular cell showed IGF-I immunoreactivity; the frequency and intensity thereafter decreased and eventually vanished as the animals approached maturity. Injury of a tissue or organ rapidly induced extensive blood vessel formation and such new blood vessels transiently expressed IGF-I immunoreactivity. Endothelial cells in budding capillaries showed distinct cytoplasmic IGF-I immunoreactivity, as did endothelial cells, smooth muscle cells, and fibroblast in newly formed arteries and veins. In biopsies of human tissue, transient IGF-I immunoreactivity was evident in vascular cells during angiogenesis after injury, as it also was in granulation tissue, skin wounds, and scar capsules around implants. Increased IGF-I immunoreactivity was further demonstrated in vascular cells in biopsies from patients with other changes involving blood vessel formation, e.g., nasal polyps, and in specimens from patients with arteritis, tendonitis, synovitis, Wegener's granulomatosis, idiopathic midline destructive disease, neurofibromatosis (von Recklinghausen's disease), and muscular dystrophy. It is concluded that during angiogenesis, obviously irrespective of inducing factors and mechanisms, vascular wall cells transiently show IGF-I immunoreactivity.

Immunohistochemical demonstration of insulin-like growth factor I in inflammatory lesions in Wegener's granulomatosis and idiopathic midline destructive disease

The immunoreactivity of the trophic peptide insulin-like growth factor I (IGF-I; somatomedin C) was mapped in nasal mucosa biopsies from three patients with Wegener's granulomatosis (WG) and one with idiopathic midline destructive disease (IMDD; idiopathic midline granuloma). Strongly increased IGF-I immuno-reactivity restricted to cells bordering and in vessel walls and in granulomas (WG) was demonstrated, while necrotic and noninflammatory areas were negative. Treatment with steroids and cyclophosphamide reduced the IGF-I immunoreactivity. The abnormally increased IGF-I immunoreactivities in WG and IMDD probably reflects the reactive growth processes in diseased tissue and is not thought to be the primary cause of either disease. IGF-I may be formed locally by cells in and close to the vascular walls in areas with active disease resulting in e.g. vascular growth, granuloma formation, and finally vessel obliteration and necrosis. IGF-I is likely to form, possibly in concert with other trophic factors, a link in the chain of events resulting in the tissue abnormalities in WG and IMDD.

Ultrastructural differences of the interface zone between bone and Ti 6Al 4V or commercially pure titanium

Commercially pure (CP) titanium and Ti 6Al 4V alloy were sputtered onto polycarbonate plastic implants to analyse hard tissue reactions to the two metals. The implants were inserted in the tibial metaphyses of five rabbits. Three months later they were removed and processed for light microscopy (LM) and transmission electron microscopy (TEM) investigations. At the LM level, disordered woven bone was seen in the interface zone of Ti 6Al 4V, whereas organized bone was observed in direct contact with the CP titanium implants. TEM examination of Ti 6Al 4V sections revealed a 500-1000 A thick collagen-free proteoglycan layer compared to 200-400 A for CP titanium. A surface analysis test was performed to compare the magnetron sputtered film with bulk Ti 6Al 4V alloy. This test revealed no major differences between the experimental implant and the bulk alloy. More natural-like tissue reactions were observed to CP titanium than to Ti 6Al 4V alloy.

Pressure wave injuries to rat dorsal root ganglion cells in culture caused by high-energy missiles

A high-energy missile impact in an extremity of an animal creates a shock wave which is rapidly dispersed as a burst of oscillating pressure waves that traverses the entire body causing local, regional, and distant injuries. The present study was performed on dorsal root ganglion (DRG) cells, cultured for 3 weeks, to elucidate the cellular mechanism for damage of nerve cells, using a simplified test system. A model system was developed allowing exposure of DRG cultures to a burst of high-frequency oscillating pressure waves, comparable to those recorded in animals after high-energy missile extremity impact. The pressure waves were induced by impact of a high-energy missile in a rubber tube filled with water, in which nerve cell cultures were kept in a closed rubber glove filled with tissue culture medium. The pressure waves had a duration of 0.5-1.5 ms and a frequency spectrum ranging from 0-250 kHz. Within minutes the neurites showed changes in their microtubules. In addition, varicosities, enriched with tubulin immunoreactive material, became irregularly studded along the nerve cell processes. Scattered DRG cells were initially permeable to the marker complex Evans-blue albumin (EBA), used as an indicator of the ability of the plasma membranes to exclude proteins. After 6 hr, however, almost every DRG neuron was intensely stained by EBA. Concomitantly, there was swelling of the nerve cell cytoplasm and organelles, and, to a variable extent, neurofilament tangles were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Insulinlike growth factor I immunoreactivity in nasal polyps

Nasal polyps from 15 patients were all found to express increased insulinlike growth factor I immunoreactivity. A hypothesis for the formation of nasal polyps is described: macrophages, seen in allergic and infectious reactions, produce and release growth factors, tentatively including insulinlike growth factor I. In enclosed paranasal sinuses this results in an accumulation of insulinlike growth factor I stimulating the growth of both epithelium and blood vessels in the sinuses. The mucosa increasingly bulges out through the ostium after having filled out the sinusity. Continuing growth stimulation is supplied by the inflammatory reaction, endothelial cells in the polyp, and activated macrophages inside or outside the polyp.

Epidermal growth factor and insulin-like growth factor I are localized in different compartments of salivary gland duct cells. Immunohistochemical evidence

Immunohistochemical methods were used to map EGF (epidermal growth factor) and IGF-I (insulin-like growth factor I; somatomedin C) immunoreactivities in salivary glands of adult rodents. Epidermal growth factor is, as is NGF (nerve growth factor), limited in distribution to the granules in granular duct cells in the submandibular gland. Insulin-like growth factor I is, in contrast, cytoplasmic and has a much more widespread distribution. It is seen in intercalated, striated and granulated duct cells as well as in apical parts of excretory duct cells. The parotid and the palatine salivary glands, lacking EGF immunoreactivity, have their IGF-I immunoreactivity similarly distributed as the submandibular gland. Isoproterenol treatment of adult male rats results in rapid and extensive growth of the submandibular and the parotid glands, which double their weights in just a few days. Isoproterenol causes release of granules from the submandibular granular duct cells and decrease in frequency of EGF immunoreactive cells. However, there is no or only minor concomitant changes in the distribution and intensity of the IGF-I immunoreactivity in these duct cells. Our results indicate that the trophic peptides EGF (and NGF) and IGF-I are localized in different compartments in salivary gland duct cells and that divergent pathways control their release.

Somatomedin C immunoreactivity in the Achilles tendon varies in a dynamic manner with the mechanical load

Distribution of the trophic peptide somatomedin C (Sm-C; insulin-like growth factor I; IGF-I) immunoreactivity was mapped in normal Achilles and tibialis anterior tendons. The spindle-shaped tendon fibroblasts showed faint perinuclear staining. Fibroblasts in the paratenon mostly had a more intense IGF-I immunoreactivity, i.e. faint to moderate. When analysing either tendon in detail, areas with more intense IGF-I immunoreactivity could be recognized and seemed to correlate with areas of high mechanical stress. Increased mechanical load induced over 3 days elevated IGF-I immunoreactivity throughout the cytoplasm of tendon fibroblasts. Peak intensity was reached in 7 days, and thereafter the IGF-I immunoreactivity seemed to decrease irrespective of persistent high mechanical load. Training the animals on a treadmill for from 20 up to 60 min per day for 5 days induced after 3-5 days increased IGF-I immunoreactivity throughout the cytoplasm of the tendon and paratenon fibroblasts. Sudden curtailment of loading the Achilles tendon resulted in a marked reduction of the IGF-I immunoreactivity in most fibroblasts within 3 days. After a week only a small number of tendon fibroblasts showed any IGF-I immunoreactivity. The IGF-I immunoreactivity of tendon fibroblasts thus correlates to mechanical loading of the tendon. It is proposed that IGF-I may have a trophic influence on tendon and paratenon cells by autocrine and/or paracrine mechanisms.

Transiently increased insulin-like growth factor. I. Immunoreactivity in UVB-irradiated mouse skin

UVB-irradiation during 3 d for 90, 180, and 180 sec, respectively, at a daily dose of 0.1 and 0.2 joule/cm2, respectively, induced slight inflammatory reactions in the mouse ear. The insulin-like growth factor I (IGF-I) immunoreactivity, normally demonstrable only in scattered basal epidermal cells, rapidly increased in intensity and frequency in the epidermis. After 3 d of UVB irradiation almost all epidermal cells were outlined by IGF-I immunoreactivity in their plasma membrane. The Langerhans cells expressed intense IGF-I immunoreactivity throughout their cytoplasm. The elevated IGF-I immunoreactivity ceased after 5-7 d and was normalized in 3 weeks. The number of Ia positive epithelial Langerhans cells did not seem to be affected by UVB irradiation. It is concluded that the increased IGF-I immunoreactivity is likely to reflect formation of the trophic peptide IGF-I, most evidently by Langerhans cells, in early events of the inflammatory, reactive response of the skin to UVB irradiation.

Ultrastructural demonstration of thioredoxin and thioredoxin reductase in rat hepatocytes

Electron microscopic immunocytochemistry, in conjunction with the immunogold technique, was used to demonstrate the ultrastructural localization of thioredoxin and thioredoxin reductase in rat liver hepatocytes. Gold particles representing thioredoxin and thioredoxin reductase antigenic sites were found throughout the cell, but particularly densely associated with the granular endoplasmic reticulum and the cisternae of the Golgi complex. Label was also distributed over the cytosol and in the chromatin of the nucleus. We conclude that thioredoxin and thioredoxin reductase are present in several different cellular compartments including the nucleus. In particular, the enrichment of thioredoxin and thioredoxin reductase to the endoplasmic reticulum is consistent with functions in protein processing, secretion and the formation of nascent protein disulfides.

Insulin-like growth factor I is a possible pathogenic mechanism in nasal polyps

High concentrations of the trophic peptide insulin-like growth factor I (IGF-I; somatomedin C; SmC) were demonstrated immunocytochemically in all nasal polyps examined, except in areas with necrosis or tissue defects. Most epithelial cells, activated macrophages, and proliferating blood vessels, proved positive, contrasting with the low degree of cellular staining in adjacent normal nasal mucosa. It is proposed that nasal mucosal inflammatory reactions induce local formation and accumulation of IGF-I, which may eventually result in very high IGF-I concentrations in the paranasal sinuses due to the tendency these have to be enclosed, i.e. producing reduced drainage. Assuming that IGF-I constitutes the pathogenic factor, appropriate treatment should be given to reduce the inflammatory reactions and improve drainage.

Neurotropism in nerve regeneration: an immunohistochemical study

A rectangular pseudomesothelial-lined chamber was used to elucidate the hypothesis that in adult rats neurotrophic factors are formed after nerve injury and may influence regeneration of peripheral nerves. The proximal end of a cut sciatic nerve was inserted into one corner of the chamber. In one group of animals the distal end of the cut sciatic nerve was implanted in the diagonally opposite corner of the chamber. In another group we just introduced the proximal end of the sciatic nerve; no distal implant was used. The organization, length and direction of the nerve fibres, regenerating from the proximal end of the sciatic nerve, was visualized immunohistochemically with the aid of antibodies against neurofilaments at 2, 3 and 4 weeks after surgery. When a distal sciatic nerve segment was used, nerve fibres regenerating from the proximal cut end of the sciatic nerve showed an organized growth across the chamber, formed bundles and grew into the diagonally implanted nerve piece. If there was no distal implant, the growth of the randomly directed nerve fibres ceased after about two weeks, resulting in formation of a neuroma-like structure. Increased immunoreactivity of the trophic peptide insulin-like growth factor I (IGF-I, somatomedin C) was demonstrated in the regenerating nerve, most evidently in reactive Schwann cells. It is concluded that a positive neurotropic effect is exerted on growing nerve fibres by injured, reactive peripheral nerve tissue. There could tentatively be a relation between nerve regeneration and local formation of trophic factors.

Cervical dilatation by Lamicel before first trimester abortion: a clinical and experimental study

Twenty women were treated with Lamicel tents for 4 h and 20 women for 16 h before vacuum aspiration in the first trimester of pregnancy. The shorter time of treatment was as effective as the longer time with respect to cervical softening and dilatation. In comparison with an untreated control group, Lamicel treatment was followed by an increased collagenolytic activity and increased sensitivity to prostaglandin E2 of the cervical smooth muscle.

Insulin-like growth factor I in the pancreas of normal and diabetic adult rats

Insulin-like growth factor I (IGF-I, somatomedin C) was mapped by immunocytochemistry in the pancreas of normal and experimentally influenced rats. The polyclonal IGF-I antiserum K 37 was characterized and demonstrated to be specific. In the exocrine pancreas some duct cells showed IGF-I immunoreactivity, other components being negative. The three main endocrine cell types in the islets of Langerhans were IGF-I immunoreactive, most strikingly the D cells. Hypophysectomy resulted in loss of IGF-I immunoreactivity in all three endocrine cell types, i.e. D, A and B cells, while the levels of somatostatin, glucagon and insulin, respectively, remained unchanged. Starvation seemed to increase and feeding to decrease the IGF-I immunoreactivity in the B cells. Cysteamine pre-treatment reduced the normally intense IGF-I and somatostatin immunoreactivities in the D cells. In rats made diabetic with alloxan or streptozotocin, the B cells were irreversibly damaged and lost both their insulin and IGF-I immunoreactivities, while the IGF-I immunoreactivity was increased in A cells; the D cells remained unchanged. The concentrations of IGF-I mRNA in the pancreas were almost equal in normal and alloxan diabetic rats as were the concentrations of extractable IGF-I. We conclude that IGF-I immunoreactive material can be demonstrated in adult animals in all endocrine islet cells, most prominently in the D cells. The expression of IGF-I immunoreactivity is in part under pituitary control. In the adult rat only one islet cell type synthesizes IGF-I immunoreactive material, i.e. the D cells, while, in contrast, the B cells are likely to be a major IGF-I source in fetal and neonatal islets.

Thioredoxin and thioredoxin reductase show function-related changes in the gastric mucosa: immunohistochemical evidence

Low levels of thioredoxin and thioredoxin reductase immunoreactivity were demonstrated immunohistochemically in rat gastric epithelial cells. The intensity was influenced by feeding and fasting, the former resulting in diminished reactions. Acute vagotomy, which abolishes basal acid secretion, resulted in a strongly increased thioredoxin immunoreactivity in all gastric epithelial cells. Stimulation of vagotomized rats with pentagastrin and carbachol reduced the levels of thioredoxin and thioredoxin reductase. Atropine and omeprazole (in stimulated, vagotomized rats) completely inhibited acid secretion, but caused different effects on the thioredoxin levels of gastric cells. Atropine restored the thioredoxin immunoreactivity in most gastric epithelial cells to that of the unstimulated, vagotomized controls. Omeprazole, however, did not reverse the effects of stimulation, and, except in the parietal cells, weaker fluorescence was observed. Similar reaction patterns were seen for thioredoxin reductase, although at lower staining intensities. The results demonstrate that thioredoxin and thioredoxin reductase are expressed in resting cells, and to a lower extent in cells with ongoing secretion.

Differing expression of insulin-like growth factor I in the developing and in the adult rat cerebellum

Insulin-like growth factor I (IGF-I; somatomedin C) is a trophic peptide of importance for the development of several tissues and organs. In the present study we have mapped the cellular distribution and dynamic changes of IGF-I immunoreactivity in the rat cerebellum from its postnatal development to maturity. In vitro hybridization of IGF-I mRNA was used to demonstrate that the IGF-I immunoreactive material was synthesized in the cerebellum during a limited time period of cerebellar differentiation. IGF-I immunoreactivity was absent in primordial nerve cells but was present in neuroglial cells during the first two days after birth and then rapidly increased in intensity in the latter during the next few days. Proliferative nerve cells in the external granular layer did not express IGF-I immunoreactivity, while migrating and differentiating nerve cells as well as neuroglial cells showed intense labelling. Starting about 2 weeks postnatally, the IGF-I immunoreactivity declined, first in the neuroglial cells and eventually in the nerve cells. No IGF-I immunoreactivity could be demonstrated in the normal adult cerebellum. Colchicine pretreatment did, however, enable demonstration of IGF-I immunoreactivity in adult cerebellar nerve cells but not in neuroglial cells. In vitro hybridization revealed IGF-I mRNA in the developing cerebellum but only at very low levels in the adult cerebellum. It is concluded that IGF-I is likely to be a factor of importance for the development and maturation of nerve cells and neuroglial cells in the brain.(ABSTRACT TRUNCATED AT 250 WORDS)

Somatomedin C as tentative pathogenic factor in neurofibromatosis

The distribution of somatomedin C (Sm-C; insulin-like growth factor I; IGF-I) immunoreactivity was examined in biopsies from three patients having the diagnosis neurofibromatosis established on clinical and histopathological criteria. All biopsies showed increased Sm-C immunoreactivity limited to areas with neurofibromas. Schwann cells, adjacent spindle-shaped fibroblast-like cells and newly formed blood vessels were positive. In addition, Sm-C immunoreactivity could be demonstrated in cells in the buccal epithelium. There was faint or no Sm-C immunoreactivity in biopsies from normal tissue of the patients and in specimens from control subjects. We propose that an abnormally increased local production of Sm-C, most likely by Schwann cells, forms a link in the chain of pathogenic events resulting in the disease neurofibromatosis.

Immunohistochemical localization of insulin-like growth factor I in the adult rat

Rabbit antisera against native human insulin-like growth factor I (IGF-I; somatomedin C) or a synthetic tetradecapeptide, representing the carboxyterminal amino acids 57-70 of human IGF-I, were used to map immunohistochemically the distribution of IGF-I immunoreactive material in adult rats. Both antisera were specific for IGF-I, as characterized by immunoabsorption, immunoblotting and radioimmunoassay. There was no cross-reactivity to IGF-II, relaxin or pro-insulin; substances having a high degree of structural homology with IGF-I. High IGF-I immunoreactivity was observed in spermatocytes of the testis; in oocytes, granulosa and theca interna cells of the ovary during early stages of follicle development; in some lymphocytes and in reticular cells of lymphoid and hematopoietic organs; in salivary gland duct cells; in the adrenal medulla, the parathyroid gland and the Langerhans' islets. Chondrocytes in the epiphyseal and rib growth plates and at articular surfaces showed strong IGF-I immunoreactivity. Brown but not white fat cells were stained. Nerve cells in the peripheral and autonomic nervous system showed faint to intense IGF-I immunoreactivity. In contrast, neurons and neuroglial cells in the central nervous system were generally negative; motor neurons being an exception. Erythropoietic, thrombocytopoietic and myeloic cells in the bone marrow showed IGF-I immunoreactivity, but only at defined developmental stages. Hepatocytes showed faint IGF-I immunoreactivity, but became more intensely stained after pretreatment with colchicine. The present results suggest that IGF-I is synthetized by cells in several tissues and organs in the adult rat. There was an apparent association between the localization of IGF-I and cell differentiation.(ABSTRACT TRUNCATED AT 250 WORDS)