Biomedical subjects

L B Dahlin

Publications and source records attributed to L B Dahlin.

At least 19 recordsLinked to original sources

PubMed2005

Injury to the human median and ulnar nerves in the forearm--analysis of costs for treatment and rehabilitation of 69 patients in southern Sweden.

This study analysed the costs of median and ulnar nerve injuries in the forearm in humans and factors affecting such costs. The costs within the health-care sector and costs of lost production were calculated in 69 patients with an injury to the median and/or ulnar nerve in the forearm, usually caused by glass, a knife, or a razorblade. Factors associated with the variation in costs and outcome were analysed. The total median costs for an employed person with a median and an ulnar nerve injury were EUR 51,238 and EUR 31,186, respectively, and 87% of the total costs were due to loss of production. All costs were higher for patients with concomitant tendon injuries (4 tendons). The costs within the health-care sector were also higher for patients who changed work after the injury and if both nerves were injured. Outcome was dependent on age and repair method.

Adolescent↗

PubMed2004

Changes in expression of PACAP in rat sensory neurons in response to sciatic nerve compression.

In the present study, expression of pituitary adenylate cyclase-activating polypeptide (PACAP) in rat dorsal root ganglion (DRG) neurons and sciatic nerve following experimental sciatic nerve compression was studied with the use of quantitative immunohistochemistry and in situ hybridization. Previously, we have investigated changes in PACAP expression after nerve transection and, here, the far more frequently encountered condition of nerve compression injury is examined. Nerve compression was performed unilaterally on the rat sciatic nerve, at mid-thigh level, by application of a narrow silicone tube around the nerve for 3, 7, 14 or 28 days, respectively. We detect a statistically significant upregulation in the number and density of PACAP mRNA expression in both small and large DRG neurons in response to nerve compression. An increased number of PACAP-immunoreactive neurons is also found in the ipsilateral DRG. In addition, PACAP immunoreactivity is observed in the compressed sciatic nerve segment and adjacent nerve tissue after nerve compression. The present findings can be compared with previous studies where we have shown that PACAP expression is upregulated in DRG; in response to peripheral inflammation (primarily in small-medium neurons), and after axotomy (dramatic upregulation in medium-large neurons). In view of the recent findings of an increased PACAP expression in DRG after nerve compression, as well as the previous findings of a modulation of PACAP expression in response to axotomy and inflammation, it is likely that PACAP is also involved in the modulation of the response to peripheral nerve compression.

Animals↗

PubMed2003

What determines the costs of repair and rehabilitation of flexor tendon injuries in zone II? A multiple regression analysis of data from southern Sweden.

The epidemiology and costs of repair and rehabilitation of zone II flexor tendon injuries in 135 patients from the southern part of Sweden were analysed. The little finger was most frequently injured (43%), usually with a knife (46%), and 30% of the injuries were work related. Total median costs within the health-care sector for the injuries were SEK 48,500 (1 EURO=9.23 SEK, 4/1/2002). Costs in other sectors were SEK 93,000. Active mobilization or mobilization with rubber band traction increased costs within the health-care sector (SEK 7400 or SEK 6000, respectively) but improved range of movement (5-7%). Immobilization had a higher complication rate (rupture or need for secondary procedures), which in itself increased total costs by 57%. Non-linear effects were found between age and costs within the health-care sector and the outcome.

Accidents, Occupational↗

PubMed2003

Hand injuries in young children.

Four hundred and fifty five young children (0-6 years old) were treated for hand injuries between 1996 and 2000. Boys (61%) were injured more often and a higher number of injuries occurred during May and September. Fingertip injuries were the most common injuries (37%), and were often caused by jamming in doors at home. Fractures were caused by falls and punches and tendon/nerve injuries by sharp objects. The incidence of hand injuries increased from 20.4/10,000/year in 1996 to 45.3/10,000/year in 2000. Only 4% of the children had complex injuries but these placed a high demand on resources. The incidence of injuries was not higher amongst children from immigrant families.

Age Distribution↗

PubMed2001

Experimental nerve compression and upregulation of CPON in DRG.

Expression of C-terminal flanking peptide of neuropeptide Y (CPON) in DRG and cell proliferation (incorporation of BrdU) in sciatic nerve of rats following chronic nerve compression (silicone tubes with different internal diameters) was studied by immunocytochemistry. An increased number of CPON-positive neurons and cells incorporating BrdU was induced on the compressed side, most pronounced when a tight tube was used, while no cells expressed CPON or BrdU in intact nerves. The increase was transient and declined with time. Nerve compression induces transient cell proliferation in the nerve and expression of CPON in nerve cell bodies, but this is of a lesser magnitude than those following nerve transection.

Animals↗

PubMed2001

C-terminal flanking peptide of neuropeptide Y in DRG following nerve compression.

The C-terminal flanking peptide of neuropeptide Y (CPON) was studied in dorsal root ganglia (DRG) by immunocytochemistry after different recovery periods (3, 6,14 and 28 days) following tourniquet compression of the rat hindlimb (sciatic nerve; 150 or 300 mmHg; 2 h). Compression induced a transient increase in the number of CPON-positive DRG-neurons (the contralateral uninjured side was devoid of CPON-positive cells). The compression-induced increase in CPON was less than that observed in separate rats subjected to sciatic nerve transection. The results show that compression induces regenerative changes in peripheral neurons and that such an injury of the nerve trunk is not limited to the site of the compression but results in the activation of the entire neuron.

Animals↗

PubMed2001

Hyperbaric oxygen treatment has different effects on nerve regeneration in acellular nerve and muscle grafts.

Effects of hyperbaric oxygen treatment (HBO) on nerve regeneration in acellular nerve and muscle grafts were investigated in rats. Nerve and muscle grafts were made acellular by freeze-thawing and the obtained grafts were used to bridge a 10-mm gap in the sciatic nerve on the left and right sides, respectively. Rats were treated with HBO (100% oxygen for 90 minutes at 2.5 atmospheres absolute pressure ATA) twice a day for 7 days. Axonal outgrowth, Schwann cell migration and invasion of macrophages were examined 10 days after the graft procedure by staining neurofilaments, S-100 proteins and the macrophage antibodies ED1 and ED2, respectively. Axonal outgrowth and Schwann cell migration in acellular nerve grafts were superior to that found in the acellular muscle grafts. However, there was no difference between HBO-treated and nontreated rats in acellular nerve grafts. Such a difference was found in acellular muscle grafts concerning both axonal outgrowth and Schwann cell migration from the proximal nerve end. No differences in the content of macrophages or neovascularization (alkaline phosphatase staining) in either of the grafts and treatments were seen. It is concluded that there is a differential effect of HBO-treatment in acellular nerve and muscle grafts and that HBO-treatment has no effect on the regeneration process in acellular nerve grafts, in contrast to fresh cellular nerve grafts where a beneficial effect has previously been reported.

Alkaline Phosphatase↗

PubMed2001

Nerve regeneration enhancement by tourniquet.

The use of tourniquet compression as a non-invasive method to enhance axonal regeneration was assessed in the rat sciatic nerve. One hind limb of the rat was subjected to compression by a tourniquet set at 300 mmHg for 30 or 120 min followed by bilateral test crush lesions performed either directly or after a conditioning interval of 3 or 6 days, with the non-compressed side serving as a control. Axonal regeneration distances were evaluated after 3 days by the pinch reflex test. We found that compression caused an increased outgrowth length of sensory axons compared to the controls. The effect was most obvious after 120 min of compression with a conditioning interval of 6 days. Tourniquet compression has a conditioning lesion effect on peripheral nerve and may enhance nerve regeneration.

Animals↗

PubMed2001

Use of chemically extracted muscle grafts to repair extended nerve defects in rats.

Nerve regeneration, measured as axonal outgrowth, Schwann cell migration, macrophage invasion, and neovascularisation, was compared after repair of a 15 mm gap in rats' sciatic nerves using autologous muscle grafts made acellular either by freezing and thawing or by chemical extraction. Both extracted and freeze-thawed acellular muscle grafts could be used to bridge the defect. However, axons and Schwann cells, as shown by immunohistochemical staining for neurofilaments and S-100 protein, respectively, grew faster into the extracted muscle grafts than into the freeze-thawed acellular muscle grafts and somewhat more axons were observed in the former graft. There were no significant differences between the two graft types with respect to neovascularisation as showed by staining for endothelial alkaline phosphatase, and limited differences concerning invasion of macrophages (ED1 and ED2) as detected by immunocytochemistry. The results showed that chemically extracted muscle grafts could be used to bridge an extended nerve defect and that such grafts in some aspects were superior to freeze-thawed muscle grafts for extended gaps.

Alkaline Phosphatase↗

PubMed2001

Different effect on axonal outgrowth of application of non-absorbable or absorbable tubes around a nerve repair.

We studied regeneration distance of rat sciatic nerve, with the sensory pinch reflex test and immunocytochemical staining for neurofilaments, four to 21 days after transsection, repair, and enclosure of the repair site in either a non-absorbable silicone tube or an absorbable polyglycolic acid (PGA) tube. The size of both tube-types was carefully selected so that they did not compress the repaired nerve. The opposite nerve was repaired and not inserted in a tube (control). The regeneration distances in repaired nerves enclosed in silicone tube were significantly longer than the control side at all time points, a result not seen when PGA tube was used. The number of proliferating non-neuronal cells (incorporation of 5-bromodeoxyuridine (BrdU)) was studied just proximal to the site of nerve repair after six days. Numerous stained cells were seen, but there where no significant differences between the groups. We conclude that outgrowth of sensory axons after transsection and repair of rat sciatic nerve with sutures can be increased by enclosing the site of repair in a silicone tube but not in a PGA tube. The effect is probably not related to the number of proliferative non-neuronal cells.

Absorbable Implants↗

PubMed2001

Effects of hyperbaric oxygen treatment on axonal outgrowth in sciatic nerve grafts in rats.

We studied the effect of hyperbaric oxygen treatment on axonal outgrowth in grafts of sciatic nerves in 40 rats. The sciatic nerve was transsected and a 10 mm long segment from the opposite side was immediately sutured in as a nerve graft. Postoperatively 17 animals were treated with 100% oxygen at 3.2 atmospheres absolute pressure for 45 minutes and the treatment was repeated at four and eight hours postoperatively and then every eight hours until evaluation. At seven days the axonal outgrowth was evaluated by immunohistochemical staining of neurofilaments in the nerve grafts. The axonal outgrowth was significantly longer in animals treated with hyperbaric oxygen. We conclude that hyperbaric oxygen can improve nerve regeneration in sciatic nerve grafts in rats.

Animals↗

PubMed2001

Tissue response to silicone tubes used to repair human median and ulnar nerves.

Silicone tubes of appropriate sizes were used to enclose the injured zone of transsected ulnar and median nerves in the human forearm as an alternative to conventional microsurgical repair of the nerve trunk. A gap measuring 3-5 mm was left intentionally between the nerve ends inside the tube. The clinical early results from a prospective randomised study that compared these two principles have recently been presented. Seven patients (five men and two women), aged 15-49 years (median 20) were reexplored 12-44 months (median 22) after the initial procedure because of local discomfort from the tube in four patients. There was a new nerve structure bridging the former gap and in most cases it was impossible to distinguish the site of the injury. In all cases there was a thin capsule around the silicone tube that microscopically consisted of connective tissue with thin walls and no signs of inflammation, granuloma or macrophages (n = 4), while in two cases a mild foreign body reaction was seen at a single site (n = 1) or at patchy areas (n = 1). These results indicate that after more than one year there is a limited tissue reaction around silicone tubes used to repair median and ulnar nerves in humans.

Adolescent↗

PubMed2001

Vibration-induced hand problems: role of the peripheral nerves in the pathophysiology.

A substantial number of people who are exposed to vibrating hand-held tools develop vasospastic and sensorineural symptoms that may seriously affect the ability to work. Apart from the discomfort of the disease itself, this leads to socioeconomic problems for the patients and high costs for the society. The diagnosis of the neurological symptoms is sometimes difficult and may be misinterpreted as a nerve compressive disorder such as carpal tunnel syndrome, which may also develop. This review summarises our available knowledge about the pathophysiology of the neurological dysfunction with reference to hand problems after exposure to vibrating hand-held tools.

Animals↗

PubMed2001

Neural regeneration along longitudinal polyglactin sutures across short and extended defects in the rat sciatic nerve.

OBJECT: The authors have previously shown that longitudinal sutures without artificial tube support regeneration across a 7-mm gap in the rat sciatic nerve. In the present study, the authors compared this new approach with the use of autologous nerve grafts across short defects and examined whether the approach could be used to support regeneration across extended gaps and whether the interposition of a short nerve segment (the stepping-stone procedure) was applicable in this model. METHODS: Longitudinal sutures were used to bridge 7- and 15-mm gaps in the rat sciatic nerve. Contralateral comparisons were made to nerve autografts in the 7-mm group and to sutures plus a short interposed nerve segment in the 15-mm group. Regeneration was evaluated at 2, 4, and 12 weeks by using immunocytochemical analysis for Schwann cells, neurofilament protein, and macrophages and at 12 weeks also by using histological examination, including morphometry in the distal tibial trunk and tetanic force measurements in the gastrocnemius muscle. CONCLUSIONS: The authors found that the results of regeneration after repair with longitudinal polyglactin sutures across short defects were not significantly different from those produced by the use of autologous nerve grafts. Regeneration, although poor, occurred along sutures across extended gaps and was significantly enhanced by an interposed nerve segment acting as a Schwann cell resource in this model.

Animals↗

PubMed2001

Use of tubes in peripheral nerve repair.

The use of tubes as an alternative to primary nerve suture in fresh nerve transections has been introduced as a biologic approach to nerve injuries, creating optimal conditions for axonal regeneration over a short empty space intentionally created between the proximal and distal nerve ends. The idea may seem controversial and has been criticized using the arguments that silicone in itself may create problems like inflammation and the tube may compress the nerve ends. With the use of appropriately sized tubes for bridging a maximum 5-mm gap in human median and ulnar nerves, the authors have found the technique to be useful and persistent at follow-up examinations for up to 4 to 5 years. In addition, from the intellectual point of view, the principle illustrates the concept by which emphasis is placed on the intrinsic healing capacities of the nerve rather than on the technical skill of the surgeon. The thin mesothelial lining found around the silicone tube lacks primary inflammatory signs at follow-up after 1 year, and no signs of compression are seen. It may be an advantage because it allows sliding of the repair site against the surrounding tissues. Tubes made of bioresorbable material may seem ideal, but they may introduce new problems associated with the resorption process in terms of a substantial unrestricted macrophage invasion, fibrosis, and disorganized axonal growth. For an extended nerve defect, the use of autologous nerve grafts is still the gold standard, because no tubular conduit or other conduit has so far proved equal to autologous nerve grafts, at least not for reconstruction of human median and ulnar nerve trunks. Alternatives other than tubes are currently being developed and investigated. For the future, the use of tubes for repair and reconstruction of nerves may have interesting potentials, because such a structure allows several types of tissue engineering. Various matrices containing, for instance, appropriate cells, factors, or other stimulating agents can be introduced in the tube lumen and can also be incorporated in a slow-release form in the walls of the tube and manipulated. Cultured Schwann cells or other cellular components, with or without manipulated production machinery, are probably the cells of choice for introduction in the tubes. Tubes may thus prove to be interesting alternatives to conventional repair techniques for primary repair of nerves and for reconstruction of segmental defects and for neuroma treatment in the future.

Animals↗

PubMed2000

Reduction of proliferating non-neuronal cells in dried nerve segments partly impairs nerve regeneration.

To determine whether drying of nerve grafts can affect axonal outgrowth and proliferation of non-neuronal cells, nerve segments dried for 0-60 min were used as nerve grafts to bridge a gap in transected rat sciatic nerves. Axonal outgrowth was measured by pinch reflex test and confirmed by immunocytochemical staining of neurofilaments. The proliferation of non-neuronal cells was measured by incorporation of BrdU in the dried nerve segments. Drying of the nerve segment for 60 min reduced the length of axonal outgrowth to 66 and 76% 3 and 6 days, respectively, after the grafting procedure. At that time point the number of proliferating cells was reduced by 51%. It is concluded that the number of proliferating non-neuronal cells is reduced in dried nerve segments which only partly impairs axonal outgrowth. Factors other than Schwann cells are probably important for an optimal mileue for regeneration in nerve grafts.

Animals↗

PubMed2000

Sorbitol and myo-inositol levels and morphology of sural nerve in relation to peripheral nerve function and clinical neuropathy in men with diabetic, impaired, and normal glucose tolerance.

AIMS: Sorbitol and myo-inositol levels and morphology of sural nerve were compared with nerve function and clinical neuropathy in men with diabetic, impaired (IGT), and normal glucose tolerance. METHODS: After neurography of sural nerve and determinations of sensory thresholds for vibration, warm and cold on the foot, whole nerve sural nerve biopsy was performed in 10 men with Type 1 diabetes mellitus, 10 with IGT, and 10 with normal glucose tolerance. Polyol levels were assessed by gas-liquid chromatography/mass spectrometry. RESULTS: Sural nerve amplitudes were significantly lower and sorbitol levels significantly higher in diabetic patients (median (interquartile range)) (3.7 (3.5) microV and 643 (412) pmol/mg protein, respectively) both compared with IGT (11.3 (10.6)microV; P = 0.04 and 286 (83) pmol/mg protein; P = 0.0032, respectively) and normally glucose tolerant (10.0 (11.6); P = 0.0142 and 296 (250) pmol/mg protein; P = 0.0191, respectively) subjects. There were no differences in nerve morphology between the three groups. Nerve myo-inositol levels correlated, however, positively with cluster density (rs = 0.56; P = 0.0054). In diabetic and IGT subjects, sural nerve amplitudes (2.6 (3.8) vs. 12.1 (10.6) microV; P = 0.0246) and myelinated nerve fibre density (MNFD; 4,076 (1091) vs. 5,219 (668) nerve fibres/mm2; P = 0.0021) were significantly lower in nine subjects with clinical neuropathy than in 10 without. CONCLUSIONS: Nerve degeneration (i.e. MNFD) correlated with clinical neuropathy but not with glucose tolerance status whereas nerve myo-inositol levels positively correlated with signs of nerve regeneration (i.e. increased cluster density).

Diabetes Mellitus, Type 1↗

PubMed2000

Bioartificial nerve graft for bridging extended nerve defects in rat sciatic nerve based on resorbable guiding filaments.

A long defect (15 mm) in rat sciatic nerve was repaired with a bioartificial nerve graft composed of a silicone tube and seven synthetic filaments of five types (polyamide, catgut, polydioxanone, and two types of polyglactin, normal and quickly-absorbed) inserted longitudinally into the tube. In all cases in which filaments were used a regenerating bridge was obtained in the tube after three months in contrast to empty silicone tubes, in which no structure was observed. There was a 6%-46% recovery of isometric muscle contractility of the anterior tibial and gastrocnemius muscles with positive pinch reflex test in most cases. Myelinated axons were seen in the regenerating tissue between the filaments but not directly in contact with them, and there were varying numbers of macrophages close to the filaments. Silicone tubes with filaments, regardless of type of filament, induced nerve tissue to regenerate and resulted in functional recovery through a 15 mm nerve gap not achieved with empty tubes. Nerve promoting factors may be applied to the filaments and the model is a valuable tool for further development of artificial nerve grafts.

Animals↗