Biomedical subjects

B Gerdin

Publications and source records attributed to B Gerdin.

At least 91 records · Page 5Linked to original sources

PubMed1991

Nervous influence on traumatic vasospasm in the rabbit ear artery.

The effects of partial denervation, partial denervation with additional nervous blockade with bupivacaine, and total denervation achieved by amputation and replantation of the ear on traumatic vasospasm were studied in the rabbit. The central ear artery was exposed and compressed in a standardized fashion. The inner diameter was determined by in vivo microscopy using transillumination with cold light. The resulting spasm was assessed in terms of its duration, intensity (reduction of initial diameter), and severity (integrated change in diameter over time). None of the types of denervation had any influence on the vasospasm. The results suggest that the vasospasm is a local phenomenon of the vascular smooth muscle and is not modified by the nervous system.

Alfaxalone Alfadolone Mixture↗

PubMed1991

Leucocyte depletion does not affect post-ischaemic nerve cell damage in the rat.

Leucocytes play an important role in inflammation and immunologic responses. They might be of special significance under pathophysiological conditions of the brain i.e. ischaemia or stroke. It has been shown that neutropenic animals undergoing reversible ischaemia show higher post-ischaemic blood flow, suggesting improved post-ischaemic perfusion. In this study it was investigated therefore, whether polymorphonuclear leucocytes contribute to the nerve cell loss in the hippocampus after a reversible period of ischaemia. Rats were made neutropenic with a specific anti-serum against rat polymorphonuclear leucocytes yielding leucocyte counts less than 10% of normal. The animals were then subjected to 15 min reversible forebrain ischaemia. Quantitative histology was performed after a survival period of 7 days. Nerve cell counts in the frontal cortex and in the CA1 and CA3 sectors of the hippocampus did not reveal any differences between neutropenic rats and animals with normal leucocyte counts. From the results it might be concluded that neutrophils do not significantly contribute to the selective post-ischaemic nerve cell damage in the rat.

Acid-Base Equilibrium↗

PubMed1991

Modulatory effects of topically administered lidocaine and pentobarbital on traumatic vasospasm in the rabbit ear artery.

The effect of topical administration of 2 or 20% lidocaine and of 3% pentobarbital on traumatic vasospasm was studied in the central ear artery of the rabbit. The inner diameter of the artery was measured by in vivo microscopy. Vasospasm was induced by a standardised pinch of a 3.2 mm long arterial segment and lasted for 10-20 min. The drugs were given locally at maximal spasm, 1 min after spasm induction. All treatments caused prompt resolution of the vasospasm. This was followed by a plateau phase when the vessel diameter was reduced to about 60% of the initial pre-spasm value as a result of drug-induced vasoconstriction. The vasoconstriction lasted between 40 min and 24 h, depending on the treatment. Twenty per cent lidocaine was most effective, but caused thrombosis in microvessels surrounding the central ear artery. It is concluded that topical lidocaine and pentobarbital are both effective in resolving traumatic vasospasm but should only be used after careful consideration, since they also cause a general decrease in vascular diameter.

Animals↗

PubMed1991

Determination of biomechanical characteristics of restrictive adhesions and of functional impairment after flexor tendon surgery: a methodological study of rabbits.

Formation of restrictive adhesions is one of the main obstacles in rehabilitation following hand surgery. Most experimental work, however, involves only a macroscopic and/or histologic evaluation of the amount of adhesions, and their functional characteristics are poorly described. The aim of this study was to develop an experimental technique for characterization of the biomechanical properties of the finger-tendon unit. An instrument was developed for continuous and simultaneous recording of tensile load, tendon excursion and angular rotation in the distal interphalangeal joint of rabbit digits. Utilizing this instrument, it was revealed that the first 50 degrees of flexion required virtually no tensile load either in unoperated digits or immediately after tenorrhaphy. Thereafter, the load required to obtain further flexion was progressively increased. The strength of adhesions, determined 2 weeks after tenorrhaphy, was best expressed as the maximum tensile load recorded before 50 degrees of flexion was reached. This measurement could also be used to register the strength of the tendon repair and to detect partial tendon rupture during the measurement. The technique allows both adequate measurements of the strength of the adhesions and of the tendon gliding ability after flexor tendon surgery.

Animals↗

PubMed1991

Blocking weight-induced spinal cord injury in rats: therapeutic effect of the 21-aminosteroid U74006F.

The effect of the 21-aminosteroid U74006F on neurologic recovery after a spinal cord compression trauma was investigated in rats. The compression was induced by a blocking weight technique, in which a 35 g (moderate injury) or a 50 g (severe injury) weight was applied for 5 minutes to an 11 mm2 plate over the midthoracic spinal cord. One hour after trauma, the severely injured animals were treated either with U74006F, 3 mg/kg, methylprednisolone, 30 mg/kg, or vehicle, whereas the moderately injured animals received U74006F, 3 mg/kg or vehicle. Neurologic hind limb function was evaluated by the inclined plane technique. On day 1 after trauma, subtotal paraparesis occurred in the 35 g group treated with vehicle (31 +/- 1 degrees, mean +/- SEM) on the inclined plane vs 64 +/- 1 degrees before trauma) and complete paraplegia in the 50 g group (22 +/- 1 degrees). Treatment with U74006F resulted in less hind limb weakness in the 35 g group (42 +/- 2 degrees) but had no beneficial effect in the 50 g group (25 +/- 2 degrees). Neurologic function gradually improved in the 35 g groups over the 9-day observation period. However, those animals treated with U74006F were significantly better over the entire period. In the 50 g group, no recovery from paraplegia was noted over the 4 day observation period in any of the three groups. These results suggest that after weight-induced spinal cord trauma, U74006F is associated with improved neurologic function in moderately injured, but not severely injured animals.

Animals↗

PubMed1991

Evidence that LS-2616 (linomide) causes acute rejection of rat allografts protected by cyclosporine but not of long-term surviving allografts.

The immunomodulator LS-2616 (Linomide) induces rejection of cyclosporine-protected rat cardiac allografts. The aim of this study was to characterize this rejection in the presence of CsA and to test LS-2616 in other models of permanent graft acceptance in the rat. PVG rat hearts were transplanted heterotopically to Wistar/Kyoto (Wi/Ky) rat recipients on day 0. The recipients were treated orally on days 0-9 with CsA (10-40 mg/kg) and/or with LS-2616 (2.5-160 mg/kg) starting at different times (day -7 -+5) until the day of complete rejection. The addition of LS-2616 (day -1--stop) to CsA (10 mg/kg) resulted in a dose-dependent antagonism of the immunosuppressive effect of CsA with daily doses of 2.5-160 mg/kg. Furthermore, the results were similar, irrespective of whether LS-2616 treatment (160 mg/kg) was started on day -7, -1, +1, +3, or +5. LS-2616 (160 mg/kg) pretreatment of the recipient for 7 days before transplantation was considerably less effective. CsA (20 mg/kg) for 14 days after a PVG to DA transplantation resulted in permanent graft survival. This was not abrogated by LS-2616. Neither was rejection induced in long-term surviving grafts of RT1.C incompatible Lewis recipients. Our data suggest that LS-2616 activates already stimulated and sensitized T cells that are otherwise controlled by CsA.

Animals↗

PubMed1991

MK 801, an OBS N-methyl-D-aspartate channel blocker, does not improve the functional recovery nor spinal cord blood flow after spinal cord compression in rats.

Damage to the central nervous system is followed by local release of excitatory amino acids, e.g. glutamate. These have been claimed to increase the metabolic need of already hypoxic neurons, and thereby to promote cell death. To investigate whether N-methyl-D-aspartate (NMDA) receptor-mediated mechanisms are involved in the damage consequent to spinal cord injury, 20 rats were exposed to 5-min compression of the thoracic spinal cord produced with a load of 35 g on a 2.2 x 5 mm sized plate. One group of animals was given a noncompetitive NMDA channel blocker, MK-801, in a dose of 10 mg/kg b.w and one group saline alone. The neurologic function was evaluated on the inclined plane for 4 days when spinal cord blood flow (SCBF) was measured with the 14C-iodoantipyrine autoradiographic technique. One day after trauma the animals in both groups were paraparetic and exhibited a significantly decreased capacity angle at the inclined plane test (about 35 degrees compared with about 63 degrees before compression). Thereafter, the motor function improved slightly, but to a similar extent in the two groups. On Day 4, gray and white matter SCBF was similar in the two groups. The results indicate that MK 801 in the dose used does not prevent the development of neurologic dysfunction or the reduction in SCBF after spinal cord compression.

Animals↗

PubMed1991

Localisation of hyaluronan in the human intestinal wall.

By using biotin labelled proteoglycan core protein and an avidin enzyme system, hyaluronan (hyaluronic acid) was visualised in specimens of human jejunum. Intense staining for hyaluronan was seen in the loose connective tissue of the villi and of lamina propria while the epithelial layer was unstained. The muscularis mucosae showed only faint staining. The accumulation of hyaluronan in the subepithelial layer of the jejunal mucosa indicates that the previously reported high jejunal secretion of hyaluronan is due to passive diffusion from the subepithelial interstitium. The physicochemical characteristics conferred by hyaluronan may be important for the villi function.

Biotin↗

PubMed1991

Accumulation of hyaluronan and tissue edema in experimental myocardial infarction.

Experimental myocardial infarction was induced in rats. The myocardial accumulation of hyaluronan (HA) and water during the development of infarction was measured. The extractable HA content of the infarcted area increased progressively from day 1 and on day 3 reached a threefold increase compared with the HA amounts in myocardium of sham operated controls. The relative water content of infarcted areas also increased progressively reaching a maximum value by day 3 and was strongly correlated with the HA accumulation. Affinity histochemistry visualized a thin rim of HA in the endoperimysium in healthy myocardium. By day 2 an interstitial edema with inflammatory cells was apparent. The widened endoperimysium stained extensively for HA. By its water-binding ability, interstitial accumulation of HA will contribute to the interstitial edema in infarcted myocardial tissue. An interstitial edema is likely to influence the electromechanical characteristics of the myocardium and facilitate reentry phenomena due to a loss of contact between muscle cells. The edema also induces an increased extracellular pressure and an altered myocardial wall compliance that might impair myocardial microcirculation. The findings are relevant to an understanding of the beneficial effect of hyaluronidase treatment in limiting cellular damage during myocardial ischemia.

Animals↗

PubMed1991

Hyaluronic acid in flexor tendon sheath fluid after sheath reconstructions in rabbits. A comparison between tendon sheath transplantation and conventional two stage procedures.

Because the synovial environment has been suggested to be important in limiting the number of postoperative adhesions after flexor tendon surgery, and a high concentration of hyaluronic acid is a characteristic feature of synovial fluid, we have examined the hyaluronic acid concentrations in fluid collected from different kinds of reconstructed flexor tendon sheaths in rabbits. The hyaluronic acid concentration in normal rabbit flexor tendon sheaths was similar to that in normal human sheath and joint fluid. Rabbit tendon sheaths restored by autologous sheath grafts and partial pseudosheaths contained similar or somewhat lower hyaluronic acid concentrations, whereas in complete pseudosheaths the concentrations were considerably lower. The data suggest that tendon sheath reconstructions should consist at least partly of synovial membrane so that they are as similar as possible to normal synovial membrane.

Animals↗

PubMed1991

Sodium hyaluronate increases vascular ingrowth in the rabbit ear chamber.

The rabbit ear-chamber model was used to study the effect of sodium hyaluronate (NaHe, Healon) on the rate of ingrowth of vascular structures of healing granulation tissue. The chamber area covered by granulation tissue was determined by in-vivo microscopy at regular intervals during a period of 32 days. Daily injections of 1% NaHe into the ear chamber, 50 microliters from day 0 to day 7 and 25 microliters from day 8 to day 21, significantly inhibited ingrowth as observed between days 20 and 26, compared with buffer-injected controls. There was no difference between the latter and non-injected chambers. Intermittent injections of 1% NaHe, 50 microliters on days 1 and 5 and 25 microliters on days 9, 13 and 22 significantly increased the ingrowth as observed between days 6 and 18. It was noted that wound macrophages internalized fluorescein-labelled NaHe. The inhibitory effect of daily injections on angiogenesis was probably due to physical hindrance caused by the NaHe. The stimulatory effect of intermittent administration of NaHe on angiogenesis may have several explanations, including activation of macrophages and their release of angiogenetic factors.

Animals↗

PubMed1991

Effect of cerebral ischemia on hypotension-induced increase in plasma vasopressin and hepatic glycogen concentration in the rat.

The effect of cerebral ischemia on the vasopressin response to hemorrhagic hypotension and on the hepatic and muscular glycogen mobilization was studied in rats. The addition of cerebral ischemia to the hemorrhage required withdrawal of significantly more blood to lower mean arterial pressure (MAP) to 50 mmHg but not if combined with ganglionic blockade. The increase in plasma vasopressin concentration during hypotension was not significantly different in rats with and without concurrent cerebral ischemia. Ganglionic blockade blunted the vasopressin response. Thus cerebral ischemia in fact attenuated the vasopressin response to hemorrhage. One hour after the insult, the hormone concentration in rats exposed to combined cerebral ischemia and hemorrhagic hypotension without ganglionic blockade was still above control levels and higher than in all other groups. Concomitantly the hepatic but not the muscular glycogen concentration in these rats was significantly lower than in the other groups.

Animals↗

PubMed1991

Oxygen-free radicals (OFR) and circulatory shock.

During the past decade a large body of information has been collected showing that formation of short-lived highly reactive metabolites (i.e., radicals) constitutes an important principle of tissue injury. There are several sources of information which suggest that radicals are formed in connection with tissue ischemia and shock, and they may then cause damage to cells and contribute to the pathophysiology of ischemia and shock. In the present review we attempt to discuss how radicals damage tissue as well as the data which suggest that radicals are causing tissue injury in shock.

Animals↗

PubMed1990

Hyaluronic acid accumulation and redistribution in rejecting rat kidney graft. Relationship to the transplantation edema.

By using biotin-labeled proteoglycan core protein and an avidin-enzyme system, hyaluronic acid (HA) was visualized in rat kidney. In the normal kidney, HA was localized in the extracellular space of the inner medulla and increased markedly towards the papillary tip. No staining for HA was seen in the interstitial tissue of the cortex or the outer medulla. During the development of rejection of allogeneic renal grafts, a progressive increase in accumulated HA was seen in the interstitial tissue of the cortex and outer medulla. The extractable amounts of HA increased, on average, 40 times in the cortex and outer medulla; no increase was measured in the inner medulla and papilla. The relative water content of the cortex and outer medulla also increased progressively and correlated with the HA accumulation. The extractable amounts of HA in syngeneic grafts increased by day 2 and then leveled off, indicating that surgical trauma may induce some transient HA accumulation after transplantation. Interstitial accumulation of HA, a glycosaminoglycan with unique water-binding qualities, would presumably influence water transport and osmotic activity and should thereby be implicated in the normal papillary function, but also in the development of the interstitial edema of the cortex and outer medulla during rejection of renal grafts.

Animals↗

PubMed1990

An in vivo method for studies of traumatic vasospasm.

A study was undertaken to develop a model for investigations of traumatically induced vasospasm. The left ear of the rabbit was denervated under short anesthesia. With the animal under light sedation, spasm of the central ear artery was repeatedly induced with a clip applying forceps. To evaluate the vasospasm, the vessel was transilluminated with cold light, and the internal diameter was continuously measured. The spasm was assessed in terms of its duration, intensity (reduction of initial diameter) and severity (integrated change in diameter over time). Repetitive application of the forceps on the same vessel segment shortened the spasm duration. With prolonged pinch duration, the spasm duration was lengthened. The preparation was stable for at least 3 hours. This model was effective for manipulating small vessels and producing spasm and is of potential value for studying the treatment of vasospasm by topical local intra-arterial and systemic methods.

Animals↗

PubMed1990

The polymorphonuclear leukocyte: has it a role in fracture healing?

The aim of the present study was to assess whether the presence of polymorphonuclear leukocytes in the first stage of fracture repair was of any importance. In anesthetized male Wistar rats, a transverse osteotomy was performed at midshaft in one femur and immediately stabilized by an intramedullary Kirschner nail. The animals were allowed unprotected weight bearing immediately. Nine animals were made neutropenic before operation by injection of a specific rat polymorphonuclear leukocyte antiserum (antineutrophil serum, ANS) raised in sheep. The number of circulating polymorphonuclear leukocytes were kept below 20% of their normal value for 72 h postoperatively by intraperitoneal injections of ANS every 12 h. Control animals were injected with the same amount of normal sheep serum (NSS). All animals received cefuroxime (100 mg/kg day) concomitantly with the ANS injections. Six weeks after operation the animals were killed, the amount of callus formation was measured, and the bones were radiologically examined. The nails were then removed and both the healing fractures and the nonoperated femurs mechanically tested for bending. There were no differences in the amount of callus measured or in radiological healing. However, there was a significantly higher bending moment in femurs from animals treated with ANS than in those given NSS (P less than 0.02). No differences were observed in rigidity or total energy absorption.

Animals↗

PubMed1990

Superoxide dismutase does not prevent delayed hypoperfusion after incomplete cerebral ischaemia in the rat.

Local cerebral blood flow (1CBF) was measured autoradiographically 60 minutes after 15 minutes of forebrain ischaemia in rats treated with superoxide dismutase (SOD) before (50 mg.kg-1 body weight) or at the end of the ischaemia period (4 mg.kg-1 body weight). Incomplete forebrain ischaemia was produced by a combination of common carotid artery occlusion and bleeding to a mean arterial blood pressure of 50 mmHg. During ischaemia the 1CBF values in cortical areas were less than 3% of the preischaemic values and treatment with SOD prior to ischaemia did not influence 1CBF during ischaemia. Sixty minutes after termination of cerebral ischaemia the 1CBF values were decreased to between 40 and 60% of values found in control animals. Neither form of treatment improved the postischaemic cerebral blood flows. The results imply that postischaemic flow disturbances in the brain may not be due to extracellular superoxide production.

Animals↗

PubMed1990

Neuropathological changes and neurological function after spinal cord compression in the rat.

As part of a series of experimental investigations of the effects of various pharmacological agents on the outcome of compressive spinal cord trauma in the rat, the time course of the cell changes in the cord at the site of and distal to the compression was studied at the light microscopic level. The degree of compression used with the present model results in a transient paraparesis that recovers almost completely over a period of 3 weeks as judged by the inclined plane technique. The most significant morphological findings were as follows. Initially (1 and 24 h after the impact) there was pronounced swelling and hemorrhage at the compression site, chiefly in the gray matter of the cord. On day 4 there was severe necrosis in the same region, with numerous macrophages and leukocytes. Rats killed after 21 days showed either minor residual signs of necrosis or essentially normal tissue architecture. Surprisingly, necrosis with delayed onset also developed in the dorsal columns, involving the pyramidal tracts. This necrosis was detected in animals killed after 9 and 21 days but not in those observed after 4 days or earlier. The longitudinal tracts of the white matter showed reduced staining in paraffin sections of the compression site. Epon sections revealed splits in the myelin sheaths and enlarged periaxonal spaces as early as 1 h after the impact. The alterations in the longitudinal tracts persisted throughout the 21-day observation period and extended down to L2-L4. There was gradual functional recovery, documented by the inclined plane test. Preinjury values were almost reached on day 21, although the cord still showed some morphological damage. In individual animals, no relation was found between degree of function as tested by inclined plane and extent of morphologic injury. Additional functional and morphological methods obviously are needed in future investigations of the effects of treatments on the outcome of compressive spinal cord injury.

Animals↗