A Novel Improved Thromboembolism-Based Rat Stroke Model That Meets the Latest Standards in Preclinical Studies.

The animal thromboembolic model of ischemia perfectly mimics human ischemic stroke which remains the leading cause of disability and mortality in humans. The development of new treatment strategies was therefore imperative. The purpose of this study is to improve the thromboembolic stroke model in rats in order to design experiments that use motor tests, and are in accordance with the 3R principles to prevent complications and maintain the same size of the infarct repeatedly. Tail vein dye application, a protective skull mask and a stress minimization protocol were used as additional modifications to the animal stroke model. These modifications significantly minimized the pain and stress severity of the procedures in this model. In our experimental group of Long-Evans rats, a photo-induced stroke was caused by the application of a photosensitive dye (Rose Bengal) activated with white-light irradiation, thus eliminating the need to perform a craniotomy. The animals' neurological status was evaluated using a runway elevated test. Histological examination of the brain tissue was performed at 12, 24 and 48 h, and seven days post-stroke. Tissue examination revealed necrotic foci in the cortex and the subcortical regions of the ipsilateral hemisphere in all experimental groups. Changes in the area, width and depth of the necrotic focus were observed over time. All the experimental groups showed motor disturbances after stroke survival. In the proposed model, photochemically-induced stroke caused long-term motor deficits, showed high reproducibility and low mortality rates. Consequently, the animals could participate in motor tests which are particularly suitable for assessing the efficacy of neuro-regenerative therapies, while remaining in line with the latest trends in animal experimental design.

Effects of 17-ß-estradiol released from shape-memory terpolymer rods on sciatic nerve regeneration after injury and repair with chitosan nerve conduit in female rats.

The aim of this study was to assess 17-ß-estradiol (E2) influence on sciatic nerve regeneration after injury followed by a repair with chitosan conduit in ovariectomized female rats. The study was performed in 2 groups (n = 16) of rats: OVChit - after excision of a fragment of the sciatic nerve, a chitosan conduit was implanted; OVChitE10 group - additionally to chitosan conduit, shape-memory terpolymer rods based on poly(L-lactide-co-glycolide- co-trimethylene carbonate) releasing 17-ß-estradiol for 20 weeks were implanted. The mean number of regenerating axons and mean fiber area were significantly greater in 17-ß-estradiol-treated animals. In this group, the infiltrate of leukocytes was diminished. The presence of 17-ß-estradiol receptors alpha and beta in motoneurons in the spinal cord were discovered. This may indicate the location where 17-ß-estradiol affects the regeneration of the injured nerve. Estradiol released from the terpolymer rods for 20 weeks could enhance, to some extent, sciatic nerve regeneration after injury, and diminish the inflammatory reaction. In the future, 17-ß-estradiol entrapped in terpolymer rods could be used in the repair of injured peripheral nerves, but there is a need for further studies.

Surgical Menopause Impairs Retinal Conductivity and Worsens Prognosis in an Acute Model of Rat Optic Neuropathy.

Deficiency of estradiol during the menopausal period is an important risk factor for neurodegenerative diseases, including various optic neuropathies. The aim of this study was to evaluate the impact of surgical menopause on the function and survival ratio of RGCs in the rat model of ONC (optic nerve crush). We used eight-week-old female Long Evans rats, divided into two main groups depending on the time between ovariectomy procedure (OVA) and euthanasia (two weeks vs. seven weeks), and subgroups-OVA, OVA + ONC, or ONC. Retinal function was assessed with electroretinography (ERG). RGC loss ratio was evaluated using immunolabelling and counting of RGCs. Seven weeks after OVA, the menopause morphologically affected interneurons but not RGC; however, when the ONC procedure was applied, RGCs appeared to be more susceptible to damage in case of deprivation of estrogens. In our analysis, PhNR (photopic negative responses) were severely diminished in the OVA + ONC group. A deprivation of estrogens in menopause results in accelerated retinal neurodegeneration that firstly involves retinal interneurons. The lack of estrogens increases the susceptibility of RGCs to insults.

TXNIP inhibition in the treatment of diabetes. Verapamil as a novel therapeutic modality in diabetic patients.

Loss of pancreatic ß-cell is a critical factor in the pathogenesis of type 1 diabetes and it also occurs in type 2. TXNIP (thioredoxin - interacting protein), also known as vitamin D3-upregulated protein 1, or thioredoxin-binding-protein-2, regulates this process and modulates cellular redox balance. TXNIP is localized primarily in the nucleus, but under oxidative stress it moves to mitochondria, where it interacts with mitochondrial thioredoxin 2. Overexpression of TXNIP induced by hyperglycaemia is typical for diabetes and insulin resistance and leads to apoptosis of pancreatic ß-cell, cardiomyopathy, metabolic disorders and multiple harmful effects. It activates NLRP3 inflamasomme and IL-1ß, a cytokine involved in type 2 diabetes and insulin resistance. TXNIP influences peroxisome proliferator-activated receptor alpha transcriptional activity, expression of glucose transporter-1, nitric oxide production in endothelium and insulin production in ß-cells. TXNIP overexpression leads to diabetic retinopathy, nephropathy, atherosclerosis, it occurs in cancers and autoimmune diseases, while its deficiency protects ß cells. Reduction of TXNIP is an important target in diabetes treatment. In this mechanism insulin, metformin and inhibitors of dipeptydylopeptydase IV are involved. It has been observed that calcium channel blockers (CCB) used in hypertension also inhibit TXNIP expression in cardiomyocytes. L-type channels identification in pancreatic ß-cells revealed that CCB inhibit TXNIP expression also in ß-cells. For the first time, verapamil was distinguished as an agent that not only inhibits TXNIP expression in pancreatic ß-cells, but also enhances ß cell survival and function, and possibly prevents diabetes.

[Potential application of maraviroc in the therapy of neuropathic pain]. / Potencjalne zastosowanie marawiroku w terapii bólu neuropatycznego.

According to International Association for the Study of Pain (IASP) neuropathic pain is defined as a pain caused by a lesion or disease of the somatosensory nervous system. In general population 7-8% adults suffer from chronic pain with neuropathic characteristic. The most common causes include: lumbar radiculopathy, postherpetic neuropathy, HIV infection, autoimmune diseases (multiple sclerosis), metabolic diseases (diabetic neuropathy), stroke or spinal cord injury. Current pharmacotherapy of neuropathic pain has insufficient effectiveness, so comprehension of neuropathic pain mechanism is necessary for research of new therapeutic methods. In the study we verify the analgesic effect of maraviroc (antagonist of the chemokine receptor - CCR5) and its potential role in the treatment of neuropathic pain. In the study we focused on dependency between opioid and chemokine receptors, because of similar structure between this receptors occurs cross-desensitization phenomenon. Chemokine antagonist maraviroc belongs to a group of entry inhibitors, antiretroviral drug. It enhances analgesic properties of opioids by inhibition of crossdesensitization of opioid's receptor. Application of maraviroc with morphine can reduce effective dosage of morphine 2,3 fold. Moreover, research show that prophylactic administration of maraviroc without opioid analgesics suppresses development of neuropathic pain symptoms. It has influence on glial phenotype, decreases secretion of proinflammatory cytokines and increases anti-inflammatory cytokine secretion. Furthermore it decreases expression of chemikine receptor mRNA and chemikine ligand's secreted by microglia and astrocytes as a result of nerve injury. We conclude that maraviroc has immunomodulatory properties, potentiates opioid analgesics effect, and can be used in neuropathic pain therapy as a potential co-analgesic.

Treatment of type 2 diabetes mellitus and risk of pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) is the most common cancer of the exocrine part of the pancreas with poor prognosis. Up to 85% of PDAC patients are diagnosed with diabetes or hyperglycaemia at the time of diagnosis indicating that impaired glucose homeostasis is a common event in this cancer. A mechanism of association between PDAC and diabetes is very complex and still not fully understood. Currently, the various classes of anti-diabetic drugs are used in diabetes treatment. It is possible that specific types of anti-diabetic drugs for diabetes may have different impacts on pancreatic cancer development. Moreover, the intriguing question of whether diabetes can facilitate PDAC development remains unanswered. This paper presents the results of recent studies on the effect of the anti-diabetic treatment used on pancreatic cancer risk in diabetic patients.

Use of ebselen as a neuroprotective agent in rat spinal cord subjected to traumatic injury.

Spinal cord injury (SCI) causes disturbances of motor skills. Free radicals have been shown to be essential for the development of spinal cord trauma. Despite some progress, until now no effective pharmacological therapies against SCI have been verified. The purpose of our experiment was to investigate the neuroprotective effects of ebselen on experimental SCI. Twenty-two rats subjected to SCI were randomly subjected to SCI with no further treatment (n = 10) or intragastric administration of ebselen (10 mg/kg) immediately and 24 hours after SCI. Behavioral changes were assessed using the Basso, Beattie, and Bresnahan locomotor scale and footprint test during 12 weeks after SCI. Histopathological and immunohistochemical analyses of spinal cords and brains were performed at 12 weeks after SCI. Magnetic resonance imaging analysis of spinal cords was also performed at 12 weeks after SCI. Rats treated with ebselen presented only limited neurobehavioral progress as well as reduced spinal cord injuries compared with the control group, namely length of lesions (cysts/scars) visualized histopathologically in the spinal cord sections was less but cavity area was very similar. The same pattern was found in T2-weighted magnetic resonance images (cavities) and diffusion-weighted images (scars). The number of FluoroGold retrogradely labeled neurons in brain stem and motor cortex was several-fold higher in ebselen-treated rats than in the control group. The findings suggest that ebselen has only limited neuroprotective effects on injured spinal cord. All exprimental procedures were approved by the Local Animal Ethics Committee for Experiments on Animals in Katowice (Katowice, Poland) (approval No. 19/2009).

The neuroprotective effect of N-acetylcysteine in spinal cord-injured rats.

BACKGROUND: Spinal cord injury (SCI) is an important cause of impairment of sensory and motor nerve function. It has been shown that free-radical species play an important role in the pathogenesis of acute tissue trauma after SCI. There are no proven pharmacological therapies that provide neuroprotection and stimulate axonal growth after trauma. OBJECTIVES: The aim of this study was to investigate the neuroprotective effect of N-acetylcysteine (NAC) on the regeneration of spinal cord injuries in rats. MATERIAL AND METHODS: A total of 20 male Wistar C rats were subjected to SCI and divided into control and experimental groups. In the control group (n = 10) trepanation and SCI by means of a pressure impactor was performed without any therapy. In the study group (n = 10), 1 dose of NAC was applied intraperitoneally (150 mg/kg b.w.) immediately after SCI, and another one after 24 h. The functional outcome on the Basso-Beattie-Bresnahan (BBB) scale and sciatic functional index (SFI) and morphological features of regeneration were analyzed during a 12-week follow-up. The spinal cords and brains were collected 12 weeks after SCI for histopathological and immunohistochemical analyses. RESULTS: The rats treated with NAC presented some improvement in locomotor activity and spinal cord morphology when compared to the control group. Namely, the hind paw angle of rotation was significantly lower in the NAC group than in the control group. No differences were observed between the control and study groups in terms of interlimb coordination. The area of the main lesion was only slightly decreased in the NAC group as compared to the control group. The length of lesions in the injured spinal cord in the NAC group was diminished in comparison to the control group. The number of FG-positive cells was higher in the NAC group than in the control group. CONCLUSIONS: The study showed that the neuroprotective activity of NAC had limited positive influence on the regeneration of the isolated SCI in rats.

Shape-Memory Terpolymer Rods with 17-ß-estradiol for the Treatment of Neurodegenerative Diseases: an In Vitro and In Vivo Study.

PURPOSE: Estradiol (E2)-loaded poly(L-lactide-co-glycolide-trimethylenecarbonate) (P(L-LA:GA:TMC)) rods with shape-memory were developed for the treatment of neurodegenerative diseases. Usefulness of the extrusion method in the obtaining process was also considered. The influence of structural and surface properties during hydrolytic degradation was developed. The possible therapeutic aspect of rods with E2 was determined. METHODS: The extruded rods were incubated in a PBS solution (pH 7.4, 37°C, 240 rpm). The amount of released E2 in vitro conditions was estimated by UV-VIS method. The following methods in the degradation of rods were applied: NMR, DSC, FTIR, GPC, SEM, and optical microscopy. Changes in water uptake and weight loss were also determined. In vivo study was performed on rats. Measurements of E2 level were performed before and after ovariectomy of rats using ELISA method. A sample of tissue adjacent to the site of the rod implantation was analysed under an optical microscope. RESULTS: A stable and steady degradation process ensured zero-order release of E2. The in vivo study indicated a significant increase in the E2 level in serum after ovariectomy. Moreover, structural and surface features indicated that the extrusion method was appropriate for obtaining E2-loaded rods. CONCLUSIONS: Shape-memory P(L-LA:GA:TMC) rods with E2 are an adequate proposal for further research in the field of neurological disorders.

[Schwann cells in therapy of spinal cord injuries]. / Komórki Schwanna w terapii uszkodzen rdzenia kregowego.

Schwann cells (SC) have a special activity in the repair processes after injury of the nervous system because of the capability of differentiation, migration, proliferation and myelinization of axons. They enhance production of numerous neurotrophic factors, thus creating a permissive environment for axonal regeneration. Experimental studies using SC in neuronal transplants showed that these cells with their basal membrane with adhesion molecules are attractive material for neural prostheses facilitating axon growth. Moreover, SC can produce stable myelin, restoring normal function of the neuron. Transplantations of SC in myelin injury have been used in animal models of multiple sclerosis, Parkinson's disease, and brain and spinal cord injuries. Because the transplanted SC have no ability to migrate within the normal nervous system, in many experiments SC derived from rat embryos were applied. Such cells migrated through normal nervous tissue and co-operated with host cells, their survival was longer, and myelin was not destroyed in multiple sclerosis. Also, fast recovery of motor activity in injured axons in rat spinal cord was observed, especially after transplantation of SC derived from skin progenitor cells or progenitor cells which have a phenotype characteristic for SC. Many authors have reported early apoptosis of transplanted SC, so a more complex repair strategy is needed that combines SC transplantation with other methods in order to achieve longer survival and optimal functional recovery following spinal cord injury.

Concentration of gelatinases and their tissue inhibitors in pancreatic inflammatory and neoplastic tumors and their influence on the early postoperative course.

UNLABELLED: Pancreatic cancer (PC) is the fourth leading cause of death in the world, due to neoplastic disease. Chronic pancreatitis (CP) is a progressive disease leading towards pancreatic fibrosis. The aim of the study was to assess the impact of matrix metalloproteinases 2 and 9 (MMP2 and 9) and their tissue inhibitor (TIMP 1 and 2) concentrations in case of PC and CP tissue homogenates on early treatment results of patients subject to pancreatic resections. MATERIAL AND METHODS: The study group comprised 63 patients, including 25 (39.68%) female and 38 (60.32%) male patients. Group 1 (CP) consisted of 31 patients with CP (F: M = 10/21). Group 2 (PC) consisted of 32 patients with PC (F: M = 15:17). The pancreatic tumor samples were collected from the resected pancreas, being subject to electrophoresis and immunoenzymatic studies. After confirming their activity, MMP2, MMP9, TIMP1, TIMP2 concentrations were determined. Correlation analysis of MMPs and TIMPs concentrations was performed in relation to the following: tumor diameter, age, BMI, hospitalization, duration of symptoms and surgery, blood loss, incidence of perioperative complications. RESULTS: Group differences were presented in terms of: age, BMI, ASA, duration of symptoms, jaundice, tumor diameter, time of operation. There were no differences considering weight loss, blood loss, extent of resection, and hospitalization. Significant MMPs and TIMPs concentration differences between groups were demonstrated. CONCLUSIONS: Comparison of PC to CP tissue samples showed significantly higher levels of metalloproteinases and TIMPs in the former. Positive correlations of MMP1, TIMP1 and 2 with tumor diameter (CP) were observed, and MMP2 with the duration of surgery and blood loss (PC). There was no MMPs and TIMPs concentration levels influence on the incidence of postoperative complications.

Interleukin-1ß increases release of endothelin-1 and tumor necrosis factor as well as reactive oxygen species by peripheral leukocytes during experimental subarachnoid hemorrhage.

In the subarachnoid hemorrhage (SAH) blood mixes with cerebrospinal fluid, what starts immunoinflammatory processes - increased synthesis of proinflammatory cytokines, and formation of reactive oxygen species (ROS), resulting in pre-activation of different populations of peripheral leukocytes. Migration of leukocytes to the brain parenchyma through broken blood brain barrier may produce extra brain tissue injury besides of that resulting from SAH. We examined in adult rats the effect of interleukin-1ß (IL-1ß) neutralization on secretion of cytokines as well as production of ROS in the course of SAH. SAH was produced by injection of 150 µL of autologous arterial blood into cisterna magna. In 50% of animals, IL-1beta activity was inhibited by intracerebroventricular administration of anti-rat IL-1ß antibodies. Ninety minutes or 24 hrs following surgery, blood samples were drawn from the extraorbital plexus and centrifuged to obtain two leukocyte subpopulations - polymorphonuclear (PMN) and mononuclear (MN). The chemiluminescence, a hallmark of ROS synthesis, was measured in PMNs. In supernatants from MNs cultures, concentrations endothelin-1 (ET-1), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were assessed. SAH caused the increase ofn PMNs chemiluminescence as well as the increase of production of ET-1 and TNF-α by MNs but had no influence on IL-6 concentration. Neutralization of IL-1ß resulted in significant decrease of chemiluminescence as well as concentration of both ET-1 and TNF-α, while IL-6 concentration was increased. These revealed an important role of IL-1ß in the activation of peripheral leukocytes in the course of subarachnoid hemorrhage.

APP/SOD1 overexpressing mice present reduced neuropathic pain sensitivity.

There are controversies regarding pain expression in mentally disabled people, including Down syndrome patients. The aim of this study was to examine neuropathic pain-related behavior and peripheral nerve regeneration in mouse model of Down syndrome. Sciatic nerves of double transgenic mice, overexpressing both amyloid precursor protein (APP) and Cu/Zn superoxide dismutase (SOD1) genes, and FVB/N wild type mice were transected and immediately resutured. Evaluation of autotomy and functional recovery was carried out during 4-week follow-up. We found markedly less severe autotomy in transgenic animals, although the onset of autotomy was significantly delayed in control mice. Interestingly, neuroma formation at the injury site was significantly more prominent in transgenic animals. Sciatic function index outcome was better in transgenic mice than in wild-type group. Histological evaluation revealed no statistically significant differences in the number of GAP-43-positive growth cones and macrophages in the distal stump of the transected nerve between groups. However, in transgenic animals, the regenerating axons were arranged more chaotically. The number of Schwann cells in the distal stump of the transected nerves was significantly lower in transgenic mice. The number of surviving motoneurons was markedly decreased in transgenic group. We measured also the atrophy of denervated muscles and found it decreased in APP/SOD1 overexpressing mice. Taken together, in this model of Down syndrome, we observed increased neuroma formation and decreased autotomy after peripheral nerve injury. Our findings suggest that APP/SOD1 overexpressing mice are less sensitive for neuropathic pain associated with neuroma.

Childhood pineal parenchymal tumors: clinical and therapeutic aspects.

The aim of our study was to investigate the correlation of the clinical characteristic of pineal parenchymal tumors in children and adolescent with histopathological diagnosis and patient survival. Records of 27 patients with histologically diagnosed pineocytomas (n=16) and pineoblastoma (n=11) consecutively treated between 1991 and 2001 were reviewed retrospectively to identify factors predictive of aggressiveness. Among analyzed epidemiological, clinical, and radiological factors, we found that independent prognostic indicator in patients with childhood pineal parenchymal tumor was the extent of surgical resection.

Interleukin-1beta plays a role in the activation of peripheral leukocytes after blood-brain barrier rupture in the course of subarachnoid hemorrhage.

Subarachnoid hemorrhage (SAH) develops when extravasated arterial blood enters subarachnoid space and mixes with cerebrospinal fluid. As a result, many pathologies develop, including increase in brain-blood barrier (BBB) permeability and activation of peripheral leukocytes, that in turn augments immuno-inflammatory response, considered as the cause of numerous complications following SAH. In the study, we examined the role of one of major cytokines, interleukin 1-beta (IL-1beta), in the BBB rupture and subsequent migration of leukocytes into central nervous system (CNS) after experimental SAH in adult rats. SAH was produced by injection of 150 uL of autologous arterial blood into cisterna magna. In 50% of animals, IL-1beta activity was inhibited by intracerebroventricular administration of anti-rat IL-1beta antibodies (SAH' groups). Control group consisted of sham-operated rats. Ninety minutes or 24 hrs following surgery, blood samples were taken, then animals were perfused transcardially and whole brains were collected. Three major populations of leukocytes present at brain stem and frontal part of the brain - granulocytes, monocytes/macrophages and lymphocytes - were labeled with appropriate antibodies. S-100B protein concentration in the serum, a marker of BBB permeability, was also measured. Neutralization of IL-1beta activity reduced elevated S-100B level and number of leukocytes found within the CNS, however these changes were not uniformly significant among different subgroups. The results demonstrate an important role of IL-1beta in the BBB damage and leukocyte migration into the CNS subarachnoid hemorrhage.

Application of nanotubes and nanofibres in nerve repair. A review.

Nanoscience is the science of small particles of materials on a nanometre scale in at least one dimension. Nanomaterials can interact with tissues at the molecular level with a very high degree of functional specificity and control. A large group of nanomaterials includes nanotubes, nanofibres, liposomes, nanoparticles, polymeric micelles, nanogels and dendrimers. Such materials can be tailored to react with specific biological systems at a molecular or even supra-molecular level and respond to the cell environment while minimizing undesired side effects. Neuron injuries lead to complex cellular and molecular interactions at the lesion site in an effort to repair the damaged tissue and to regenerate the axon for reconnection with its target organ. Strategies to enhance and stimulate regeneration use various nerve conduits and synthetic guidance devices. A promising strategy for treatment of neuronal injuries is to support and promote axonal growth by means of nanotubes and nanofibres. Nanotubes can be produced from various materials, such as carbon, synthetic polymers, DNA, proteins, lipids, silicon and glass. Carbon nanotubes are not biodegradable and can be used as implants. Moreover, they serve as an extracellular scaffold to guide directed axonal growth. In the review we summarize the results of nanotube and nanofibre application in nerve repair after injury.

[Propranolol--a place in the modern therapy]. / Propranolol--miejsce we wspólczesnej terapii.

The discovery of propranolol in 1964 and its introducing to the clinical practice has been essential for the progress in the diagnostics and therapy of cardiovascular diseases. Indications for the use ofpropranolol are numerous. Propranolol has shown clinical usefulness in the treatment of angina pectoris, hypertension, cardiac arrhythmias, hyperthrophic obstructive cardiomyopathy, mitral stenosis, and pheochromocytoma. It has proved efficacy in the treatment ofhyperthyroidism, porphyria, cirrhosis, migraine and in the therapy of many neuropsychiatric disorders. The article presents a review of the actual clinical applications of propranolol.

[Neutrophins in biology and medicine]. / Neurotrofiny w biologii i medycynie.

Nerve growth factor NGF was the first neurotrophic substance to be identified, isolated, and characterized. NGF is member of a class of substances which has been termed the neurotrophins familly. This family of NGF-related trophic factors includes also brain-derived neurotrophic factor--BDNF, neurotrophin-3, neurotrophin-4/5 and neurotrophin-6 and 7. Each neurotrophin is able to bind to the p75NTR and a specyfic Trk tyrosine kinase receptor. Traditional view is that trophic factors are relesed from target cells, retrogradely transported along their axons, and rapidly degraded upon arrival in cell bodies. But several trophic factors can move anterogradely along axons. NGF-responsive cells are known to belong to the hemopoetic-immune system and to populations in the brain involved in neuroendocrine function. The concentration of NGF is elevated in a number of inflammatory and autoimmune states in conjuction with increased accumulation of mast cells. Neurotrophins can also regulate adult nervous system plasticity by promoting neuronal survival and stimulating nerve regrowth following injury. The potential exists for these neurotrophic factors to be used as therapeutic agents for the treatment neurodegenerative disorders.

Extracts obtained from predegenerated nerves improve functional recovery after sciatic nerve transection.

Gap injuries of peripheral nerves, resulting from trauma or neurosurgical procedures, presage badly, for the presence of the distal stump of the nerve seems to be indispensable for regeneration. The standard grafting method requires a lesion of a healthy nerve, and therefore various substitutional materials are under consideration. The aim of the present work was to examine the recovery of rat sciatic nerves after supplying 10-mm-long gaps with an autologous connective-tissue chambers filled with fibrin only or fibrin and various neuroactive substances (brain-derived neurotrophic factor (BDNF), extracts from predegenerated or non-predegenerated nerves). The nerves were allowed to regenerate for 16 weeks. Recovery was measured functionally using the sciatic functional index, and by comparing the weight ratios of calf muscles. The histologic features of regeneration were assessed by counting the number of acetylcholinesterase-positive nerve fibers present inside implanted chambers. We found that chambers filled with fibrin and predegenerated peripheral nerve extracts or BDNF supported functional nerve regeneration much more strongly than chambers filled with fibrin only or fibrin and non-predegenerated peripheral nerve extracts. We conclude that autologous connective-tissue chambers filled with fibrin and predegenerated peripheral nerve extracts or BDNF seem to be a promising tool in peripheral nerve gap injury treatment, with likely clinical implications.

Influence of a new propranolol analogue on the rabbit myocardium in vitro.

Experiments with electrophysiology of the heart have been essential for the progress in diagnostics and pharmacotherapy of cardiovascular diseases. The aim of the study was to establish the influence of a new propranolol analogue on mechanical and bioelectrical activity of the rabbit heart in vitro. In the experiment, propranolol (1-isopropylamino-3-[1-naphthoxy]-2-propanol hydrochloride) and its newly synthesized analogue (1-[1,1-dimethyl-ethyl-amino]-3-[1-naphthoxy]-2-propanol hydrochloride) were used. Atrial trabecules were cut from right rabbit atrium. Each preparation consisted of cardiomyocytes and sino-atrial node cells. Preparations were stimulated with square pulses of direct current at a voltage of 20V, rate of 2 Hz and 1 ms duration. Propranolol and its analogue were applied at gradded concentration 10(-2) M, 10(-3) M, 10(-4) M, 10(-5) M, 10(-6) M and 10(-7) M. Mechanical (force of contraction, time of contraction and relaxation) and bioelectrical (amplitude and duration of action potentials) activities were examined. Bioelectrical activity of preparations was recorded using intracellular microelectrodes. LD(50) for new analogue was determined. Analogue diminished force of contraction and shortened time of contraction and relaxation of myocardium and decreased amplitude and duration of action potentials in sino-atrial node cells. It influenced mechanical and bioelectrical parameters to lesser degree than propranolol.