Experimental hyperthyroidism enhances the regeneration of central neurites promoted by peripheral nerve grafts in the hippocampus.

The aim of the present paper was to ascertain whether experimental hyperthyroidism promotes the regenerative action of predegenerated peripheral nerve grafts implanted into the transected hippocampus. Hyperthyroidism was induced by subcutaneous injections of T4. Autologous peripheral nerve grafts were implanted immediately, 7 and 35 days following transection of the sciatic nerve. Cells extending their neurites into the grafts were traced by means of horseradish peroxidase conjugated with fluoresceine isothiocyanate (FITC-HRP). Fluorescence microscope examination revealed that experimentally induced hyperthyroidism considerably enhanced the regenerative influence of peripheral nerve grafts. This effect was particularly pronounced in hyperthyrotic animals treated with either nonpredegenerated or 35 day predegenerated nerve grafts.

Neurotrophic effect of submicrosomal fractions obtained from pre-degenerated peripheral nerves.

Submicrosomal fractions obtained from pre-degenerated distal stumps of sciatic nerves were implanted by means of connective tissue chambers into the injured hippocampus for 8 and 18 weeks. The nerve stumps were allowed to pre-degenerate for 7, 28 and 35 days. The neuronal outgrowth was examined by means of FITC-HRP injected into the chamber. Eight weeks postoperatively the greatest number of traced cells was present in brains treated with the fraction obtained from nerves pre-degenerated for 7 days. Eighteen weeks following implantation the greatest number of FITC-HRP positive cells was found in brains grafted with the fraction from nerves pre-degenerated for 35 days.

Time-dependent regenerative influence of predegenerated nerve grafts on hippocampus.

Our previous studies have revealed that the predegeneration facilitated the neurite outgrowth from hippocampus following the peripheral nerve grafts implantation. The aim of the present work is to find whether the stimulative power of peripheral nerve grafts depends on the time lapse after the transection. Autologous predegenerated distal stumps of the rat sciatic nerves were implanted into the hippocampus on the 7th, 14th, 28th, and 35th day following the transection. Six weeks later, horseradish peroxidase conjugated with fluorescein isothiocyanate was injected into the graft and frozen sections of brains were made. Fluorescence microscope examination has shown that FITC-HRP labeled cells were present among the hippocampal neurons in all the brains under examination, excluding these grafted with 14-day predegenerated peripheral nerves. The FITC-HRP labeled neurons were particularly numerous when the 7- and 35-day-old predegenerated stumps were used as grafts.

Autologous connective tissue bars as vehicles for the administration of growth-influencing substances to the brain.

One of the main problems in the introduction of growth factors or other substances into the CNS is that most of these do not pass the blood-brain barrier, and so they have to be delivered directly to the target cells. Recently, different methods of intracerebral administration have been introduced such as release of drugs from polymer matrix or hollow polymer fibres, implantation of solution-soaked gel foam pieces or genetically modified cells secreting growth factors. In our studies on regeneration in CNS, the problem of introducing active substances into the brain arose. For this reason we elaborated a new method for the administration of soluble factor by means of autologous connective tissue chambers filled with fibrin. This method is particularly suitable in studies in which the visualization of the regrowth of nerve fibres is one of the main purposes. Presence of an active substance inside the chamber fibres to grow in the direction of the chamber and such fibres can be visualized here. Such visualization is impossible while using other methods of trophic substance delivery into the CNS, e.g. intraventricular steel cannula connected to an osmotic minipump, because there is neither space nor appropriate milieu to allow the fibres' ingrowth. Retrograde tracing methods allow to establish the cells of origin of these fibres. This method is inexpensive, simple and adaptable to histological procedures.

Postmicrosomal protein fractions from short-time-predegenerated rat sciatic nerve.

The postmicrosomal protein fraction obtained from distal stumps of rat sciatic nerves at 0-6 days following transection were investigated by means of one- and two-dimensional electrophoresis. In all experimental groups, total amount of protein was significantly higher than in the control group. Proteins were resolved into 27 bands after SDS-PAGE. Their molecular weights ranged between 16.2 and 335.4 kDa. Eleven fractions displayed significant quantitative differences. After 2-D-electrophoresis, the pI of the proteins ranged from 4.2 to 7.4. They were resolved to 28 molecular masses from 13.5 kDa to 335.4 kDa. The greatest numbers of fractions (90-109) were observed on the 3rd, 4th, 5th and 6th day after nerve transection. Thus, during first 6 days after transection intensive changes in protein fraction content and composition take place in the distal stump of peripheral nerve. These processes seem to be most prominent on the 4th day after lesion. Results confirm our earlier in vivo findings.

[Occupational exposure of workers in chemical factors and selected parameters of the respiratory system]. / Narazenie zawodowe pracowników zakladów chemicznych a wybrane parametry ukladu oddechowego.

Workers employed in chemical factories are chronically exposed to harmful substances present in the air of the occupational environment. The aim of this paper was to find out whether this situation produces adverse effects on the respiratory system despite the observance of admissible concentrations of toxic substances in the air. Spirometric values such as FVC1 and FEV1%FVC were measured in 647 workers. It was found that workers in some departments (power station and polystyrene) showed restrictive and obturative disturbances of ventilation. In other departments workers exhibited less expressed respiratory disorders. Adverse effect of smoking and long period of employment on the respiratory system of workers was also revealed. These results indicate that apart from substances present in the occupational environment there are other factors which affect as well the respiratory system of persons employed in the chemical industry.

Concentrations and activities of metalloproteinases 2 and 9 and their inhibitors (TIMPS) in chronic pancreatitis and pancreatic adenocarcinoma.

UNLABELLED: Pancreatic cancer (PC) and chronic pancreatitis (CP) are still significant problems. The aim of this study was a comparative analysis of the activity and concentrations of matrix metalloproteinases 2 and 9 and the concentrations of their tissue inhibitors (TIMP 1 and 2) in the PC compared to CP tissue homogenates. The study was performed in a group of 63 patients with pancreatic cancer or chronic pancreatitis selected for resection procedures. Group 1 consisted of 31 patients with CP, group 2 consisted of 32 patients with PC. There was no coincidence of pancreatic cancer in CP group. The pancreatic tumor samples have been properly prepared in order to perform electrophoresis and immunoassay testing. The activity of MMPs and the concentrations of MMPs and TIMPs were evaluated. RESULTS: the revealed activities of gelatinases and concentrations levels of the gelatinases and their inhibitors were significantly higher in the PC tissue samples compared to CP. In both groups, higher concentrations of MMP9 compared to MMP2 and TIMP2 compared to TIMP1 were shown. High potential for tumor invasiveness demonstrated by the formation of lymph node metastases was characterized by the higher concentrations of MMP9 and TIMP2. However, in the case of infiltration of the nerve fibers, a decrease in the concentration of MMP2 was found. CONCLUSIONS: gelatinases and their inhibitors play important role in the pathogenesis of the CP as well as PC. The activity and concentration of gelatinases and the concentration of their inhibitors were all significantly higher in the PC group.

The influence of peripheral nerve graft's predegeneration stage on the regrowth of hippocampal injured neurites and concomitant changes in submicrosomal fraction proteins of grafts.

The present work has a twofold aim: 1. To ascertain whether the stimulative influence of peripheral nerve grafts on injured hippocampal neurons depends on the time lapse after transection and; 2. To examine whether the mentioned effect runs parallel to the time-dependent changes of proteins contents and composition in the submicrosomal fraction from transected rat sciatic nerves. Fluorescence microscope examination revealed that FITC-HRP labeled cells extending their neurites into the implanted peripheral nerve segments were particularly numerous among the hippocampal neurons when 7- and 35-day-old predegenegated distal stumps were used as grafts. Discontinuous SDS-slab polyacrylamide gel electrophoresis of submicrosomal fraction proteins obtained from distal stumps of rat sciatic nerves was performed at the 7, 14, 21 and 35 days after transection. Among the obtained protein fractions the most interesting seem to be the ones of 47 and 54 kDa, which reached maximal levels at the 7th day and the 50 kDa fraction with a maximum at the 35th experimental day. It is possible that the growth promoting power of the employed grafts depends on the presence of proper proteins.

Predegenerated peripheral nerve grafts rescue retinal ganglion cells from axotomy-induced death.

The inability of axons to grow across damaged central nervous system tissue is a well-known consequence of injury to the brain and spinal cord of adult mammals. Our previous studies showed that predegenerated peripheral nerve grafts facilitate neurite outgrowth from the injured hippocampus and that this effect was particularly distinct when 7-, 28-, and 35-day-predegenerated nerve grafts were used. The purpose of the present study was to use the above method to induce and support the regrowth of injured nerve fibers as well as the survival of retinal ganglion cells (RGCs). Adult Sprague-Dawley rats were assigned to three groups. In the experimental groups transected optic nerve was grafted with peripheral nerve (predegenerated for 7 days (PD) or nonpredegenerated). In the control group, the optic nerve was totally transected. RGCs and growing fibers labeled with fluorescent tracers were examined. They were counted and the results were subjected to statistical analysis. Retinal ganglion cells survived in the groups treated with predegenerated as well as nonpredegenerated grafts; however, the number of surviving retinal ganglion cells was significantly higher in the first one. In both groups the regrowth of the transected optic nerve was observed but the distance covered by regenerating fibers was longer in the PD group. No fibers inside grafts and no labeled cells in retinas were present in the control animals. On the basis of the obtained results we can state that the predegeneration of grafts enhance their neurotrophic influence upon the injured retinal ganglion cells.

Short-time predegenerated peripheral nerve grafts promote regrowth of injured hippocampal neurites.

Our previous studies revealed that predegenerated peripheral nerve grafts facilitated neurite outgrowth from the injured hippocampus and that this effect was particularly distinct when 7-, 28-, and 35-days predegenerated nerve grafts were used. It is recently known that a totally transected peripheral nerve exhibits biphasic neurite-promoting activity. The early phase lasts 7 days. The aim of the present study was to find whether short-time predegenerated (1-6 days) peripheral nerve grafts exert any neurotrophic effect and when this influence is maximal. Experiments were carried out on adult male Wistar rats. Sciatic nerves were totally transected and following 1, 2, 3, 4, 5 and 6 days their distal stumps were implanted into the hippocampus. Control animals were treated with non-predegenerated sciatic nerve grafts. In all groups FITC-HRP was injected into the free end of graft six weeks following surgery. Special histochemic technique showed AChE-positive fibres inside the grafts of all examined groups. Fluorescence microscopic examination revealed the labeled cells in all examined groups, however their number was different in each group, depending on the predegeneration stage. They were most numerous at the fourth day of predegeneration.

Purified extracts from short-time-predegenerated rats' sciatic nerves promote the regrowth of injured hippocampal neurites.

Our previous studies revealed that purified extracts (submicrosomal fractions) obtained from peripheral nerves predegenerated for 7-, 28-, and 35-days facilitated neurite outgrowth from the injured hippocampus. It is recently known that totally transected peripheral nerve exhibits biphasic neurite-promoting activity. The early phase lasts 7 days. The aim of the present study was to find whether extracts obtained from short-time predegenerated (1-6 days) peripheral nerves exert any neurotrophic effect and when this influence is maximal. Experiments were carried out on adult male Wistar rats. Sciatic nerves were totally transected and following 1, 2, 3, 4, 5 and 6 days their distal stumps were homogenized and centrifuged. Extracts were implanted into the hippocampus by means of autologous connective tissue chambers. Reference groups were treated with extracts from non-predegenerated nerves, NGF solution or fibrin (groups C, NGF and B + F, respectively). In all groups FITC-HRP was injected into the extracranial end of chamber six weeks following surgery. Histochemic technique showed AChE-positive fibres inside the chambers of all examined groups. Fluorescence microscopic examination revealed the labeled cells in all examined groups, however their number was different in each group. They were most numerous at the fourth day of predegeneration.

Autologous connective tissue chamber as a tool for introducing active substances into the CNS.

A new method of introducing active substances into the CNS is described. The autologous connective tissue chambers were obtained by implantation of a silicone tube under the back skin of rats. Subsequently they were filled with fibrine and additionally with NGF or submicrosomal fractions from nonpredegenerated and predegenerated peripheral nerves. Filled chambers were implanted stereotaxically into the injured hippocampus. The neurite outgrowth was examined by means of FITC-HRP and acetylcholinesterase-method. Implanted connective tissue chambers are very useful in getting active substances into the CNS. This method allows to avoid inflammatory processes and does not hinder the histological procedures.

Dead-ended autologous connective tissue chambers in peripheral nerve repair--early observations.

The effects of the repair of nerve gap injuries are still unsatisfactory, despite the great progress in microsurgery. Until now, there is no effective method to induce the regeneration of the transected peripheral nerve when its distal stump is missing. The aim of this work was to examine whether the implantation of dead-ended connective tissue chambers can promote the outgrowth of injured peripheral neurites. This method differs from all previous nerve guides because it totally eliminates the distal part of the nerve and restricts the influence of surrounding tissues. We have also tried to establish whether some neurotrophic factors can be applied by means of these chambers. The results of this work show that dead-ended autologous connective tissue chambers can be a useful tool in peripheral nerve injuries treatment, even when the distal part of the nerve is missing.