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Biomedical subjects

R Stach

Publications and source records attributed to R Stach.

At least 19 recordsLinked to original sources
PubMed2000

[Cytotoxicity study of high gold content Degutan surfaces of various degrees of roughness with fibroblasts (BALB 3T3) and osteoblasts (hFOB 1.19)].

The cytotoxicity of Degutan surfaces with different degrees of roughness, and the effect of surface structures on osteoblast proliferation and differentiation, was investigated with standardised cell culture systems. Fibroblast cell lines (BALB/3T3) and osteoblast cell lines (hFOB 1.19) were used. The number and variability of the cells were determined for assessment of proliferation and alkaline phosphatase activity, collagen I and osteocalcin production were used as parameters for differentiation. In the early phase, the largest numbers of cells and greatest proliferation were measured on polished Degutan surfaces. In the late phase, however, larger numbers of cells and a greater degree of proliferation were to be seen on sandblasted and sandblasted/heat-treated Degutan surfaces. No differences were found for collagen I, osteocalcin production or alkaline phosphatase activity. Neither the osteoblasts nor the fibroblasts revealed a toxic effect of Degutan. The results for osteoblast differentiation correlate with recent studies on identical structured titanium surfaces. In view of the immeasurable amount of ion release, Degutan may be considered an ideal model for an inert material surface.

3T3 Cells↗
PubMed1999

Electromagnetic fields influence NGF activity and levels following sciatic nerve transection.

Pulsed electromagnetic fields (PEMF) have been shown to increase the rate of nerve regeneration. Transient post-transection loss of target-derived nerve growth factor (NGF) is one mechanism proposed to signal induction of early nerve regenerative events. We tested the hypothesis that PEMF alter levels of NGF activity and protein in injured nerve and/or dorsal root ganglia (DRG) during the first stages of regeneration (6-72 hr). Rats with a transection injury to the midthigh portion of the sciatic nerve on one side were exposed to PEMF or sham control PEMF for 4 hr/day for different time periods. NGF-like activity was determined in DRG, in 5-mm nerve segments proximal and distal to the transection site and in a corresponding 5-mm segment of the contralateral nonoperated nerve. NGF-like activity of coded tissue samples was measured in a blinded fashion using the chick DRG sensory neuron bioassay. Overall, PEMF caused a significant decrease in NGF-like activity in nerve tissue (P < 0.02, repeated measures analysis of variance, ANOVA) with decreases evident in proximal, distal, and contralateral nonoperated nerve. Unexpectedly, transection was also found to cause a significant (P=0.001) 2-fold increase in DRG NGF-like activity between 6 and 24 hr postinjury in contralateral but not ipsilateral DRG. PEMF also reduced NGF-like activity in DRG, although this decrease did not reach statistical significance. Assessment of the same nerve and DRG samples using ELISA and NGF-specific antibodies confirmed an overall significant (P < 0.001) decrease in NGF levels in PEMF-treated nerve tissue, while no decrease was detected in DRG or in nerve samples harvested from PEMF-treated uninjured rats. These findings demonstrate that PEMF can affect growth factor activity and levels, and raise the possibility that PEMF might promote nerve regeneration by amplifying the early postinjury decline in NGF activity.

Animals↗
PubMed1998

Evidence for and implications of SV40-like sequences in human mesotheliomas and osteosarcomas.

Pleural mesotheliomas and osteosarcomas develop in hamsters injected intracardially with SV40. Using primers specific for the RB-pocket binding domain of SV40 we analysed with the polymerase chain reaction frozen specimens from 48 human mesotheliomas and 145 human bone tumours. We found that 60% of human mesotheliomas and 33% of human bone tumours contained SV40-like DNA. Immunostaining, Western blot and RNA in situ hybridization experiments revealed SV40 Tag expression in human mesotheliomas. Osteosarcomas were not studied for Tag expression because not enough material was available. Finally, antibodies anti-Tag were detected in the sera collected from patients with mesothelioma. These data indicate that SV40, or a closely related virus, is/are present in human mesothelioma and osteosarcoma.

Animals↗
PubMed1998

Simian virus 40 oncogenesis in hamsters.

Simian virus 40 (SV40) is a DNA tumour virus which is highly oncogenic in hamsters. Only specific histologic types of tumours develop in hamsters injected with SV40, and these are influenced by the route of virus inoculation. When SV40 is injected systemically to expose most different cell types to the virus, the animals develop mesotheliomas, osteosarcomas, sarcomas, and lymphomas within six months. When the virus is injected subcutaneously, sarcomas at the site of injection develop. If hamsters are injected intracranially with SV40, they develop ependymomas. These same tumour types have been found to contain SV40.

Animals↗
PubMed1983

Opioid peptides, particularly dynorphin, after amygdaloid-kindled seizures.

The influence of amygdaloid kindling on brain and pituitary content of immunoreactive dynorphin (IR-DYN) and other opioid peptides was studied in rabbits. The kindling was very effective in increasing the hippocampal levels of IR-DYN, alpha-neoendorphin and Leu-enkephalin, but remained without any significant effect on the levels of IR-DYN and beta-endorphin in the majority of brain structures studied. The concentration of IR-DYN in the hippocampus remained at the control level throughout the development but was increased dramatically after completion of kindling. Biochemical alterations persisted for at least one month following the completion of kindling. The obtained results suggest that the hippocampal IR-DYN and related peptides may play some role in the maintenance of amygdaloid-kindled seizures.

Amygdala↗
PubMed1983

Influence of clonazepam on thalamocortical phenomena in rats.

The influence of clonazepam on thalamo-cortical phenomena was studied in acute experiments in 20 rats. Early components of cortical responses to electrical stimulation of either LA or VDM thalamic nuclei remained unchanged. Only the latency of the late N2 component was significantly shortened after CZP. CZP did not change the incidence of rhythmic after-discharge ("thalamo-cortical spindles") and tended to prolong them. Two types of self-sustained after-discharges of an epileptic nature which could appear after the end of rhythmic thalamic stimulation were influenced differently: Spike-and-wave type was invariably suppressed, serrated wave type of SSAD was generally unchanged by CZP. This last finding speaks in favour of the hypothesis that these two types of SSADs could serve as models of two different epileptic seizures.

Animals↗
PubMed1983

[Evaluation of health hazards of workers of the textile industry working in contact with latex substances on the acrylic compound base].

The paper is aimed at quantitative and qualitative determination of acrylic compounds that may occur in air at the "Lentex" Plant in Lubliniec, along with microclimate parameters measurements. The initial method was that of the Polish Standard PN-78/z-04113, which was subsequently modified. Pursuant to this standard, acrylic compounds were determined by gas chromatography with new column pack and changed parameters of gas chromatograph. The conditions of acrylic esters and acrylonitrile separation on column with LAC-1R-296 phase were considered the best and were used for quantitative and qualitative estimation. The investigations were carried out at workstations, basing on the production stage. The obtained results of identified acrylates concentrations are indicative of a very little content of those compounds in workstations air, implying that those workstations are safe in respect of chemical risk to workers. Certain deviations from mandatory standards were exhibited by almost all microclimatic parameters which might result in workers' worse general feeling.

Acrylates↗
PubMed1981

Serotonergic mechanism in seizures kindled from the rabbit amygdala.

The effect of agents enhancing or diminishing serotonergic activity on seizures kindled from the rabbit amygdala was examined. Acute administration of 5-hydroxytryptophan (5-HTP) 10 and 25 mg/kg (administered in combination with a peripheral decarboxylase inhibitor), quipazine 1, 5 and 10 mg/kg or femoxetine 5 and 15 mg/kg which enhance serotonergic activity affected neither the intensity of behavioral seizures nor the duration of bioelectrical ones. 5-HTP 25 mg/kg and femoxetine 15 mg/kg prolonged the duration of behavioral seizures. Chronic administration of 5-HTP 25 mg/kg and femoxetine 15 mg/kg prolonged the duration of behavioral seizures. Chronic administration of 5-HTP 25 mg/kg had no effect on the development of kindled seizures. Acute administration of p-chlorphenylalanine (PCPA) 250 mg/kg reduced the intensity and shortened the duration of behavioral seizures. Cyproheptadine which blocks the postsynaptic action of serotonin shortened the duration of behavioral seizures. Chronic administration of PCPA 80 mg/kg delayed the development of kindled seizures. It is concluded that a pharmacological stimulation of the serotonergic system exerts no or little enhancing effect, whereas pharmacological inhibition of this system attenuates and delays the development of seizures kindled from the rabbit amygdala.

5-Hydroxytryptophan↗
PubMed1981

Effect of chronic para-chlorophenylalanine treatment on convulsive-seizure reactions.

The effect of chronic para-chlorphenylalanine (PCPA) treatment was investigated in two different seizure models: the pentylenetetrazole (PTX) seizure model in rats and the kindled seizures from rabbit amygdala. Chronic PCPA treatment (21 days) in male albino rats caused a progressive decrease in the 5-hydroxytryptamine (5-HT) brain level between the 1st and the 7th day of PCPA administration. Then the 5-HT level remained low until the end of the experiment. On the background of the low 5-HT level there occurred changes in PTZ convulsive reactions: after the 3rd day of PCPA treatment the convulsive-seizure reactivity was significantly increased and after the 7th, 14th and 21st day the increased seizure reactivity performed only as a tendency, though the 5-HT level was still low. Chronic PCPA treatment (16 days) of rabbits delayed the development of the behavioural kindled seizures. This treatment also reduced the duration of bioelectrical seizures until the 8th day of treatment, especially in the motor cortex. The observed different effect of the chronic PCPA treatment in both seizure models: pentylenetetrazole in rats and kindling in rabbits might be explained by essential differences in the origin and mechanisms of development of the two seizure models.

Amygdala↗
PubMed1977

Effect of combined dopaminergic and GABA-ergic stimulation on ouabain-induced epileptiform activity.

In this study we tested a hypothesis that dopamine and GABA receptor-stimulating agents given together might mutually potentiate their anticonvulsant activities. To test this hypothesis, experiments were performed on free-moving rabbits with epileptiform activity evoked by cortical application of ouabain. After combined treatment with apomorphine and GHBA 3 out of 6 animals displayed no EEG epileptiform activity, and in the remaining 3 rabbits this activity was greatly reduced. A combined pretreatment with apomorphine and GHBA abolished epileptiform EEG activity during the first hour and shortened it during the second hour, but not significantly. Apomorphine given together with amino-oxyacetic acid before ouabain completely abolished the epileptiform activity in 4 out of 6 animals. In the remaining 2 rabbits the latency of ouabain affect was prolonged, the epileptiform activity during the first hour was abolished, and it was markedly decreased during the next 2 hr (significantly from controls or groups receiving apomorphine or amino-oxyacetic acid). Phenytoin was less potent than apomorphine with GHBA or apomorphine given together with AOAA. The animals' behavior was observed.

Aminooxyacetic Acid↗
PubMed1976

The influence of neuromediators injected into nucleus caudatus on bioelectrical seizure activity of amygdala.

The influence of electrical and chemical stimulation of nucleus caudatus (NC) on bioelectrical seizure activity of amygdala (Am) was studied in rabbits. The electrical stimulation of NC inhibits seizures in Am induced by the administration of picrotoxin into this nucleus. Dopamine (DA) and cholinomimetics-metacholine and neostygmine-applied into NC inhibit seizures in Am. Noradrenaline (NA) acts biphasically, first potentiating and then inhibiting seizures in Am. Serotonin (5-HT) and glutamic acid (GA) administered to NC do not affect the seizures. In the case of seizures excited by electrical stimulation, DA and neostygmine possessed inhibiting action; NA, too, inhibited seizures without, however, inducing primary stimulation. Similarly as in the case of picrotoxin-stimulated seizures, neither 5-HT nor GA brought about the effects. The present study deals with the correlation of dopaminergic anc cholinergic systems in NC.

Amygdala↗