Biomedical subjects

Paweł Grieb

Publications and source records attributed to Paweł Grieb.

At least 19 recordsLinked to original sources

PubMed2006

Biventricular versus right ventricular pacing decreases immune activation and augments nitric oxide production in patients with chronic heart failure.

INTRODUCTION: Immune system activation and oxidative stress are involved in the pathogenesis of heart failure (HF). We aimed to test the hypothesis that upgrading from right ventricular pacing (RVp) to biventricular pacing (BiVp) can counteract these phenomena. METHODS: 28 HF patients, with BiVp were switched to RVp for one week, and then returned to BiVp. Immediately prior to, and 48 h after the return to BiVp, left ventricular (LV) systolic function was evaluated by echocardiography, and serum N-terminal pro-brain natriuretic peptide (NTproBNP), C-reactive protein (CRP), tumor necrosis factor alpha (TNF-alpha), interleukin 6 (IL6), nitric oxide metabolites (NO(x)) and malondialdehyde (MDA) were assayed. RESULTS: LV systolic function significantly improved 48 h after switching from RVp to BiVp: Ao-VTI (p<0.001), SV (p<0.001) and CO (p<0.001), and mitral regurgitation significantly decreased (p=0.003). At the same time, indices of peripheral immune activation decreased: TNF-alpha (p=0.02) and IL6 (p<0.001). MDA decreased (p<0.001), whereas NO(x) increased (p=0.04). NTproBNP and CRP did not change. In addition, in "responders" (i.e. CO increase >10% during BiVp vs. RVp) NTproBNP decreased and NO(x) increased. However, during BiVp, the decreases in TNF-alpha, IL6, and MDA occurred both in responders and in non-responders and were accompanied by a reduction in mitral regurgitation. CONCLUSION: The beneficial effect of BiVp compared to RVp extends beyond improving cardiac haemodynamics and comprises a decrease in immune activation accompanied by an increase in serum NO(x) and decrease in serum MDA.

Aged↗

PubMed2006

Maintenance of the rat transgenic model of familial amyotrophic lateral sclerosis expressing human SOD1G93A mutation.

A colony of transgenic rats expressing the human mutant Cu,Zn superoxide dismutase gene (hSOD1G93A) that is associated with some cases of familial form of amyotrophic lateral sclerosis (ALS) has been maintained in the Animal House of the Polish Academy of Sciences Medical Research Centre since 2003. This transgenic model, generated by Howland et al. (Proc Natl Acad Sci USA 2002; 99: 1604-1609), has been obtained under the material transfer agreement from Wyeth Corporation. The transgenic SOD1G93A (or 'Howland') rats develop neurological and neuropathological symptoms reminiscent of human ALS, i.e. progressive loss of motoneurons leading to paralysis and death. This paper describes maintenance of the transgenic rat colony, and general procedures used in experiments with these animals (i.e. genotyping, neurological observations, anaesthesia, etc.). At the beginning of the colony, up to the 3rd generation of the rats, symptoms of the model disease appeared at 95-125 days of age, and the animals survived till 120-145 days of age. Thereafter a gradual change in the disease phenotype occurred, and in the 8th generation approximately 1/3 of the rats displayed much slowed disease progression.

Amyotrophic Lateral Sclerosis↗

PubMed2006

Morphological changes and selective loss of motoneurons in the lumbar part of the spinal cord in a rat model of familial amyotrophic lateral sclerosis (fALS).

Morphological alterations and the course of changes in motoneuron counts were studied by light microscopy (cresyl violet staining) in the L2/L3 region of the spinal cord of hemizygotic transgenic rats carrying the amyotrophic lateral sclerosis-associated mutant human gene for Cu,Zn superoxide dismutase (hSOD1G93A) and of their non-transgenic littermates. In 60-day old transgenic rats, a few ischaemic-looking alpha-motoneurons and occasional vacuolization and accumulation of tigroid in some of the cells were apparent. On day 93 of life more distinct cellular pathology was found in transgenic rats, including moderate gliosis, neuronophagy of alpha-motoneurons, and occasional neuronophagy of gamma-motoneurons. In 120-day-old transgenic rats, abundant gliosis and profound neuronophagy of alpha-motoneurons were observed combined with occasional neuronophagy of other cells. Some loss of alpha-motoneurons was also apparent in 120-day-old non-transgenic littermates of the transgenic rats. No difference in alpha-motoneuron and gamma-motoneuron counts was found between the rats on day 60 of life (early presymptomatic stage of the model disease in the transgenic rats). At 93 days of age (late presymptomatic stage), alpha-motoneuron count, but not gamma-motoneuron count, tended to be lower (p=0.06) in the transgenic rats. On day 120 of life (symptomatic stage), alpha-motoneuron count in the transgenic rats was about half that in their nontransgenic littermates (p<0.001); at this time point the relative decline in alpha-motoneuron number in the former was 57% (day 120 versus day 60; p<0.001). A smaller decline in alpha-motoneuron count was also found in nontransgenic rats (day 120 vs day 60: 24%, p<0.05); this was not associated with the emergence of neurological symptoms or distinct changes in the cell morphology of the spinal cord region studied.

Amyotrophic Lateral Sclerosis↗

PubMed2006

Progression of morphological changes within CNS in a transgenic rat model of familial amyotrophic lateral sclerosis.

UNLABELLED: An analysis of the dynamics of histological and immunocytochemical changes in the CNS of a transgenic rat model of fALS in various periods of life was performed. Material was obtained from animals on the 60th day of age (4), 93rd day of age (3) and 120th presymptomatic day and from 3 animals in paretic stage of the disease. Formalin-fixed and paraffin-embedded slices were stained with HE and Klüver-Barrera method. Immunoreactions to GFAP, S-100, ferritin, neurofilament, ubiquitin, synaptophysin and tau protein were also performed. Within the brain tissues patchy neuronal loss and dark or ischaemic neurons were dispersed in cortical layers, CA1, CA3 and CA4 hippocampal areas and structures of the hemispheres and brain stem. In the spinal cord, numerous alpha motoneurons were dark or ischaemic. Vacuoles or small pale spots were visible in their cytoplasm. Microspongiosis surrounded some motoneurons, particularly cells subjected to neuronophagy. Neuronophagy, sporadically observed at the age of 60th day, was more extensive on the 93rd day of age, and at the age of 120 days already involved all interneurons of the anterior and posterior horns. In the immune reaction to neurofilament numerous fibres, often thick, fragmented or rosary-like, were observed. They were located within subcortical white matter, external and internal capsules, anterior horns of the spinal cord. Changes became more intensive with age. Astrocytic reactivity was weak in animals on the 60th and 93rd day of life. Non-numerous cells were immunoreactive to GFAP and S-100, although an increase of astrocytic nuclei was observed. On the 120th day of age and in symptomatic stage astrocytic hypertrophy and proliferation were intensive. But from the 60th day of age ubiquitin and tau protein immunopositive material was accumulated in the perinuclear area of astroglial cytoplasm. Immunoreaction of nerve cells to these proteins was negative. CONCLUSIONS: 1) In the subclinical stage of the disease the pathological process within the CNS takes place already on the 60th day of age and its intensity increases with age. 2) Morphological changes are not limited to motor neuronal cells. Various structures of the CNS are damaged. 3) Weak astroglial reaction probably depends on pathological accumulation of ubiquitin and tau protein in cytoplasm. 4) Astroglial cells are probably also a "target" for pathogenic factors in the rat model of fALS.

Age Factors↗

PubMed2006

Ultrastructural changes in lumbar spinal cord in transgenic SOD1G93A rats.

The purpose of this study was to determine structural changes which trigger the onset and progression of amyotrophic lateral sclerosis in rats expressing a human SOD1 transgene with mutation G93A. Lumbar spinal cord of affected rats in early and late presymptomatic (PM, 60 and 93 days of age) and symptomatic (S, 120 days of age) stage of the disease were analyzed ultrastructurally. At 60 days the structure of lumbar spinal cord as well as alpha motoneurons type S and F appeared normal; however, careful examination revealed that approximately 15% of axons were filled with mitochondria that were abnormal in number, size and morphology. Grossly swollen mitochondria with disrupted cristae were a prominent feature in all large axons at 93 days of age. At this time swelling and dilated mitochondria were observed also in type S motoneurons, while type F had small, well preserved mitochondria. At symptomatic stage the alpha motoneurons showed moderate neuronal loss, mainly of the S type. The most interesting finding at this stage was the occurrence of motoneurons with morphological signs of apoptotic-like degeneration. Such apoptotic-like motoneurons were characterized by nuclear and cytoplasmic condensation, chromatin compaction and formation of uniformly dense, dark structures. Numerous axons with very dark, compact interior as well as apoptotic bodies were irregularly scattered throughout the neuropil. Our ultrastructural study indicates that dying motoneurons in transgenic mutant SOD1G93A rats exhibit reminiscent apoptotic morphology which is preceded by significant mitochondrial abnormalities mainly in proximal axons and S motoneurons. Different reaction of slow and fast motoneurons to degenerating factors requires further analysis.

Animals↗

PubMed2005

Cytotoxic effects of cladribine and tezacitabine toward HL-60.

The aim of the study was to determine the relation between the cytotoxic and cytostatic effects of tezacitabine and cladribine on a HL-60 cell line and the time of exposure of cells to these drugs. Cell viability and induction of apoptosis were assessed using flow cytometry methods. Apoptosis was confirmed by direct microscopic observation. Growth inhibition was examined by cell counting. After 24 h incubation tezacitabine was equally or less toxic compared to cladribine. However, toxicity of tezacitabine strongly rose after 48 h incubation leading to massive cell death at doses much lower than those of cladribine. Assessment of the effect of increased exposure time on the clinical efficacy of tezacitabine is indicated.

Antineoplastic Agents↗

PubMed2004

Expansion of the Golgi apparatus in rat cerebral cortex following intracerebroventricular injections of streptozotocin.

Streptozotocin (STZ) is a bacterial toxin which selectively damages both insulin-producing cells and insulin receptors. Injections of STZ into the cerebral ventricles of experimental animals are followed by sustained biochemical, metabolic and behavioral effects resembling those which are found in human brains afflicted by Alzheimer's disease. The aim of the present study was to assess the effects of double intracerebroventricular application of STZ on the ultrastructure of rat frontoparietal cortical neurons. The most prominent change, seen 3 weeks after STZ injection, was a significant enlargement of the Golgi apparatus caused by expansion of the trans-Golgi segment of the cellular protein secretory pathway. Morphometric analysis revealed that the area of the trans part of the Golgi complex in neuronal cells was increased more than two-fold (median values: 312 x 10(3) nm in 14 neurons from control animals, and 846 x 10(3) nm3 in 19 neurons from STZ-treated animals, P = 0.0012), whereas that of the cis part did not significantly change. The effects of STZ did not resemble Golgi atrophy and fragmentation described in neurons from disease-prone brain structures of patients with Alzheimer's disease, but were similar to that observed after intravenous application of a non-metabolizable glucose analog 2-deoxyglucose. Considering that proamyloidogenic processing of beta-amyloid precursor protein may occur preferentially in the trans-Golgi segment, the observed early response of neuronal ultrastructure to desensitization of insulin receptors may predispose cells to form beta-amyloid deposits.

Animals↗

PubMed2004

[Impaired glucose tolerance and the risk of cardiovascular death].

Hyperglycemia and type 2 diabetes are an independent risk factor of cardiovascular (CV) disorders of atherosclerotic etiology. Proatherosclerotic sequelae of hyperglycemia comprise oxidative stress caused by increased production of free radicals, activation of leucocyte-endothelium interactions, and protein glycosylation. According to current reccomendations diabetes is diagnosed when plasma glucose concentration exceeds 10.0 mmol/L in 2-hour standard oral glucose tolerance test, whereas the result of 6.7-9.9 mmol/L speaks for asymptomatic impaired glucose tolerance (IGT) which does not require treatment. However, several data sets and their meta-analyses are suggestive of that not only diabetes, but also IGT is associated with significantly increased risk of cardiovascular death. A recent report indicated also that glycosylated hemoglobin HbA(1c) level is a continuous and very strong risk factor for CV death. In view of these data therapeutic interventions for IGT shall be considered.

Coronary Artery Disease↗

PubMed2004

Transgenic models of amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS), the most frequent paralytic disease of adults, is untreatable and invariably fatal. Up to 20% of ALS cases are inherited (familial, fALS) and associated with mutations, usually of the superoxide dismutase type 1 (SOD-1) gene. This paper shortly reviews the background for and the use of rodent transgenic models of ALS. Silencing the SOD-1 gene does not produce paralytic phenotype, but transgenic rodents expressing human mutated (hm) SOD-1 atop their own enzyme develop relatively selective and fatal degeneration of motoneurons. Many essential neuropathological and biochemical features of the paralytic disease in hmSOD-1 transgenic mice and rats are similar to human fALS, and these animals are currently considered a model of the human disease. Two types of hypotheses put forward to explain pathomechanism of motoneuron degeneration in hmSOD-1 transgenics (hence also in human ALS) are the "gain of function" hypotheses which assume that the mutated enzyme displays new toxic catalytic properties, and the "gain of interaction" hypotheses which assume that the mutated protein molecules are toxic because they became misfolded and undergo oligomerization. Transgenic animal models of ALS are used for preclinical assessments of new therapeutic approaches ranging from mono- and polipharmacotherapy to gene therapy and stem cell therapy.

Amyotrophic Lateral Sclerosis↗

PubMed2003

Effect of gamma-irradiation on cladribine and cladribine-containing biodegradable copolymers.

The aims of this study were to assess the effects of sterilization with gamma-irradiation on (i). bulk cladribine and (ii). cladribine-containing biodegradable copolymers. The stability of cladribine upon irradiation was confirmed by TLC, HPLC, UV, IR, DSC, rentgenography and electron microscopy. The stability of copolymers containing cladribine upon irradiation was assessed by IR, DSC and EPR. In vitro kinetics of nucleoside release from the copolymers before and after irradiation were compared, and only slight changes were found. Results of our study indicate that gamma-irradiation can be safely applied for the sterilization of cladribine or cladribine-containing copolymers for medical purposes.

Biodegradation, Environmental↗

PubMed2003

Oral citicoline treatment improves visual pathway function in glaucoma.

BACKGROUND: Increased latency and reduced amplitude of visual evoked potentials (VEP), frequently encountered in ocular hypertension or open-angle glaucoma, suggest slowed neural conduction in the visual pathways. An improvement in VEP latency and amplitude has been reported following repeated intramuscular injections of citicoline, a neuroprotective drug. Our aim was to find whether citicoline given orally would produce a similar effect. MATERIAL/METHODS: VEP latency and amplitude were measured in 21 glaucomatous eyes prior to and after two bi-weekly courses of citicoline taken orally in a dose of 1 gram/day. The treatment courses were separated by a two-week break; post-treatment VEP measurement was performed two weeks after the end of the second treatment. RESULTS: 62% of the eyes showed a response to the treatment, with VEP latency reduced from 123.5 (3.9 SEM) ms to 111.9 (1.9 SEM) ms (P=0.0008), and VEP amplitude increased from 6.56 (1.39 SEM) to 7.88 (1.16 SEM) (P=0.04). CONCLUSIONS: Citicoline given orally improves visual evoked potentials in some glaucoma patients.

Administration, Oral↗

PubMed2003

Preclinical development of biodegradable polymer foils for intracerebral delivery of cytotoxic nucleosides.

Intracerebral implantation of biodegradable polymers loaded with cytotoxic or radiosensitising nucleoside analogues is a promising treatment strategy for malignant gliomas, which are currently intractable. The aim of the study was to develop biodegradable polymers containing nucleosides which could be implanted intracerebrally. Methods of synthesis were developed for the copolymers composed of D,L-lactide, glycolide and caprolactone in different proportions, as well as a novel method of introducing nucleosides to these copolymers at the polymerisation step. Upon degradation in an aqueous medium some of these copolymers emit nucleosides in micromolar concentration over several months. Their in situ degradation and biocompatibility with brain tissues was assessed by means of scanning and transmission electron microscopy. At the ultrastructural level tissue responses to the copolymer implantation closely resembled the responses to mechanical trauma.

Animals↗

PubMed2002

5'-Esters of 2'-deoxyadenosine and 2-chloro-2'-deoxyadenosine with cell differentiation-provoking agents.

Phenylacetic and retinoic acids are carboxyacidic cell differentiating agents displaying anticancer activities. We report on a new class of compounds including the 5'-esters of 2'-deoxyadenosine (dA) or 2-chloro-2'-deoxyadenosine (cladribine, 2CdA) and the aforementioned acids. The rationale behind the synthesis of these esters was that if they are hydrolyzed inside the lymphoid cells, either dA will be removed from the intracellular environment by deamination, or 2CdA will be phosphorylated and accumulated. In either case targetted delivery of the differentiating agent to the lymphoid cells may be envisaged. The said compounds were synthesized by the Mitsunobu procedure employing triphenylphosphine and azadicarboxylic acid esters, and their stability was tested against various esterases. Esters of dA and 2CdA with phenylacetic acids were found to be resistant to enzymatic hydrolysis, whereas those with retinoic acids were efficiently hydrolyzed by commercially available hepatic esterase as well as by esterases present in the blood plasma and in diluted human lymphocyte lysate. Susceptibility to enzymatic hydrolysis was found to be a prerequisite of cytotoxic and/or differentiating activity of these esters in leukemic cell lines.

Antineoplastic Agents↗

PubMedDate not supplied

Citicoline treatment increases retinal dopamine content in rabbits.

Citicoline (exogenous cytidine-5'-diphosphocholine) was reported to enhance dopaminergic neurotransmission in the brain. A few clinical studies showed beneficial effects of this drug on the function of the visual pathway in patients with glaucoma or amblyopia. The present study was aimed at determining whether citicoline could influence retinal catecholamine levels in adult male Albino rabbits. The animals received the drug (50 mg/kg i.p., twice daily) or vehicle for 7 days, and retinal catecholamine concentrations were determined by HPLC. Compared to vehicle-treated controls, citicoline-treated animals displayed a significantly higher retinal dopamine concentration and a tendency toward an increase in adrenaline concentration, while the noradrenaline concentration remained unchanged. It is, therefore, conceivable that citicoline reinforces dopaminergic transmission in the retina.

Animals↗

PubMedDate not supplied

[A study of lyophylized human brain tumor tissue using MAS 1H-MRS spectroscopy].

AIMS: Proton magnetic spectroscopy of brain tumor extracts, and more recently magic angle spinning proton magnetic resonance spectroscopy (MAS 1H-MRS) of intact cooled tissue specimens have been used for tumor classification. The aim of this study was to obtain MAS 1H-MRS spectra of lyophilised and pulverised specimens of various brain tumors and to assess their utility for tumor type recognition. MATERIAL AND METHODS: Tissue samples of intracranial tumors were obtained at surgery and frozen immediately in liquid nitrogen. A part of each sample was subjected to a routine histopathological examination, while the rest was lyophilised, pulverised, and subjected to high-speed magic angle spinning MRS using Bruker DSX-400 WB AVANCE spectrometer and rotation speed up to 33 kHz. RESULTS: MAS 1H-MRS spectra of 39 samples (including 16 glioblastomas or gliosarcomas, 10 meningiomas and 5 craniopharyngiomas) were obtained. Invariably the spectra were dominated by broad lipid resonances, reflecting "NMR visible" protons in methyl,methylene and methine groups of fatty acid chains. Resolution of the spectra was markedly higher for glioblastomas/gliosarcomas and craniopharyngiomas than for meningiomas. CONCLUSIONS: Lyophylization of brain tumor specimens eliminates signals of watersoluble metabolites and results in a loss of discriminative power of the 1H-MRS analysis. Resolution of the spectra is increased for tumors that accumulate lipids extracellularly, but is not related to tumor histological grade.

Brain Neoplasms↗

PubMedDate not supplied

[Nucleoside analogs in the treatment of primary malignant brain tumors].

Standard therapeutic modalities including surgery, radio- and/or peripheral chemotherapy are ineffective in malignant gliomas. This is due to infiltration of distant brain areas by glioma cells and to the blood-brain barrier limiting penetration of anticancer drugs. One of the most promising experimental methods of glioma therapy is intracerebral implantation of biodegradable polymers containing cytotoxic compounds. This method allows to avoid peripheral toxicity of drugs. Considering that practically it is only malignant cells that proliferate in the brain, the use of drugs displaying selective toxicity toward DNA-replicating cells might help to avoid central toxicity as well. Several nucleoside analogs display selective cytotoxic and/or radiosensitizing effects on proliferating cells. Despite encouraging results obtained in the in vitro and animal models of gliomas, peripheral administration of these drugs turned out to be ineffective in the clinical settings. Intracerebral implantation of nucleoside analogs-containing biodegradable polymers may be much more efficacious, especially when combined with radiotherapy. Appropriate nucleoside analogs may also be employed in cell-selective radiotherapy and gene therapy of malignant gliomas.

Antineoplastic Agents↗

PubMedDate not supplied

[5-Aminolevulinic acid (ALA) and its applications in neurosurgery].

Delta-aminolevulinic acid (ALA) is a precursor of the synthesis of porphyrins including heme produced in all mammalian cells. Exogenous ALA induces selective accumulation of the other heme precursor, protoporphyrin IX (PpIX), in neoplastic cells, such as those of malignant gliomas. Upon exposure to violet-blue light PpIX becomes activated, which results in red-light fluorescence as well, as in photodynamic oxidations which may be lethal to the cells. In neurosurgery ALA is used for intraoperative labeling of the border regions of malignant gliomas infiltrated by alive clonogenic tumor cells (ALA-PDD), and is helpful in precise resection of these regions. Clinical data indicate that ALA-PDD-assisted resection of malignant gliomas may result in statistically significant prolongation of postoperative survival. Ongoing research concentrates also on the use of ALA for a selective elimination of glioma cells in situ, and on lipophilic ALA derivatives with more favorable pharmacokinetic properties.

Aminolevulinic Acid↗

PubMedDate not supplied

Tezacitabine blocks tumor cells in G1 and S phases of the cell cycle and induces apoptotic cell death.

Tezacitabine (FMdC) is a new cytostatic/cytotoxic agent widely investigated in clinical trials and on the cellular level. In a previous paper (3) we worked on human and murine leukemia (L-1210, HL-60, and MOLT-4) cells, and in this paper we investigated the influence of FMdC on the cell cycle and apoptosis in vitro of three other leukemias (CCRF-SB, KG-1, and Jurkat), and human solid tumor (carcinoma) cell lines (COLO-205, MCF-7, and PC-3). We found that FMdC induces the G1 (at concentrations higher than 10 nM). and S-phase (at low concentration) leaky block of the cell cycle. FMdC also effectively induces apoptotic death of cells by the caspase 3/7 pathway. We found also that FMdC induces intensive changes in the protein metabolism. These changes are correlated with the cell death.

Animals↗