Paweł Grieb

2-Chlorodeoxyadenosine (2-CdA) in 2-Hour Versus 24-Hour Intravenous Infusion in the Treatment of Patients with Hairy Cell Leukemia

Forty one patients with hairy cell leukemia (HCL) were treated with 2-chloro-deoxyadenosine (2-CdA) administered in various schedules. Complete remission (CR) was achieved in 31 (76%) patients and partial remission (PR) in 9 (22%). The mean duration of remission (CR + PR) was 25.2 months (range 9-45 months). One patient did not respond to therapy. Twelve out of 16 patients (75%) achieved CR after 5-day intravenous infusions of 2-CdA and 19 out of 25 patients (76%) after 7-day courses. In 19 out of 23 patients (82.6%) CR was achieved after intermittent 2-hour infusions and in 12 out of 18 (66.7%) after continuous 24-hour infusion. The differences were not statistically significant. Side effects of 2-CdA were similar in both groups except for infections, which were less frequently observed in the group treated for 5 days. The results of our study suggest that 2-CdA can be effectively administered to patients with HCL using 5-day courses and a 2-hour daily infusion.

Decreased level of kynurenic acid in cerebrospinal fluid of relapsing-onset multiple sclerosis patients

The present study was undertaken to measure cerebrospinal fluid (CSF) levels of kynurenic acid (KYNA) in patients with relapsing-onset multiple sclerosis (MS) during remission or not progressing for at least 2 months. In these patients the levels of CSF KYNA were found to be significantly lower compared with subjects with non-inflammatory neurological diseases, as well as those with inflammatory disease (median (interquartile range): 0.41 (0.3-0.5) pmol/ml, n=26 vs. 0.67 (0.5-1.1), n=23, P<0.01 and 1.7 (1.5-2.6), n=16, P<0.001, respectively). These results provide further evidence of the alterations in the kynurenine pathway during remitting-onset MS.

Metabolic Changes in Rat Brain Following Intracerebroventricular Injections of Streptozotocin: A Model of Sporadic Alzheimer’s Disease

A decrease in cerebral glucose metabolic uptake is an early and characteristic sign of Alzheimers disease (AD). Streptozotocin (STZ) is a bacterial toxin which damages insulin-producing cells and insulin receptors. Intracerebroventricular (icv) application of STZ in rats has been found to chronically decrease cerebral glucose uptake and produce other effects that bear a resemblance to several other molecular and pathological features of AD. In the present experiments in vivo (1)H MR Spectroscopy with short echo time (3 ms) was used to non-invasively obtain a neurochemical profile of rat brains, 3 weeks and 2 months after double icv injections of STZ or vehicle. Seventeen metabolites were quantified from 27 microL tissue volume which included hippocampus and a part of cerebral cortex, using the LCModel and unsuppressed water signal as an internal reference. Three weeks after icv STZ several metabolites were significantly decreased, the most prominent changes noted in glycerophosphocholine and phosphocholine (-38 +/- 5%), glutathione (-37 +/- 4%), taurine (-30 +/- 19%), glutamate (-26 +/- 14%), phosphocreatine (-23 +/- 15%) and N-acetylaspartate (-16 +/- 6%). On the contrary, the concentration of N-acetylaspartylglutamate was found significantly increased (+38 +/- 18%). After 2 months some of these changes were even more pronounced. We conclude that in vivo (1)H MRS of rat brain following icv STZ injections provides a new input into a better understanding of the critical dependency of neural function and structure on brain glucose consumption, and may be of relevance in further studies of AD pathomechanism.

Intracerebroventricular Streptozotocin Injections as a Model of Alzheimer’s Disease: in Search of a Relevant Mechanism

Streptozotocin (STZ), a glucosamine-nitrosourea compound derived from soil bacteria and originally developed as an anticancer agent, in 1963 has been found to induce diabetes in experimental animals. Since then, systemic application of STZ became the most frequently studied experimental model of insulin-dependent (type 1) diabetes. The compound is selectively toxic toward insulin-producing pancreatic beta cells, which is explained as the result of its cellular uptake by the low-affinity glucose transporter 2 (GLUT2) protein located in their cell membranes. STZ cytotoxicity is mainly due to DNA alkylation which results in cellular necrosis. Besides pancreatic beta cells, STZ applied systemically damages also other organs expressing GLUT2, such as kidney and liver, whereas brain is not affected directly because blood-brain barrier lacks this transporter protein. However, single or double intracerebroventricular (icv) STZ injection(s) chronically decrease cerebral glucose uptake and produce multiple other effects that resemble molecular, pathological, and behavioral features of Alzheimer’s disease (AD). Taking into consideration that glucose hypometabolism is an early and persistent sign of AD and that Alzheimer’s brains present features of impaired insulin signaling, icv STZ injections are exploited by some investigators as a non-transgenic model of this disease and used for preclinical testing of pharmacological therapies for AD. While it has been assumed that icv STZ produces cerebral glucose hypometabolism and other effects directly through desensitizing brain insulin receptors, the evidence for such mechanism is poor. On the other hand, early data on insulin immunoreactivity showed intense insulin expression in the rodent brain, and the possibility of local production of insulin in the mammalian brain has never been conclusively excluded. Also, there are GLUT2-expressing cells in the brain, in particular in the circumventricular organs and hypothalamus; some of these cells may be involved in glucose sensing. Thus, icv STZ may damage brain glucose insulin producing cells and/or brain glucose sensors. Mechanistic explanation of the mode of action of icv STZ, which is currently lacking, would provide a valuable contribution to the field of animal models of Alzheimer’s disease.

The application of microspheres from the copolymers of lactide and ϵ-caprolactone to the controlled release of steroids

Abstract The microspheres made of the copolymers of lactide and ϵ-caprolactone were used for the controlled release of progesterone and β-estradiol. The copolymers contained 83–94% of l or d,l -lactide. The influence of the microstructure of lactidyl blocks in the copolymer chains on the drug release rate was studied. More uniform release rate was observed in the case of the copolymer derived from d,l -lactide as composed to l -lactide. For the copolymer containing 83–94% of d,l -lactide units the progesterone and β-estradiol release rate in vitro was found to be practically constant within over 40 days. The in vivo studies performed on rats revealed that the period of constant release rate of β-estradiol can be prolonged to about 70 days. The microspheres made of the applied poly-( d,l -lactide-co-ϵ-caprolactone) are the convenient system for long time release of steroids.

Role of short TE 1H-MR spectroscopy in monitoring of post-operation irradiated patients

Post-surgical radiation therapy is a routine procedure in the treatment of primary malignant brain tumors. Along with modest therapeutic effects conventional fractionated radiotherapy, in spite of any modifications, produces damage to non-malignant brain tissues lying within the treatment volume, the extent of which depends on radiation dose. Serial 1H-MRS allows non-invasive investigation of tissue metabolic profiles. In the present study the ratios of resonance signals assigned to the major 1H-MRS-visible metabolites (N-acetylaspartate, choline, creatine, inositol, lactate and lipid methylene group) were evaluated before, during and after post-surgical fractionated radiotherapy in brain regions close to and more distant from the tumor bed, receiving different radiation exposures (60 and < 40 Gy, respectively). The study group consisted of ten patients (aged 28-51). A MRI/MRS system (Elscint 2T Prestige) operating at the field strength of 2 T and the proton resonance frequency of 81.3 MHz has been used and the 1H-MR spectra were acquired using single voxel double-spin-echo PRESS sequence with a short TE. The spectra were post-processed with automatic fitting in the frequency domain. It was found that although the metabolite profiles depend on the dose obtained, but other stress factors (like surgery) seem to contribute to the overall picture of the metabolic status of the brain as well. In studies of early irradiation injuries, an increase of choline related ratios may serve rather as cell proliferation indictors than as cell injury ones, whereas the mI/Cr ratio appears as one of the first indicators of local irradiation injury. In order to establish the prognostic marker for early radiation damage, however, it seems necessary to analyze all visible metabolites as well. None of the metabolites separately may serve as such an indicator due to the complexity of tissue metabolism. Interestingly, MRI reveals no changes during the therapy process, whereas the metabolite ratios are being affected in the course of time, thus supporting the presumption that the 1H-MRS is a valuable method of radiation therapy monitoring.

Pharmacodynamics of citicoline relevant to the treatment of glaucoma.

Citicoline (exogenous CDP‐choline) is a nontoxic and well‐tolerated drug used in pharmacotherapy of brain insufficiency and some other neurological disorders, such as stroke, brain trauma, and Parkinsons disease. A few reports indicate that citicoline treatment may also be beneficial in glaucoma. Currently glaucoma is considered a neurodegenerative disease in which retinal ganglion cells (RGC) slowly die, likely in the apoptotic mechanism. Endogenous CDP‐choline is a natural precursor of cellular synthesis of phospholipids, mainly phosphatydylcholine (PtdCho). Enhancement of PtdCho synthesis may counteract neuronal apoptosis and provide neuroprotection. Citicoline, when administered, undergoes a quick transformation to cytidine and choline, which are believed to enter brain cells separately and provide neuroprotection by enhancing PtdCho synthesis; similar effect may be expected to occur in glaucomatous RGC. Furthermore, citicoline stimulates some brain neurotransmitter systems, including the dopaminergic system, and dopamine is known as a major neurotransmitter in retina and postretinal visual pathways. In a double‐blind, placebo‐controlled study, treatment of glaucoma resulted in functional improvement in the visual system noted with electrophysiological methods. Development of citicoline as a treatment for glaucoma is indicated.

Neuroprotective Properties of Citicoline: Facts, Doubts and Unresolved Issues

Citicoline is the generic name of the pharmaceutical substance that chemically is cytidine-5′-diphosphocholine (CDP-choline), which is identical to the natural intracellular precursor of phospholipid phosphatidylcholine. Following injection or ingestion, citicoline is believed to undergo quick hydrolysis and dephosphorylation to yield cytidine and choline, which then enter the brain separately and are used to resynthesize CDP-choline inside brain cells. Neuroprotective activity of citicoline has been repeatedly shown in preclinical models of brain ischaemia and trauma, but two recent, large, pivotal clinical trials have revealed no benefits in ischaemic stroke and traumatic brain injury. However, the substance seems to be beneficial in some slowly advancing neurodegenerative disorders such as glaucoma and mild vascular cognitive impairment. This paper critically discusses issues related to the clinical pharmacology of citicoline, including its pharmacokinetics/biotransformation and pharmacodynamics/mode of action. It is concluded that at present, there is no adequate description of the mechanism(s) of the pharmacological actions of this substance. The possibility should be considered and tested that, in spite of apparently fast catabolism, the intact citicoline molecule or the phosphorylated intermediate products of its hydrolysis, cytidine monophosphate and phosphocholine, are pharmacologically active.

Astrocytic activation in relation to inflammatory markers during clinical exacerbation of relapsing-remitting multiple sclerosis

SummaryThe study aimed to assay the cerebrospinal fluid (CSF) levels of protein S100B, a biomarker of astrocyte activation in relation to kynurenic acid (KYNA) and nitric oxide (NO) metabolites, nitrate/nitrite (NOx) concentrations in acute relapse multiple sclerosis (MS) patients. Twenty relapsing-remitting MS (RR-MS) patients and 10 controls were enrolled. RR-MS patients were assessed on the expanded disability status scale (EDSS) and underwent lumbar puncture. The CSF KYNA, NOx and S100B levels were significantly higher in RR-MS group compared to controls (p = 0.01, 0.001, 0.04, respectively). There was a significant correlation between CSF S100B and KYNA (p = 0.01) but not NOx (p > 0.05) in RR-MS. CSF KYNA, NOx or S100B concentrations did not correlate with disease characteristics of MS patients.Our study suggests the activation of the kynurenine pathway leading to the increase of neuroprotective KYNA in the CSF of MS patients during acute relapse what contrasts with chronic phases of the disease.

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.