Sequence-specific DNA strand cleavage by <Superscript>111</Superscript>In-labeled peptide nucleic acids

Peptide nucleic acids (PNAs) bind tightly and sequence-specifically to single- and double-stranded nucleic acids, and are hence of interest in the design of gene-targeted radiotherapeutics that could deliver the radiodamage to designated DNA and/or RNA sites. As a first step towards this goal, we developed a procedure for incorporation of Auger electron-emitting radionuclide (indium-111) into PNA oligomers and studied the efficiency of PNA-directed cleavage of single-stranded DNA targets. Accordingly, diethylene triamine penta-acetic acid (DTPA) was conjugated to the lysine-appended mixed-base PNAs and sequence-homologous DNA oligomer with a proper linker for comparative studies. By chelation of PNA-DTPA and DNA-DTPA conjugates with ¹¹¹In³⁺ in acidic aqueous solutions, ¹¹¹In-labeled PNA and DNA oligomers were obtained. Targeting of single-stranded DNA with PNA-DTPA-[¹¹¹In] conjugates yielded highly localized DNA strand cleavage; the distribution of breaks along the target DNA strand has two maxima corresponding to both termini of PNA oligomer. After 10–14 days, the overall yield of breaks thus generated within the PNA-targeted DNA by ¹¹¹In decay was 5–7% versus 2% in the case of control oligonucleotide DNA-DTPA-[¹¹¹In]. The estimated yield of DNA strand breaks per nuclear decay is ~0.1 for the PNA-directed delivery of ¹¹¹In, which is three times more than for the DNA-directed delivery of this radionuclide. This in vitro study shows that ¹¹¹In-labeled PNAs are much more effective than radiolabeled DNA oligonucleotides for site-specific damaging of DNA targets. Accordingly, we believe that PNA oligomers are promising radionuclide delivery tools for future antisense/antigene radiotherapy trials.     

An integrative psychophysiological approach to brain hemisphere functions in schizophrenia

The present paper proposes a new psychophysiological approach to the genesis of positive and negative schizophrenic symptoms. According to this approach, the initial factor in schizophrenic disorders is a functional insufficiency of the right hemisphere which can be determined by early emotional experience in combination with subtle brain damage. This functional insufficiency causes (a) the inability to grasp and select information before its realization; and (b) the inability to produce a polysemantic context which is crucial for creativity, psychological defense, and the restoration of search activity, all of which determine psychophysiological adaptation to the environment. Right hemisphere insufficiency causes left hemisphere hyperactivity as an ineffective attempt to compensate for this functional deficiency. As a result, normal search activity is replaced by artificial search activity which is represented by “positive” symptoms, and which uses the predisposition of the left hemisphere's catecholamine system for its increased activity. The suggestion is made that cognitive impairment in schizophrenia (the inability to use appropriate previous information in relation to current perceptual input) is related to the competition between information processing which requires left hemisphere activity, and the formation of positive symptoms, also based on left hemisphere activity.     

Modulation of electroencephalographic responses to transcranial magnetic stimulation: evidence for changes in cortical excitability related to movement

Transcranial magnetic stimulation (TMS) and multichannel electroencephalography (EEG) were used for the investigation of cortical excitability preceding voluntary movement in human subjects. The study showed the practical value of the combined TMS-EEG approach in differentiating between cortical and spinal-cord mechanisms, which is difficult with conventional electromyographic measures alone. TMS induced a pronounced negativity (N100) lasting for 150-200 ms, with the amplitude maximum in the stimulated hemisphere. When TMS was applied just before the onset of the visually triggered movement, N100 was markedly attenuated, although motor evoked potentials (MEPs) became larger. We suggest that the N100 component represents an inhibitory response following TMS. This interpretation is in agreement with intracellular recordings in animals, paired-pulse TMS studies and experiments showing increased premovement excitability on the basis of MEPs. N100 was not affected only by the subsequent movement, but also by the switching from rest to the motor-task condition, which caused a slight attenuation of the N100 component; no changes, however, were found in the amplitude of MEPs, suggesting that modified excitability did not affect the output of the corticospinal pyramidal cells. By contrast to MEPs, N100 was modulated also by the presentation of the visual stimulus alone, i.e. when no movement was required. This attenuation suggests that even in a rest condition visual stimuli have an access to the sensorimotor regions of the cortex, most probably through ascending arousal brain systems.     

Dynamics of corrected QT interval and heart rate in patients with early postinfarction angina

The subjects of the study were 135 patients with acute Q-wave and non-Q-wave myocardial infarction (MI) aged 36 to 78 years (mean 62.4 +/- 11.2 years). 59 patients (main group) developed early postinfarction angina (EPA). 76 patients (control group) had no stenocardia attacks within the entire period of hospital treatment. In the patients with EPA corrected QT interval dispersion was greater within the entire period of hospital treatment: 81.2 +/- 7.6 and 67.1 +/- 4.6 ms1/2 on the first day, 74.6 +/- 6.0 and 70.3 +/- 4.7 ms1/2 on the third day, 82.1 +/- 6.5 and 71.6 +/- 6.2 ms1/2 on the seventh day, 88.7 +/- 6.2 and 69.4 +/- 8.2 ms1/2 on the 28th day, respectively. Heart rate entropy decreased in both groups, but before discharge (mean 28th day) the patients with EPA demonstrated its significant reduction compared to the patients without EPA (3.89 +/- 0.16 and 4.13 +/- 0.09 bits, respectively, p < 0.05). Thus, recurrent myocardial ischemia in patients with MI, manifesting by EPA attacks, leads to the increase of QT interval dispersion and to heart rate rigidity which apparently mirrors greater probability of myocardial electric instability and increased risk of fatal arrhythmias in such patients.     

Ligand-exchange chromatography of racemates, 9. Ligand-exchange chromatography of amino acid enantiomers on asymmetric sorbents with polydentate sulfur containing groupings

The paper describes the syntheses of four asymmetric sorbents, which contain S-(2-aminoethyl)-L -cysteine ( 1a ), S-(carboxymethyl)-L -cysteine ( 1c ), S,S′-(ethylene)-bis(L -cysteine) ( 2a ), and N,N′-(ethylene)-bis(D-methionine) ( 3a ) groupings as the chiral fixed ligands in a cross-linked polystyrene matrix. The sorbents were used for ligand-exchange chromatography of amino acid enantiomers in the presence of Cu(II) and Ni(II) ions. Enantioselective effects in the formation of mixed-ligand complexes consisting of a fixed ligand, a metal ion, and an amino acid enantiomer were determined. The highest values of enantioselectivity reaching 1 300 to 1 890J/mol were found in mixed-ligand complexes containing histidine or β-phenyl-α-alanine.     

Variability in apoptotic response to poliovirus infection

In several cell types, poliovirus activates the apoptotic program, implementation of which is suppressed by viral antiapoptotic functions. In such cells, productive infection leads to a necrotic cytopathic effect (CPE), while abortive reproduction, associated with inadequate viral antiapoptotic functions, results in apoptosis. Here, we describe two other types of cell response to poliovirus infection. Murine L20B cells expressing human poliovirus receptor responded to the infection by both CPE and apoptosis concurrently. Interruption of productive infection decreased rather than increased the proportion of apoptotic cells. Productive infection was accompanied by the early efflux of cytochrome c from the mitochondria in a proportion of cells and by activation of DEVD-specific caspases. Inactivation of caspase-9 resulted in a marked, but incomplete, prevention of the apoptotic response of these cells to viral infection. Thus, the poliovirus-triggered apoptotic program in L20B cells was not completely suppressed by the viral antiapoptotic functions. In contrast, human rhabdomyosarcoma RD cells did not develop appreciable apoptosis during productive or abortive infection, exhibiting inefficient efflux of cytochrome c from mitochondria and no marked activation of DEVD-specific caspases. The cells were also refractory to several nonviral apoptosis inducers. Nevertheless, typical caspase-dependent signs of apoptosis in a proportion of RD cells were observed after cessation of viral reproduction. Such "late" apoptosis was also observed in productively infected HeLa cells. In addition, a tiny proportion of all studied cells were TUNEL positive even in the presence of a caspase inhibitor. Degradation of DNA in such cells appeared to be a postmortem phenomenon. Biological relevance of variable host responses to viral infection is discussed.     

Effect of oxidized fibrinogens on blood coagulation

We studied the effect of UV-irradiated fibrinogen on blood coagulation. Fibrinogen with oxidation degree of 10% moderately activated the intrinsic pathway, but inhibited the extrinsic pathway of blood coagulation. Fibrinogen with oxidation degree of 20% inhibited both the extrinsic and intrinsic blood coagulation pathways. We revealed disturbances in the formation of fibrin clot with oxidized fibrinogen, suppression of platelet aggregation mediated by collagen receptors, and inhibition of aggregation associated with von Willebrand factor activity. ADP initiated platelet aggregation, which was in direct proportion to the degree of fibrinogen oxidation. Our results indicate that oxidized fibrinogen produces a dysregulatory effect on platelets. Translated fromByulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 138, No. 9, pp. 277–279, September, 2004     

Effect of antibodies to nerve growth factor and serum albumin on the development and behavior of mice

We studied physical development, behavioral characteristics, and learning capacity in the off-spring of mice immunized with nerve growth factor and bovine serum albumin. High titer of antibodies to these factors in the blood of pregnant females determines high levels of these antibodies in the blood of their pups. These changes modulate physical development, behavior, and learning capacity of rat pups. The effects of these antibodies differed in the strength and directionality. Antibodies to nerve growth factor more markedly retarded physical development, reduced learning capacity, and considerably increased pain thresholds in animals. Translated fromByulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 138, No. 7, pp. 98–100, July, 2004     

Comparison of once-daily atazanavir with efavirenz, each in combination with fixed-dose zidovudine and lamivudine, as initial therapy for patients infected with HIV

BACKGROUND: Atazanavir, an azapeptide protease inhibitor (PI), has pharmacokinetics that allow once-daily dosing, and it is not associated with significant PI-associated dyslipidemia. METHODS: A randomized, double-blind, double-dummy, active-controlled, 2-arm study comparing the antiviral efficacy and safety of atazanavir 400 mg administered once daily with efavirenz 600 mg administered once daily in combination with open-label fixed-dose zidovudine plus lamivudine twice daily. The 810 treatment-naive patients were stratified by HIV RNA level. The primary efficacy end point was the proportion of treated patients with HIV RNA levels <400 copies/mL through week 48. RESULTS: At week 48, HIV RNA levels were <400 copies/mL in 70% of patients receiving atazanavir and 64% of patients receiving efavirenz (intent-to-treat, difference; 95% confidence interval: 5.2%; -1.2%, 11.7%). Median CD4 cell counts increased at comparable magnitudes and rates in the 2 treatment arms (mean change at week 48: 176 cells/mm with atazanavir, 160 cells/mm with efavirenz). Atazanavir-treated patients relative to comparator-treated patients did not demonstrate significant increases in total cholesterol, fasting low-density lipoprotein cholesterol, or fasting triglycerides over 48 weeks of therapy. Atazanavir-linked bilirubin elevations infrequently resulted in treatment discontinuation (<1%). Atazanavir treatment did not increase fasting glucose or insulin levels. CONCLUSIONS: For initial HIV treatment, a highly active antiretroviral therapy regimen of atazanavir/zidovudine/lamivudine is as efficacious and well tolerated as the combination of efavirenz/zidovudine/lamivudine.