RESUMEN

The purpose of the present study is to deepen our knowledge about the painting materials and technology characteristics of iconography during the Bulgarian National Revival. Our efforts have focused on studying the murals in the catholicon (main church) "The Nativity of the Virgin" of the Rila Monastery, which is one of Bulgarian leading historical monuments. A series of micro samples from the altar mural paintings were analyzed by a combination of attenuated total reflectance Fourier transform infrared (ATR-FTIR), micro-Raman spectroscopy, scanning electron microscopy energy dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Optical microscopy (OM). The data analysis showed that the painter's palette is made up of nine mineral pigments: smalt, chrome yellow, emerald green, vermilion, red lead, green earths, yellow ochre, sienna and calcite. The impression of rich colorful palette was achieved by using various pigment mixtures. The presence of egg binder in many paint samples suggested that the murals were executed by the traditional egg tempera technique, with the only exception of the smalt paint of the background where carbohydrate glue is present as binder.

RESUMEN

Although fragmentation of DNA has been observed in cells undergoing freezing procedures, a mutagenic effect of sub-zero temperature treatment has not been proved by induction and isolation of mutants in nuclear DNA (nDNA). In this communication we supply evidence for mutagenicity of freezing on nDNA of Saccharomyces cerevisiae cells. In the absence of cryoprotectors, cooling for 2 h at +4°C and freezing for 1 h at -10°C and 16 h at -20°C, with a cooling rate of 3°C/min, resulted in induction of frame-shift and reverse mutations in microsatellite and coding regions of nDNA. The sub-zero temperature exposure also has a strong recombinogenic effect, evidenced by induction of gene-conversion and crossing-over events. Freezing induces mutations and enhances recombination with a frequency equal to or higher than that of methylmethanesulphonate at comparable survival rates. The signals for the appearance of nDNA lesions induced by freezing are detected and transduced by the DNA damage pathway. Extracellular cryoprotectors did not prevent the mutagenic effect of freezing, while accumulation of trehalose inside cells reduced nDNA cryodamage. Freezing of cells is accompanied by generation of high ROS levels, and the oxidative stress raised during the freeze-thaw process is the most likely reason for the DNA damaging effect. Experiments with mitochondrial rho⁻ mutants or scavengers of ROS indicated that mutagenic and recombinogenic effects of sub-zero temperatures can be decreased but not eliminated by reduction of ROS level. The complete protection against cryodamage in nDNA required simultaneous usage of intracellular cryoprotector and ROS scavenger during the freeze-thaw process.

Asunto(s)

RESUMEN

The interaction of monogalactosyldiacylglycerol (MGDG) with cytochrome b(6)f complex (cyt b(6)f), a major component of the photosynthetic apparatus, was studied in Langmuir monolayers during compression/expansion cycling and at constant surface pressure mode. The surface pressure/area isotherms of the mixed films were analyzed in terms of surface compressional modulus and two-dimensional virial equation of state. The morphology and the surface potential of the monolayers were monitored by Brewster angle microscopy and vibrating plate sensor respectively. Our results suggested that there is a specific interaction between MGDG and cyt b(6)f which resulted in depletion of lipid molecules from the interface. The current work sheds light on the still unclear question how b(6)f complex gets in touch with the major compound of the thylakoid membranes, the non-charged lipid MGDG. The interaction occured even at very low sub-nanomolar concentration of the complex. This effect most probably could be attributed to hydrogen bonding between the galactose headgroup of the lipid and the protein moiety of cyt b(6)f.

Asunto(s)

RESUMEN

The aim of this study was to test for the efficacy and safety of the use of aglepristone for pregnancy termination on day 45 in cats. Six healthy cats were treated with 10 mg/kg aglepristone sc on day 45 and 46 after mating; six other cats served as untreated controls. The effect of treatment was monitored by general examination, vaginal cytology, ultrasonography and blood sampling for haematology and progesterone determination. Besides, interoestrus interval and next pregnancy including litter size were recorded. The efficacy of treatment was approximately 67% (4/6) with abortion occurring 4-7 days after the first injection and a sanguineous discharge and erythrocytes in vaginal smears for at least 6 days afterwards. The two treated cats that did not abort gave birth to two kittens on day 67 and had a stillbirth of a single kitten on day 71, respectively. As expected enlargement of the mammary glands and lactation were observed in all treated cats. No other treatment-induced side effects were observed. Progesterone levels at abortion were high (30-140 nmol/l), but were decreased on day 55. Aglepristone treatment did not affect fertility in following cycles. Finally, it can be concluded that late-term pregnancy termination with aglepristone is possible but due to a success rate of 67% an ultrasonographical examination 7 days after treatment is an inherent necessity to control the effect of treatment.

Asunto(s)

RESUMEN

Ty1 is a retrotransposon of the yeast Saccharomyces cerevisiae whose transposition at new locations in the host genome is activated by stress conditions, such as exposure to UV light, X-rays, nitrogen starvation. In this communication, we supply evidence that cooling for 2 h at +4 degrees C followed by freezing for 1 h at -10 degrees C and 16 h at -20 degrees C also increased Ty1 transposition. The mobility of Ty1 was induced by cooling at slow rates (3 degrees C/min) and the accumulation of trehalose inside cells or the cooling at high rates (100 degrees C/min) inhibited significantly the induction of the transposition. The freeze-induced Ty1 transposition did not occur in mitochondrial mutants (rho-) and in cells with disrupted SCO1 gene (Deltasco1 cells) evidencing that the Ty1 transposition induced by cooling depends on the mitochondrial oxidative phosphorylation. We also found that the freeze induced Ty1 transposition is associated with increased synthesis and accumulation of superoxide anions (O2-) into the cells. Accumulation of O2- and activation of Ty1 transposition were not observed after cooling of cells with compromised mitochondrial functions (rho-, Deltasco1), or in cells pretreated with O2- scavengers. It is concluded that (i) elevated levels of reactive oxygen species (ROS) have a key role in activation the transposition of Ty1 retrotransposon in yeast cells undergoing freezing and (ii) given the deleterious effect of increased ROS levels on cells, special precautions should be taken to avoid ROS production and accumulation during cryopreservation procedures.

Asunto(s)

RESUMEN

Using microelectrophoresis and electric light scattering techniques, we investigated the adsorption characteristics, surface coverage and surface electric parameters of superstructures from two isoforms of plastocyanin, PCa and PCb, in an oxidized state adsorbed on beta-ferric hydrous oxide particles. The surface electric charge and electric dipole moments of the composite particles and the thickness of the protein adsorption layer are determined in a wide pH range, at different ionic strengths and concentration ratios of PC to beta-FeOOH. The adsorption of the two proteins was found to shift the particles' isoelectric point and to alter the total electric charge and the electric dipole moments of the oxide particles to different extent. A "reversal" in the direction of the permanent dipole moment is observed at lower pH for PCb- than for PCa-coated oxide particles. Strict correlation is found between the changes in the electrokinetic charge of the composite particles and the variation in their "permanent" dipole moments. Data suggest that the adsorption of the proteins is driven by electrostatic and/or hydrophobic interactions with the oxide surfaces dependent on pH. The adsorption behaviour is consistent with the involvement of the "eastern" and "northern" patches of the plastocyanin molecules in their adsorption on the oxide surfaces that are differently charged depending on pH.

Asunto(s)

RESUMEN

An 11-year-old female German Shepherd dog was presented for investigation of progressive enlargement of the abdomen, periodic bloody discharge from the vulva and rapid exhaustion. Transabdominal ultrasonography and lateral abdominal radiography demonstrated an echogenic formation with anechogenic cavities located cranial to the urinary bladder and a homogeneous shadow with an elliptical shape was located caudal to the rib arc. Both showed indistinct borders. Exploratory laparotomy identified bilateral ovarian masses and ovariohysterectomy was performed. Histopathology confirmed ovarian cystadenocarcinoma. The dog remained clinically normal without evidence of metastatic disease 4 months after surgery. Papillary cystadenocarcinoma in the bitch could affect both ovaries and manifests with a rapid growth rate and clinical signs such as rapid exhaustion, abdominal enlargement and vulval discharge. Ovariohysterectomy is the treatment option.

Asunto(s)

RESUMEN

The stability of the two isoforms of poplar plastocyanin (PCa and PCb) was studied with differential scanning calorimetry (DSC) technique. It was shown that the thermal unfolding of both isoforms is an irreversible process with two endothermic and one exothermic peaks. The melting temperature of PCb was found to be 1.3+/-0.2 K degrees higher than of PCa, which indicates that PCb is more stable. The enthalpy of unfolding was estimated from the heat capacity curves and was found to be significantly higher for PCb at salt concentration I=0.1 M. In addition, PCb unfolding enthalpy and melting temperature are much more sensitive to the changes in the salt concentration as found in the experiments done at different ionic strength. The experiments were complemented with numerical calculations. The salt effect on the stability was modeled using the X-ray structure of PCa and a homology modeled structure of PCb. It was found, in agreement with the experimental data, that the stability of PCb changes by 4.7 kJ more than PCa, as the salt concentration increases from zero to 0.1 M. Thus, the differences in only 12 amino acid positions between "a" and "b" isoforms result in a measurable difference in the folding enthalpy and a significant difference in the salt dependence. The optimization of the electrostatic energies of PCa and PCb were studied and it was shown that PCb is better electrostatically optimized.

Asunto(s)

RESUMEN

A detailed study of the tyrosine spectral characteristics was carried out in a broad range of pHs for both isoforms of plastocyanin from poplar. It was found that Tyr 80 is always protonated while Tyr 83 can form a tirosinate at high pHs. The pK(a) of Tyr 83 is practically identical in plastocyanin a and b, but the quenching of its spectrum is different in the isoforms. This provides insights that the acidic patches surrounding Tyr 83 have different electrostatic properties in plastocyanin a and b. The protonation states and the electrostatic interactions were numerically modeled on the existing plastocyanin a structure and on a homology model of plastocyanin b. The results of numerical calculations agree with the experimental findings and identify several differences in the titration behavior of the acidic patches. The difference of the tyrosine quenching pH profiles of the isoforms is rationalized by the differences in the calculated pK(a)'s of amino acids in the neighboring acidic clusters.

Asunto(s)

RESUMEN

The goal of this issue is to assess the level of compliance, respectively of non-compliance among pharmacY patients between the years 2001 and 2002 in Sofia, Bulgaria. The authors study and emphasize on the factors that influence the non-compliance of the patients and also try to find different ways to increase the rate of compliance in Bulgaria. Two types of standard individual questionnaires are applied for assessment of the state of compliance and non-compliance among the pharmacy patients. The obtained results show that the main reasons, influencing the non-adherence of the patients are: the high average price of the drugs, the overload daily regimen, inattention, distrust to the treatment and others. The drug form appears to be one of the main factors that cause non-compliance, especially when the patients receive more than one drug in different drug forms few times a day and especially if elderly patients are addressed. Despite the presented comparatively high level of compliance among the patients (from 53% for 2001, to 82% for 2002), there are strategies to enhance compliance that have to be initiated. They incorporate communication tactics, patient's education, and proper dosage of the drugs and scheduling of the drug application. The results of the analysis of the received data show an increase in the level of compliance for the pharmacy patients in Bulgaria. For 2001 it was 53%, while for 2002 it has increased to 82%. This fact shows the influence of strategies for improvement of compliance.

Asunto(s)

RESUMEN

Hydrogels, based on polyacrylic acid and various macrodiisocyanates that contain polyethylene glycol, polypropylene glycol or polytetramethylene glycol in the main chain are synthesized. The obtained hydrogels are studied as possible polymer carriers of drug substances. Etophylin was applied as a model drug. It is exposed that the etophylin release rate from the hydrogel depends on the way of drug comprise in the polymer net, from its density from the chemical nature of the crosslinking agent and from the pH of the environment. The carried out studies let us to conclude that the obtained hydrogels are possible materials as drug carriers.

Asunto(s)

RESUMEN

This issue is an attempt to be compared the compliance, respectively non-compliance among pharmacy patients between the years 1998 and 2001. The authors make an attempt to elucidate the factors that influence the non-compliance of the patients in order to improve it and to increase the rate of compliance among them. A questionnaire is applied for assessment the state of compliance and non-compliance among the pharmacy patients. The results of the analysis of the received data show that the level of compliance was 69% in 1998 and has decreased to 53% in 2001. The main reasons that influence the non-adherence of the patients are shown.

Asunto(s)

RESUMEN

AIMS: To evaluate the lytic activities of crude enzymes from Cytophaga sp. LR2 on Rhodella reticulata cells and isolated algal polysaccharide. METHODS AND RESULTS: The Cytophaga compartment was separated after centrifugation in a cell suspension for 30 min at 18,000 g. The extracellular enzyme was obtained from the supernatant and the intracellular from the pelleted cells after sonication and removal of debris. Algal cells were incubated with extra- or intracellular preparations and sowed onto agar medium. The suppressive effect of the extracellular enzyme on colony-forming units was found to be almost twice as high. The result was still more pronounced when treated cells had been shocked osmotically before seeding. Saccharolytic activity was evaluated by changes in the reducing sugars in the media. Concerning isolated algal polysaccharide, the reducing power of the two bacterial preparates was relatively low. A combined fraction showed the highest lytic activity. Using native and SDS electrophoresis some relation between the prevalence of the extra and intracellular protein patterns was registered. Two of the common components' molecular weight masses of 50 and 21 kDa were found to be reproducible in native- and SDS-containing gel. CONCLUSIONS: Cytophaga sp. LR2 produce extra- and intracellular enzymes active in destroying Rhodella cultures. The agents excreted in the medium are more effective.We suppose that two or three different classes of enzymes are involved in the lysis process. The comparative electrophoresis in this case shows the protein components with predictable functions. SIGNIFICANCE AND IMPACT OF THE STUDY: Combining different simple and reproducible approaches to identify the lytic capability of Cytophaga sp. LR2 on R. reticulata.

Asunto(s)

RESUMEN

BACKGROUND: Early assessment of antiretroviral drug efficacy is important for prevention of the emergence of drug-resistant virus and unnecessary exposure to ineffective drug regimens. Current US guidelines for changing therapy are based on measurements of plasma HIV-1 RNA concentrations 4 or 8 weeks after the start of treatment with cut-off points of 0.75 or 1.00 log, respectively. We investigated the possibility of assessing drug efficacy from measurements of plasma HIV-1 concentrations made during the first week on therapy. METHODS: The kinetics of virus decay in plasma during the first 12 weeks of treatment was analysed for 124 HIV-1-infected patients being treated for the first time with a protease inhibitor. Patients with a continuous decline of HIV-1 concentrations and in whom HIV-1 was either undetectable or declined by more than 1.5 log at 12 weeks were defined as good responders; the rest were poor responders. FINDINGS: The individual virus decay rate constants (k) at day 6 correlated significantly (r>0.66, p<0.0001) with changes in HIV-1 concentrations at 4, 8, and 12 weeks, and correctly predicted 84% of the responses with a cut-off value of k=0.21 per day (in log scale). Reduction in plasma HIV-1 of less than 0.72 log by day 6 after initiation of therapy predicted poor long-term responses in more than 99% of patients. INTERPRETATION: These results suggest that changes in HIV-1 concentration at day 6 after treatment initiation are major correlates of longer-term virological responses. They offer a very early measure of individual long-term responses, suggesting that treatment could be optimised after only a few days of therapy.

Asunto(s)

RESUMEN

Clinical observations indicate that some autoimmune diseases, such as rheumatoid arthritis and multiple sclerosis, frequently remit during pregnancy but exacerbate, or have their onset, in the postpartum period. The immune basis for these phenomena is poorly understood. Recently, excessive production of IL-12 and TNF-alpha was causally linked to rheumatoid arthritis and multiple sclerosis. We studied 18 women with normal pregnancies in their third trimester and during the early postpartum period. We report that during the third trimester pregnancy, ex vivo monocytic IL-12 production was about 3-fold and TNF-alpha production was approximately 40% lower than postpartum values. At the same time, urinary cortisol and norepinephrine excretion and serum levels of 1,25-dihydroxyvitamin were 2- to 3-fold higher than postpartum values. As shown previously, these hormones can directly suppress IL-12 and TNF-alpha production by monocytes/macrophages in vitro. We suggest that a cortisol-, norepinephrine-, and 1,25-dihydroxyvitamin-induced inhibition and subsequent rebound of IL-12 and TNF-alpha production may represent a major mechanism by which pregnancy and postpartum alter the course of or susceptibility to various autoimmune disorders.

Asunto(s)

RESUMEN

The effect of electrostatic interactions on the conformation and thermal stability of plastocyanin (Pc) was studied by infrared spectroscopy. Association of any of the two redox states of the protein with positively charged membranes at neutral pH does not significantly change the secondary structure of Pc. However, upon membrane binding, the denaturation temperature decreases, regardless of the protein redox state. The extent of destabilization depends on the proportion of positively charged lipid headgroups in the membrane, becoming greater as the surface density of basic phospholipids increases. In contrast, at pH 4.8 the membrane binding-dependent conformational change becomes redox-sensitive. While the secondary structures and thermal stabilities of free and membrane-bound oxidized Pc are similar under acidic conditions, the conformation of the reduced form of the protein drastically rearranges upon membrane association. This rearrangement does not depend on electrostatic interactions to occur, since it is also observed in the presence of uncharged lipid bilayers. The conformational transition, only observed for reduced Pc, involves the exposure of hydrophobic regions that leads to intermolecular interactions at the membrane surface. Membrane-mediated partial unfolding of reduced Pc can be reversed by readjusting the pH to neutrality, in the absence of electrostatic interactions. This redox-dependent behavior might reflect specific structural requirements for the interaction of Pc with its redox partners.

Asunto(s)

RESUMEN

The performance of 18 frontal lobe lesion (FL) and 10 frontal lobe dementia (FLD) patients on an associative memory test was compared with the performance of their matched normal controls. The FL group was severely impaired on cued and free recall and was moderately impaired on a recognition condition. Left FL patients performed the poorest on the cued and free recall conditions. The FLD patients were moderately impaired on the free recall condition only but there was a subgroup of FLD patients with additional left temporal atrophy who appeared severely impaired on both cued and free recall. These findings indicate that both left frontal and temporal lobe damage can impair associative learning and that this impairment is more strikingly seen with free rather than cued recall.

Asunto(s)

RESUMEN

This study deals with Verapamil hydrochloride release from tablets based on high molecular weight poly(ethylene oxide) (PEO). The drug release proceeds as a controlled diffusion (n=0.44-0.47), which rate is dependent on the molecular weight of PEO. Independent from it, under the conditions of the Half-change test, the drug release practically ceases after 4 h as a result of obtaining low soluble in the water base. The introduction of hydrophilic polymers with pH dependent solubility (Eudragit L, Eudispert hv and Carbopol 934) at concentrations of 10/50% with respect to PEO amount keeping constant the ratio drug: matrix insures relatively complete release both in alkali medium and under the conditions of the Half-change test. Meanwhile drug release kinetics also changes - the release of all models studied runs as a typical abnormal diffusion (a=0.66-0.87), i. e. like a diffusion-relaxation controlled process. The decrease in drug concentration leads not only to retarded release of the drug sample but also to changes in the kinetics of the process. At lower drug concentrations on the matrix from a typical abnormal diffusion it turns into a relaxation controlled diffusion (n(10%)=1).

Asunto(s)

RESUMEN

The conformational changes associated with the redox transition of plastocyanin (PC) were investigated by absorption and reaction-induced infrared spectroscopy. In addition to spectral features readily ascribed to beta and turn protein secondary structures, the amide I band shows a major component band at 1647 cm(-1) in both redox states of the protein. The sensitivity of this component to deuteration and increasing temperature suggests that PC adopts an unusual secondary structure in solution, which differs from those described for other type I copper proteins, such as azurin and halocyanin. The conformations of oxidized and reduced PC are different, as evidenced (1) by analysis of their amide I band contour and the electrochemically induced oxidized-minus-reduced difference spectrum and (2) by their different thermal stability. The redox-induced difference spectrum exhibits a number of difference bands within the conformationally sensitive amide I band that could be assigned to peptide C=O modes, in light of their small shift upon deuteration, and to signals attributable to side chain vibrational modes of Tyr residues. Lowering the pH to 4.8 induces destabilization of both redox states of the protein, more pronounced for reduced PC, without significantly affecting their secondary structure. Besides the conformational differences obtained at neutral pH, the oxidized-minus-reduced difference spectrum shows two broad and strong negative bands at 1405 and 1571 cm(-1), assigned to COO(-) vibrations, and a broad positive band at 1710 cm(-1), attributed to the C=O vibration of a COOH group(s). These bands are indicative of a protonation of (an) Asp or Glu side chain(s) upon plastocyanin oxidation at acidic pH.

Asunto(s)

RESUMEN

Concept formation and shifting abilities of 17 frontal lesion (FL) and 8 Parkinson's disease (PD) patients were assessed with the California Card Sorting Test. FL patients demonstrated a significantly greater number of perseverative responses and deficits in strategy planning, strategy initiation, and concept formation and did not benefit from abstract cues in comparison with their matched normal control (NC) participants. PD patients also demonstrated an increased number of perseverative responses under selected conditions in comparison with their matched NCs, but their ability to explain their sorts, to extract and express the sorting principles, and to sort with the help of abstract and concrete cues depended on their general cognitive status.

Asunto(s)