PubMed Health⌕ Search

Biomedical subjects

A Olczak

Publications and source records attributed to A Olczak.

12 recordsLinked to original sources
PubMed2006

Opportunistic infections and other AIDS-defining illnesses in Poland in 2000-2002.

BACKGROUND: The introduction of highly active antiretroviral therapy (HAART) led to a decreased incidence of the most severe opportunistic infections (OIs) in HIV-infected patients. In Poland, HAART became widely used in 1998. MATERIALS AND METHODS: This study was based on data from medical records data collected in the years 2000-2002 from medical centers for HIV-infected patients in Poland. The aim of the study was to determine the incidence of opportunistic infections (OIs) and other AIDS defining illnesses (ADIs). The chi(2) test was used to determine any significant trends. RESULTS: The incidence of ADIs was 6.8, 6.5 and 4.8/100 persons/year in 2000-2002, respectively. The most common diagnosed OIs were: fungal infections, tuberculosis, recurrent pneumonia, PCP and toxoplasmosis. In patients receiving HAART (HAART+) the incidence of ADIs was significantly lower than in non-ARV-treated as well as in all HIV+ (p < 0.02, p < 0.001, p < 0.001, respectively). A significant decrease in the incidence of ADIs in HAART+ patients between 2000 and 2002 (p < 0.0001) was observed. From 25% to 30% of ADIs among HAART+ patients were diagnosed within the first 3 months of antiretroviral therapy. In HAART+ patients the most common ADIs were fungal infections and tuberculosis. The diagnosis of ADIs resulted in the recognition of HIV status in 8.7-8.9% of patients. CONCLUSIONS: Five years after the introduction of HAART the incidence of ADIs had declined. Fungal infections and tuberculosis were the most common OIs in HIV+ patients in Poland.

AIDS-Related Opportunistic Infections↗
PubMed2005

Structure of gramicidin D-RbCl complex at atomic resolution from low-temperature synchrotron data: interactions of double-stranded gramicidin channel contents and cations with channel wall.

Gramicidin D (gD) is a naturally occurring ionophoric antibiotic that forms membrane channels specific for monovalent cations. The crystal structure of the RbCl complex of gD has been determined at 1.14 A resolution from low-temperature (100 K) synchrotron-radiation data with a final R of 16%. The structure was refined with anisotropic temperature factors for all non-H atoms and with partial occupancies for many of them. The asymmetric unit in the crystal contains four crystallographically independent molecules that form two right-handed antiparallel double-stranded dimers. There are seven distinct rubidium-binding sites in each dimeric channel. The occupancy factors of Rb cations are between 0.11 and 0.35 and the total ion contents of the two crystallographically independent channels are 1.59 and 1.22 ions, respectively. Although each channel is 'chemically symmetrical', the side-chain conformations, the distributions of rubidium cations and their binding sites in the two independent channels are not. Cations are 'coordinated' by delocalized pi-electrons of three to five carbonyl groups that together with peptide backbone chains form the gramicidin channel walls. The water:cation ratio in the channel interior is four or five:one, and five or six waters separate Rb cations during their passage through the channel.

Binding Sites↗
PubMed2004

Respiratory hydrogen use by Salmonella enterica serovar Typhimurium is essential for virulence.

Based on available annotated gene sequence information, the enteric pathogen salmonella, like other enteric bacteria, contains three putative membrane-associated H2-using hydrogenase enzymes. These enzymes split molecular H2, releasing low-potential electrons that are used to reduce quinone or heme-containing components of the respiratory chain. Here we show that each of the three distinct membrane-associated hydrogenases of Salmonella enterica serovar Typhimurium is coupled to a respiratory pathway that uses oxygen as the terminal electron acceptor. Cells grown in a blood-based medium expressed four times the amount of hydrogenase (H2 oxidation) activity that cells grown on Luria Bertani medium did. Cells suspended in phosphate-buffered saline consumed 2 mol of H2 per mol of O2 used in the H2-O2 respiratory pathway, and the activity was inhibited by the respiration inhibitor cyanide. Molecular hydrogen levels averaging over 40 microM were measured in organs (i.e., livers and spleens) of live mice, and levels within the intestinal tract (the presumed origin of the gas) were four times greater than this. The half-saturation affinity of S. enterica serovar Typhimurium for H2 is only 2.1 microM, so it is expected that H2-utilizing hydrogenase enzymes are saturated with the reducing substrate in vivo. All three hydrogenase enzymes contribute to the virulence of the bacterium in a typhoid fever-mouse model, based on results from strains with mutations in each of the three hydrogenase genes. The introduced mutations are nonpolar, and growth of the mutant strains was like that of the parent strain. The combined removal of all three hydrogenases resulted in a strain that is avirulent and (in contrast to the parent strain) one that is unable to invade liver or spleen tissue. The introduction of one of the hydrogenase genes into the triple mutant strain on a low-copy-number plasmid resulted in a strain that was able to both oxidize H2 and cause morbidity in mice within 11 days of inoculation; therefore, the avirulent phenotype of the triple mutant is not due to an unknown spurious mutation. We conclude that H2 utilization in a respiratory fashion is required for energy production to permit salmonella growth and subsequent virulence during infection.

Animals↗
PubMed2001

Structure of lobster apocrustacyanin A1 using softer X-rays.

The molecular basis of the camouflage colouration of marine crustacea is often provided by carotenoproteins. The blue colour of the lobster carapace, for example, is intricately associated with a multimacromolecular 16-mer complex of protein subunits each with a bound astaxanthin molecule. The protein subunits of crustacyanin fall into two distinct subfamilies, CRTC and CRTA. Here, the crystal structure solution of the A(1) protein of the CRTC subfamily is reported. The problematic nature of the structure solution of the CRTC proteins (both C(1) and A(1)) warranted consideration and the development of new approaches. Three putative disulfides per protein subunit were likely to exist based on molecular-homology modelling against known lipocalin protein structures. With two such subunits per crystallographic asymmetric unit, this direct approach was still difficult as it involved detecting a weak signal from these sulfurs and suggested the use of softer X-rays, combined with high data multiplicity, as reported previously [Chayen et al. (2000), Acta Cryst. D56, 1064-1066]. This paper now describes the structure solution of CRTC in the form of the A(1) dimer based on use of softer X-rays (2 A wavelength). The structure solution involved a xenon derivative with an optimized xenon L(I) edge f" signal and a native data set. The hand of the xenon SIROAS phases was determined by using the sulfur anomalous signal from a high-multiplicity native data set also recorded at 2 A wavelength. For refinement, a high-resolution data set was measured at short wavelength. All four data sets were collected at 100 K. The refined structure to 1.4 A resolution based on 60 276 reflections has an R factor of 17.7% and an R(free) of 22.9% (3137 reflections). The structure is that of a typical lipocalin, being closely related to insecticyanin, to bilin-binding protein and to retinol-binding protein. This A(1) monomer or dimer can now be used as a search motif in the structural studies of the oligomeric forms alpha- and beta-crustacyanins, which contain bound astaxanthin molecules.

Amino Acid Sequence↗
PubMed2000

Synchrotron X-ray reciprocal-space mapping, topography and diffraction resolution studies of macromolecular crystal quality.

A comprehensive study of microgravity and ground-grown chicken egg-white lysozyme crystals is presented using synchrotron X-ray reciprocal-space mapping, topography techniques and diffraction resolution. Microgravity crystals displayed reduced intrinsic mosaicities on average, but no differences in terms of strain over their ground-grown counterparts. Topographic analysis revealed that in the microgravity case the majority of the crystal was contributing to the peak of the reflection at the appropriate Bragg angle. In the ground-control case only a small volume of the crystal contributed to the intensity at the diffraction peak. The techniques prove to be highly complementary, with the reciprocal-space mapping providing a quantitative measure of the crystal mosaicity and strain (or variation in lattice spacing) and the topography providing a qualitative overall assessment of the crystal in terms of its X-ray diffraction properties. Structural data collection was also carried out at the synchrotron.

Crystallography, X-Ray↗
PubMed2000

Apocrustacyanin A1 from the lobster carotenoprotein alpha-crustacyanin: crystallization and initial X-ray analysis involving softer X-rays.

The A1 subunit of the carotenoprotein alpha-crustacyanin, isolated from lobster carapace, has been crystallized using the vapour-diffusion method. The crystals, grown in solutions of ammonium sulfate containing methylpentanediol (MPD), diffracted to 2. 0 A. The crystals are stable to radiation. The space group of the crystals is P2(1)2(1)2(1). The unit-cell parameters are a = 41.9, b = 80.7, c = 110.8 A. 'Standard structure determination' has been unsuccessful within this crustacyanin family. Instead, an approach based on the S atoms is being undertaken involving softer X-rays at the SRS, Daresbury.

Animals↗
PubMed1999

Oxidative DNA base damage in lymphocytes of HIV-infected drug users.

In the present study, we have studied the level of oxidative DNA base damage in lymphocytes of HIV-infected intravenous drug users (IDUs) and a seronegative control group. Chromatin was isolated from the lymphocytes and then analyzed by gas chromatography/isotope-dilution mass spectrometry with selected-ion monitoring (GC/IDMS-SIM). Significantly greater levels of four oxidatively modified DNA bases were observed in chromatin samples from the symptomatic HIV-infected patients than in those from the seronegative patients. These were 5-hydroxyuracil, 5-hydroxycytosine, 8-hydroxyadenine and 8-hydroxyguanine. In the case of 5-hydroxyuracil and 8-hydroxyguanine, a statistically significant difference was also found between the control group and the asymptomatic HIV-positive patients. These results suggest that oxidative stress may play an important role in the pathogenesis of acquired immune deficiency syndrome (AIDS), and that administration of antioxidant drugs to HIV-infected patients may offer protection against AIDS-related carcinogenesis.

Adenine↗
PubMed1995

[Efficacy of passive and active immunization against HBV infection in children with neoplastic diseases].

The efficacy of 3 schemes of passive and active prevention of HBV infection was evaluated in 47 children with haematologic proliferative diseases. Twenty-six children suffering from leukemia (group I) received passive immunisation (hepatitis B immunoglobulin) in six week intervals during intensive chemotherapy and were vaccinated on maintenance therapy. Thirteen children with Hodgkin or B-non-Hodgkin lymphoma (group II) received active immunisation from the beginning of intensive chemotherapy with two doses of immunoglobulin. Eight children who had completed their therapy (group III) were vaccinated only. Among children who completed vaccinations, 5/8 in group I, 4/7 in group II and 5/5 in group III produced protective anti-HBs levels. Passive/active prophylaxis was successful in most patients suffering from neoplastic diseases and reduced the endemy of HBV infection in our department from 43.3% to 2.56% infected subjects. Among 7 patients vaccinated from the beginning of treatment (group II), 4 of them produced protective levels of anti,-HBs, despite intensive chemotherapy.

Adolescent↗
PubMed1977

The role of histamine in wound healing I. The effect of high doses of histamine on collagen and glycosoaminoglycan content in wounds.

The effect of high doses of histamine (Hi) on collagen and glycosoaminoglycan (GAG) content in skin wounds of rats was studied on days 1, 3, 5, 10 and 14 after wounding. Injection of high doses of Hi into the wounded area inhibited colagen production, collagen polymerization and GAG synthesis; levels of chondroitin sulphates (chondroitin-4,6-sulphate and dermatan sulphate) and hyaluronic acid were decreased.

Animals↗
PubMedDate not supplied

The influence of sodium diethyldithiocarbamate (DDC) on serum lipids in the rabbit.

The influence of sodium diethyldithiocarbamate (DDC) on serum lipids in the rabbit. Acta Physiol. Pol., 1979, 30 (2): 327--329. The level of cholesterol, phospholipids and triglycerides in blood serum of rabbits treated with sodium diethyldithiocarbamate (DDC) was determined. DDC administration in daily doses of 100, 200 and 400 mg/kg, during 4 weeks, resulted in an increase of triglyceride and phospholipid levels changes were found in the serum cholesterol concentration.

Animals↗