Search PubMed⌕ Search

Biomedical subjects

I Petri

Publications and source records attributed to I Petri.

At least 19 recordsLinked to original sources

First solvation shell of the Cu(II) aqua ion: evidence for fivefold coordination.

We determined the structure of the hydrated Cu(II) complex by both neutron diffraction and first-principles molecular dynamics. In contrast with the generally accepted picture, which assumes an octahedrally solvated Cu(II) ion, our experimental and theoretical results favor fivefold coordination. The simulation reveals that the solvated complex undergoes frequent transformations between square pyramidal and trigonal bipyramidal configurations. We argue that this picture is also consistent with experimental data obtained previously by visible near-infrared absorption, x-ray absorption near-edge structure, and nuclear magnetic resonance methods. The preference of the Cu(II) ion for fivefold instead of sixfold coordination, which occurs for other cations of comparable charge and size, results from a Jahn-Teller destabilization of the octahedral complex.

Journal Article↗

Defects in a disordered world: the structure of glassy GeSe2

The full set of partial structure factors for the prototypical network glass GeSe2 was measured using the method of isotopic substitution in neutron diffraction. The basic building block of the network is the Ge(Se(1/2))(4) tetrahedron in which 34(5)% of the Ge reside in edge-sharing configurations. The intrinsic chemical order of the glass is, however, broken with a maximum of 25(5)% Ge and 20(5)% Se being involved in homopolar bonds at distances of 2.42(2) and 2.32(2) A, respectively.

Journal Article↗

[A new method of molecular testing in the differential diagnosis of hereditary hemochromatosis].

Hereditary hemochromatosis is an autosomal, recessive disorder of the iron metabolism. The hemochromatosis gene (HFE) was previously located on chromosome 6 and recently identified by positional cloning. A point mutation, C282Y, was found to be present in the HFE gene in homozygous form in 64 to 100% of patients with established hemochromatosis. The relationship of a second polymorphic variant of the HFE gene, H63D to the formation of iron overload is debated. Although hemochromatosis is one of the most common inherited disorders among Caucasians, in the absence of specific signs it is rarely diagnosed. In order to obtain comparable epidemiological data for Hungary, we tested 1271 and 277 randomly selected, unrelated, healthy subjects for C282Y and H63D respectively. In addition C282Y testing was carried out in 58 patients suffering from liver cirrhosis, and in 191 individuals with suspected hemochromatosis. For C282Y and H63D mutation analyses polymerase chain reaction technique followed by Rsa I and Bcl I restriction enzyme digestion was used. We developed an alternative method for the detection of C282Y based on an amplification-generated Kpn I restriction site. The allele frequencies were 3.8% and 12.3% for C282Y and H63D respectively in the normal Hungarian population. There was no significant difference in C282Y allele frequencies between liver disease patients (1.7%) and the normal population. We identified 15 homozygous and 25 heterozygous individuals among 191 individuals with suspected hemochromatosis. The C282Y and the H63D allele frequencies in the normal Hungarian population were found to be similar to the allele frequencies observed in other European populations, indicating that there is a large number of individuals susceptible for iron overload in Hungary (1:700). Mutation analysis is a novel, non-invasive method in the diagnostics of hereditary hemochromatosis, which increasingly becomes part of the routine clinical work.

Alleles↗

Extension of the protocol of OECD guideline 407 (28-day repeated dose oral toxicity test in the rat) to detect potential immunotoxicity of chemicals.

To indicate the immunotoxic potential of chemicals the examinations prescribed by OECD Guideline 407 were extended by the following additional toxicological, haematological, histopathological, and immune function examinations: absolute and relative organ weight of spleen, thymus, popliteal lymph nodes, lung and brain; histopathology of thymus, mesenteric lymph nodes, popliteal lymph nodes, bone marrow (femur), Peyer's patches (ileum), lungs and colon; PFC assay (spleen), T cell proliferation and NK cell assay. Two well known immunosuppressants Azathioprine (AZA) and Cyclosporine A (CysA) were chosen as model compounds at a dose range which do not cause visible toxic signs on the animals during a 28 days treatment period. The results show that the applied experimental system is much more sensitive in detection of the immunotoxic potential of these two compounds in a low dose range than the examination required by OECD Guideline 407 are.

Administration, Oral↗

[Evaluation of 3757 cases of open biliary tract surgery before the introduction of the laparoscopic method (basis for comparison)].

3757 elective nonmalignant biliary tract operations are evaluated retrospectively in the 17-year period from January 1, 1974 to December 31, 1990. The operations were divided into four periods according to development and frequency of intraoperative diagnostics: I. period without examinations of common bile duct (511 operations), II. selective period (848 operations), III. routine period (906 operations), IV. restricted routine period (1492 operations). The authors experienced improvement in their results if they carried out intravenous cholangiography routinely. Comparing eight characteristic factors they believe that their results are favourable if they performed intraoperative common bile duct examinations (manometry, cholangiography, flow rate measurement) in 39.6% rate and if they employed praeoperatively EST if necessary. They propose the selective intraoperative cholangiography. In the period of 39.6% intraoperative cholangiography (restricted routine period) they found common bile duct stones in 10.7%, unsuspected stones in 0.4%, retained stones in 1.6%, unnecessary choledochotomies in 2.7% and intraoperative common bile duct injuries in 0.2%. The overall mortality rate was 0.4%. They deal with the intraoperative differential diagnostics of Vater papilla stenosis and spasm.

Ampulla of Vater↗

HLA associated cytotoxic antibody production in dialyzed chronic uraemic patients.

We studied the level of the cytotoxic anti-HLA antibodies (CTA) in 90 hemodialyzed chronic uraemic patients who were on waiting list of transplantation. An association between alleles of HLA A1, B8, DR3 haplotype and the level of CTA was studied. The ratio of the reduced CTA producing subjects was significantly higher in the HLA B8 and DR3 carriers. We could observe the highest ratio in the joint appearance of these alleles. In the presence of HLA A1 allele the ratio was decreased beside B8 or DR3 even as joined attendance of these alleles. Our data suggest a different role of these linked antigens in the regulation of cytotoxic antibody production.

Adolescent↗

[Connection of immune status, nutritional status and postoperative complications in patients after surgery for organic esophageal stricture].

The postoperative complications were analysed in 64 patients after operation for stricture of the esophagus. The underfeeding in consequence of the esophagus stricture reduced the cellular immune functions and increased the operative risk. The comparison of the feeding and immune parameters of patients with benign and malign strictures of the esophagus showed that the poor immune reactivity is caused by the underfeeding first of all and not by the immune depression due the tumor.

Esophageal Neoplasms↗

Antimicrobial and immunomodulating effects of some phenolic glycosides.

Several phenolic glycosides, i.e. acteoside, desrhamnosyl acteoside, and purpureaside A, B and C, exerted weak antibacterial effects on Escherichia coli. Acteoside had antiplasmid effects, including F'lac plasmid elimination, and inhibited kanamycin resistance transfer in E. coli. Acteoside, desrhamnosyl acteoside and purpureaside A displayed antiviral effect on Aujeszky virus. All of the phenolic glycosides decreased some human leucocyte functions, including rosette formation, mitogen-induced blast transformation and phagocytic activity in vitro. The purpureaside C had significant proinflammatory action, however, other phenolic glycosides showed neither proinflammatory nor antiinflammatory effect on carrageenin-induced inflammation in vivo.

Animals↗

Comparative study of alloimmune reactions induced by leukocyte and platelet transfusions in humans: characteristic changes of activation markers, gamma interferon, and FcR blocking antibody production.

This study was undertaken to define immune responses induced by leukocyte and platelet transfusions. We offer evidence that activation by alloimmunization with intravenously administered "buffy coat" cells results in immune alterations similar to the early rejection episodes following kidney transplantation. Thus, IL-2 and HLA-DR expression increased on PBL 2 and 3 days after antigen exposure and paralleled elevations of IFN-gamma, neopterin, and beta 2 microglobulin levels. No significant changes were detected in the number of T-cell subpopulations. Alloimmunization by purified platelets alone that express only class I MHC antigens failed to induce the above alteration, even after repeated exposure. Repeated alloimmunization with "buffy coat" cells or isolated platelets stimulated a progressive increase up to 100% blocking activity on EA rosette formation. We conclude that the expression of activation markers on PBL and the production of IFN gamma and neopterin reflect the early phase of alloimmune response induced by leukocytes. This type of alloactivation is not a prerequisite for the development of FcR-blocking antibody, which is produced after pure platelet transfusion as well.

Binding, Competitive↗

Development of mathematical models for an in vitro-phagocytosis test system.

Phagocytosis tests have been carried out by many authors using different methods under different conditions. The results have been interpreted in different ways, as well sometimes with conflicting notations. In order to get to a more systematic data analysis and to separate intrinsic from methodic influences, the possibility to apply mathematical models to a phagocytosis test has been studied. In agreement with previous experiences that phagocytosis can well be represented by a mathematical treatment as Michaelis-Menten-type enzyme kinetics concerning its initial rate and by an exponential function under in vivo conditions, in vitro-phagocytosis was phenomenologically described as an analogon of an irreversible bimolecular chemical reaction. In this way, rate and capacity of phagocytosis may be quantified separately. On the basis of systematic deviations of the data from this model, modifications have been developed which could be connected with pertinent observations. The design of further experiments from preliminary results on the basis of our models is discussed.

Granulocytes↗

The effects of cannabinoids and cannabispiro compounds on Escherichia coli adhesion to tissue culture cells and on leukocyte functions in vitro.

delta 9-Tetrahydrocannabinol, cannabidiol, cannabidiolic acid, tetrahydrocannabidiolic acid, cannabispirol, acetylcannabispirol, cannabispirone, and cannabispirenone in a low concentration did not affect the adhesion of Escherichia coli on cultured HEp-2 cells. Cannabinoids at 10(-6) M increased the chemiluminescence of human polymorphonuclear leukocytes, while the cannabispiro compounds failed to enhance the oxidative burst of leukocytes. In lymphocyte and granulocyte function tests (E- and EA-rosette formation, blast transformation of T-lymphocytes in the presence of phytohaemagglutinin and concanavalin-A, ADCC and phagocytosis) all compounds displayed immunosuppressive effect at 1.5 X 10(-5) M. Tetrahydrocannabidiolic acid exerted the weakest immunosuppression on human leukocyte functions.

Antibody-Dependent Cell Cytotoxicity↗

Spontaneous and stimulated lymphocyte transformation test in homozygous children with cystic fibrosis.

Spontaneous and non-specific mitogenic stimulated lymphocyte transformation tests of cellular immune function were carried out. The phytohaemagglutinin, concanavalin A and pokeweed mitogen stimulated lymphocyte transformation was significantly diminished in the group of cystic fibrosis (CF) homozygotes as compared to the controls, as an indication of the impaired reactivity of the T-lymphocytes. The spontaneous phytohaemagglutin stimulated lymphocyte transformation ratio was diminished, too.

Adult↗

Comparison of the postoperative changes in the humoral and cellular immune activity in septic and non-septic colorectal cancer patients.

The effect of sepsis on the host resistance of 34 colorectal cancer patients with normal preoperative immune reactivity was studied. A significant change (p less than 0.01) was found in the IgG level of the septic patients (n = 13) when comparing their values with those of the non-septic patients (n = 21), on the third and 7th days postoperatively. There was no appreciable change in the IgA and IgM levels. The E rosette formation and the blast transformation values of the patients showed a marked decrease on the 7th day postoperatively. In the non-septic patients the normal initial values reappeared on the 10th postoperative day, while in the septic cases they significantly decreased as compared to both their own values and to those of the non-septic patients assessed during the same period (p less than 0.05). The possible factors serving for the prevention of decrease in the resistance of the host organism, are discussed.

Colonic Neoplasms↗

Antibody dependent cellular cytotoxicity (ADCC)-reaction and an in vitro steroid sensitivity test of peripheral lymphocytes in children with malignant haematological and autoimmune diseases.

ADCC reaction (antibody dependent cellular cytotoxicity), ADCC capacity and ADCC steroid sensitivity examinations were performed in 20 children with tumorous or haematological diseases, 10 children with autoimmune diseases, and appropriate controls, in order to establish the killer function and steroid sensitivity. In the above diseases a study was also made of the correlation of the individual reactions with the duration of steroid therapy. The two patient groups did not exhibit a significant difference from the controls as concerns the ADCC reaction and ADCC capacity. In the group of tumorous or malignant haematological diseases the steroid sensitivity behaved in a different way, with sensitivity in 45%, moderate sensitivity in 20%, and steroid resistance in 35% of the patients. Steroid inhibition of the ADCC reaction was significantly decreased in the group of autoimmune patients. There was no correlation between ADCC reaction and ADCC steroid sensitivity or resistance in either group, and thus the ADCC steroid resistance or sensitivity and lymphocyte killer function proved to be independent. No correlation was found between the steroid sensitivity or resistance and the duration of steroid treatment.

Adolescent↗