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Biomedical subjects

I Petri

Publications and source records attributed to I Petri.

53 records · Page 3Linked to original sources
PubMed1980

On the interaction of caffeine with nucleic acids. III. 1H NMR studies of caffeine--5'-adenosine monophosphate and caffeine-poly(riboadenylate) interactions.

1) The self-association of both caffeine (Cf) and 5'-adenosine monophosphate (AMP) in aqueous solution has been reinvestigated by 1H NMR. The self-association process is characterized by an isodesmic model. The apparent self-association constants of the vertical stacking process are KCf = (10.6 +/- 1.0) M-1 and KAMP = (1.67 +/- 0.17) M-1. The arrangement of the monomeric units in the stacked aggregates is discussed in terms of isoshielding curves theoretically calculated by Giessner-Prettre and Pullman. Models are proposed which are consistent with these and further previous NMR data. 2) The interaction of Cf and AMP has been studied by 1H NMR. The apparent association constant of the complex Cf-AMP is KC-A = (7.3 +/- 1.2) M-1. Two models of the mutual arrangement of AMP and Cf in the complex are proposed on the basis of the calculated isoshielding curves considering both ring current and local atomic diamagnetic anisotropy effects. 3) The interaction of Cf and poly(riboadenylate), (rA)n, is indicated by a downfield shift of the H-8 line but an upfield shifts of the H-2 line in the 1H NMR spectra of (rA)n. The concentration dependence of the 1H NMR shifts of both Cf and (rA)n can be explained by the existence of two binding mechanisms. We suggest (i) partial insertion of Cf between adjacent base residues of ordered single-stranded regions of (rA)n and (ii) outside binding of Cf in form of monomeric Cf as well as of self-associated aggregates. The complex geometry of insertion proposed on the basis of the calculated isoshielding curves is characterized by a stronger overlapping of the Cf ring and the H-2 proton of (rA)n as compared to the H-8 proton.

Adenosine Monophosphate↗
PubMed1980

Cellular immune function in patients with cancer of the upper part of the gastrointestinal tract.

Lymphocytes of 30 patients were examined for cellular immune function one day prior to operation. In 11 patients the tests were repeated six weeks after surgery. In comparison with 26 healthy blood donors the E rosette values were strongly reduced in the patients group. The zymosan-complement rosette counts were significantly lower if percentages were compared, but not significant when they were expressed in absolute numbers. Lymphocyte transformation tests revealed significant differences between the patients and control cases with all three mitogens applied (PHA, ConA, PWM). In the 11 patients with the tests repeated after operation, the effect of autologous plasma on the cultures was also studied. The main tendency was inhibition but in some cases the patients' plasma enhanced the reaction. Killer cell activity by ADCC was significantly lower in patients' than in the healthy donors' lymphocytes in different target-effector cell ratios.

Animals↗
PubMedDate not supplied

Genotype screening for hereditary hemochromatosis among voluntary blood donors in Hungary.

Hereditary hemochromatosis (HH) is a common genetic disorder. Although it is inherited in an autosomal recessive manner, heterozygous individuals are believed to be protected against iron deficiency. Screening to estimate the prevalence of HH was frequently performed among blood donors, not considering that carriers of the HH gene mutations may be present in higher proportion in this population. To examine the allele frequencies of the HH gene (HFE) point mutations, C282Y and H63D genotyping was carried out in 996 consecutive, first-time, and regular Hungarian blood donors by PCR-RFLP techniques. Iron parameters of the first-time donors and the identified C282Y heterozygotes and age, gender, and number of previous blood donation-matched wild-type donors were also determined. We were not able to demonstrate a significant increase in the frequency of C282Y and H63D alleles among regular blood donors, compared to first-time blood donors. However, there was a trend of higher C282Y allele frequency among women with higher number of previous blood donations (2.2 +/- 1.5% in female blood donors with 0-8 previous blood donations compared to 4.8 +/- 2.3% in women with more than 8 previous blood donations, P = 0.06). No detectable phenotypic differences were observed in serum iron, ferritin, and transferrin saturation values between C282Y wild-type and heterozygous groups. However, the single identified C282Y homozygous male (age 21) showed definite signs of iron overload. Our observations suggest that the protective effect of C282Y heterozygosity against iron deficiency may be less significant than other environmental (e.g., iron-rich diet) or genetic factors.

Adolescent↗
PubMedDate not supplied

[Calcium heparin-induced immunologic thrombocytopenia complicated with venous gangrene of the legs. Report of a clinical case].

An 80-year-old woman was admitted to the Traumatologic Hospital of Florence because of bilateral post-traumatic humeral fractures. Subcutaneous calcium heparin was immediately administered to prevent deep venous thrombosis. Nine days later, the patient was referred to the Internal Medicine Unit because of severe immune-mediated heparin-induced thrombocytopenia and bilateral deep venous thrombosis. Heparin therapy was immediately discontinued, and the patient was switched to warfarin therapy. Diagnosis of heparin-induced thrombocytopenia was confirmed by positivity of anti-heparin-PF4 antibodies. On the second day of warfarin therapy, bilateral limb venous gangrene with a high risk of limb amputation appeared. To reduce thrombin generation, i.e., the mechanism by which heparin-induced thrombocytopenia induces thrombotic events, intravenous treatment with dermatan sulphate and low-dose urokinase was initiated. After 10 days of treatment, the limb venous gangrene disappeared, and low-dose warfarin therapy was again introduced. The patient was discharged 40 days after admission, and a Doppler ultrasound study showed only minimal signs of deep vein thrombosis in the right popliteal veins. Although in Italy the use of dermatan sulphate has been limited to the prevention of deep vein thrombosis, this case shows that it should be considered a useful agent for the treatment of thrombotic complications secondary to heparin-induced thrombocytopenia. Patients with acute immune-mediated heparin-induced thrombocytopenia should not be treated with warfarin alone. Frequent platelet count monitoring from day 5 of heparin treatment remains the best means of early detection of immune-mediated heparin-induced thrombocytopenia.

Aged↗
PubMedDate not supplied

Immunomodulation activity of phenothiazines, benzo[a]phenothiazines and benz[c]acridines.

Some non-differentiation-induction benzo[a]phenothiazines and mutagenic benz[c]acridines more potently inhibited the mitogen-induced blast transformation of human-peripheral blood lymphocytes than differentiation-induction and non-mutagenic counterparts and phenothiazines. Differential absorption spectrophotometry revealed tight complex formation between these drugs and bacterial endotoxin or mitogens. All of these compounds only slightly affected antibody dependent cellular cytotoxicity and natural killer cell activity, but significantly inhibited the endotoxin-or heat-killed Staphylococcus aureus induced tumor necrosis factor production by human mononuclear cells. Pretreatment of mice with these drugs protected them from lethal E. coli infection. Quantumchemical analysis suggests a correlation between the biological activity of these compounds and some molecular orbital parameters such as the charge at C7, and the ratio of polar/total surface areas.

Acridines↗
PubMedDate not supplied

Effects of acridines on bacterial plasmid replication and endotoxin.

Different amino- and imino-acridines were systematically synthesized. The antibacterial, antiplasmid, antimotility and endotoxin complexing effect of acridines were studied, when antibacterial effect of the compounds was compared on E. coli. Aminoderivatives were more active than imino-acridines. The N-heptyl-9-imino-acridine was able to select lon minus mutants in the E. coli culture, however, the other acridines tested were ineffective in this respect. The iminoacridines inhibited the motility of Proteus vulgaris more effectively than aminoderivatives. The antimotility action of the acridines was also dependent on the ionic content of the media. The antiplasmid effect was measured on an F-prime plasmid of E. coli LE140 strain. Iminoacridines had a more powerful antiplasmid effect than the amino-substituted derivatives. The majority of the compounds inhibited the intercellular plasmid transfer from E. coli. Kmr donor to a Na-azide resistant recipient. In this test the aminosubstituted derivatives were shown to be more effective inhibitors of conjugation than the imino-substituted compounds. Endotoxin formed complexes with N-butylamino. N-propy-lamino and imidoderivatives. However, complex formation of N-ethyl-, N-heptyl-, N-diethylaminoethyl- and N-diethylamino-propyl-acridines were different. Correlations between molecular orbitals and the antibacterial effects are also discussed.

Acridines↗