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Biomedical subjects

I Földes

Publications and source records attributed to I Földes.

At least 73 records · Page 4Linked to original sources
PubMed1983

Isoelectric focusing of bacterial DNA methylases.

The multiplicity of bacterial DNA methylases has been shown for new microorganisms, Mycobacteria and Shigella, by a double-step procedure including column chromatography followed by isoelectric focusing of the total methylase fraction. The profiles of the DNA methylating activity of Sh. sonnei 47 and M. butyricum strains were studied. Sh. sonnei 47 cells were found to contain five different proteins responsible for DNA methylation and having pI 4.2, 5.3, 6.2, 8.4 and 9.2. Four M. butyricum methylases were represented by proteins with pI 4.2, 6.0, 8.0 and 9.0.

Chromatography, Affinity↗
PubMed1983

Effect of experimental patellar luxation on the knee joint in the rat.

In 16 male Wistar albino rats the patella was fixed to the lateral aspect of the lateral condylus of the femur. Animals with luxated knee joint and controls were sacrificed 7-9 months after surgery. Operated knee joints were processed for histology and subjected to morphometric analysis in comparison to the controls.- It was found that (1) the artificial disturbance of the femoro-patellar junction resulted in a severe destruction of articular cartilages of the tibio-femoral and femoro-patellar junction; (2) the destructions progressed with time; (3) there was no substantial difference between the changes of the medial and lateral articular surfaces of the femur and tibia; (4) changes comprised focal cartilage necrosis, widening of cartilaginous area under the tide-mark, proliferation of subchondral bone and formation of osteophytes; (5) the fact that a change of the statics of femoro-patellar junction leads to panarthrosis, moreover that articular capsule, menisci, epi-, meta-, and diaphyseal bone areas are also involved, indicate the complexity of the question. The findings indicated that changes of the femoro-patellar junction play a role in the degenerative processes of the knee joint. It is concluded that early recognition and treatment of femoro-patellar alterations may help in the prevention of knee panarthrosis.

Animals↗
PubMed1983

DNA-methylating activity of mycobacteria.

The methylating activity of the four mycobacterium strains Mycobacterium phlei, Mycobacterium smegmatis strain Butyricum, Mycobacterium smegmatis strain Rabinowitz, lysogenic Mycobacterium smegmatis strain Rabinowitz was studied in vitro. All the four strains were found to have methylating activity; enzyme containing extracts of M. smegmatis strain Butyricum and M. phlei showed a stronger activity than those of M. smegmatis strain Rabinowitz and the lysogenic Rabinowitz strain. The methylases of all the four strains methylated the adenine and cytosine residues of the acceptor DNA-forming 5-methyl-cytosine and 6-methyl-aminopurine. The mycobacterial DNAs were methylated by the corresponding mycobacterial methylases in vitro only to 25-30% as compared to the methylation on phage Sd-DNA. This is comparable with the low in vivo methylation of mycobacterial DNAs. The kinetics of methylation indicated a low non-specific nuclease content of the mycobacterium cells.

5-Methylcytosine↗
PubMed1982

Association between HLA B7, DR2 and dysfunction of natural- and antibody-mediated cytotoxicity without connection with the deficient interferon production in multiple sclerosis.

In this study, 133 patients with MS were investigated for HLA-A,B,C,DR antigens, natural killer (NK) cell activity, and antibody-mediated cytotoxicity (ADCC). A higher frequency of HLA B7 and DR2 was found in this group of patients than in the healthy control group, as can be observed in other caucasoid populations as well. In Gypsies living in the same geographic area, almost a complete absence of the disease was observed, corresponding to a lack of B7; however, HLA DR2 was present in 56% of this population. NK activity and ADCC measured against the K-562 tumor cell line was found to be significantly lower in MS patients, most pronounced in the group of male patients. Interferon augmentation of NK activity showed similar impairment in the patient group, and their lymphocytes produced a significantly lower amount of interferon. A correlation was demonstrated between both killer cell function and HLA B7, DR2 in MS patients, however, it was significant only in the case of ADCC and DR2. No other correlations were found in relation to interferon augmentation, interferon production, and HLA antigens. The above finding underscores a possible HLA-linked pathogenetic role of NK and K cell dysfunction in MS. This is consistent with other, similar observations that a possible defect in virus immunity may exist in MS patients.

Adult↗
PubMed1982

Methylated nucleic acid bases in Mycobacterium and mycobacteriophage DNA.

Methylated bases of the DNA of two mycobacteria (Mycobacterium phlei and Mycobacterium smegmatis var. butyricum) and two mycobacteriophages (Phage phlei and Phage butyricum) have been studied. In both the bacterial and the phage DNAs 5-methyl-cytosine and 6-methyl-aminopurine could be detected. Using L-(methyl-H3)-methionine as methyl donor not only the methylated bases of bacterium and phage DNA proved to be radioactive, but also the non-methylated purine residues and thymine. Possible pathways of this phenomenon are discussed.

5-Methylcytosine↗
PubMed1981

Double lysogeny of Mycobacterium smegmatis.

While the plating efficiency of mycobacteriophage butyricum (By) on Mycobacterium smegmatis strain Rabinowitz (M.sm.R.) cells is less than 10(-8), it proved to be 5 X 10(-1) on the lysogenic Mycobacterium smegmatis strain Rabinowitz (M.sm.R. [V72]) cells. Bacteriophage By forms plaques on M.sm.R. cells at a very low frequency; it can, however, adsorb to these cells in the same degree as to its original host. The average burst size of Mycobacterium smegmatis strain butyricum (M.sm.b.) cells infected with mycobacteriophage By is 60, and that of M.sm.R. (V72) superinfected with bacteriophage By is only 6. A double lysognic strain was isolated from M.sm.R. (V72) cells surviving By phage infection.

Adsorption↗
PubMed1980

A kinetic study of glucocorticoid-heparin interaction on the in vivo DNA-synthesis of mouse lymphatic organs.

The effect of glucocorticoids and heparin (in depot form) on the DNA-synthesis of thymus and spleen of mice was investigated by measuring (3H)dThd incorporation in a four day period. The kinetics of glucocorticoid action was similar whether the hormones were applied in 11 beta-hydroxy-, or keto-form and was characterized by a suppressive effect with a maximum on the first two days after administration. The suppressive effect of glucocorticoids proved to be more marked in the thymus than in the spleen. Heparin per se did not change thymidine incorporation into the lymphoid organs, but injected 3 hours prior steroid administration inhibited the suppressive effect of cortisone, but not that of hydrocortisone. In addition, heparin even reversed the suppressing effect of cortisone on splenic (3H)dThd uptake. The effects of heparin on glucocorticoid action could be only observed when the steroid was applied intraperitoneally. This observation and other data discussed suggest the involvement of peritoneal cells (macrophages) in glucocorticoid-heparin interactions on DNA-synthesis of lymphoid organs.

Animals↗
PubMed1980

Interactions of glucocorticoids and heparin on the humoral immune response of mice.

Interactions of glucocorticoids and heparin on the humoral immune response of mice to SRBC have been studied. Heparin injected subcutaneously in a depot-form 2 hours before immunization restores the antibody-forming ability of mice immuno-suppressed by hydrocortisone, through pretreatment of mice only with heparin 3 days before immunization decreases the PFC-count in the spleen. Cortisone (ip) and heparin (sc) per se injected at about the time of immunization with suboptimal doses of SRBC resulted only in a slight stimulating or no effect on spleen PFC count and serum antibody level. Cortisone and heparin applied in combination, however, exerted a stimulatory effect on the humoral immune response to SRBC. The route of steroid administration pointed to the significance of macrophages in this phenomenon. As the cooperative effect of heparin + cortisone on the humoral immune response shows a good correlation with their cooperative effect on in vivo (3H)dThd incorporation and thymidine kinase activity of spleen, it was hypothesized that an in vivo mitogenic activity for the spleen cells was responsible for the adjuvant effect observed.

Animals↗
PubMed1980

Dysfunction of natural killer cells in multiple sclerosis: a possible pathogenetic factor.

Natural killer (NK) cell activity, antibody-dependent cytotoxicity (ADCC) and the effect of interferon on NK activity was investigated in multiple sclerosis (MS) patients. NK activity measured against K-562 tumour cell line was found to be significantly low in MS patients, and this was most pronounced in the group of male patients with definitive disease. The response of NK cells to interferon proved to be impaired and almost no activation could be demonstrated in response to polyinosinic-polycytidylic acid (poly I:C). Preliminary data obtained by the determination of interferon production in several definitive MS cases reflect a defect in the interferon producing capacity of lymphocytes. The possible involvement of impaired NK cell function in the aetiopathogenesis of MS is discussed.

Adult↗
PubMed1980

Ultrastructure of extracellular matrix of embryonic chick limb bud cartilage.

The ultrastructure of the extracellular matrix of chick limb buds at stages 24--36 was investigated with the electron microscope and with polarization microscopic evaluation of topo-optical reactions. Two types of extracellular matrix structures could be distinguished. In the primary matrix of presumptive cartilaginous areas at developmental stage 25, topo-optical reactions revealed polycarboxylated glycosaminoglycans oriented parallel to the cell surface. With the electron microscope few fine filaments and small matrix granules could be found. In the secondary cartilage matrix, from stage 26 on, topo-optical reactions demonstrated glycosaminoglycans and collagen being predominantly ordered parallel to each other. Their amount and the degree of their orientation gradually increased during the developmental period investigated. Electron microscopy demonstrated collagen filaments and matrix granules in increasing number at stages 26--36. While some parallel ordering of filaments was seen in the electron micrographs, no sign of spatial ordering of glycosaminoglycans could be found with this technique.

Animals↗
PubMed1980

Teratogenic effect of 2'-thiourea in the rat.

The compound 2'-thiourea was studied for teratogenic effect in fetal rats. A 0.2% aqueous solution of 2'-thiourea (Merck) was administered ad libitum to pregnant rats from the first to the 14th day of pregnancy. The pregnancy was counted from the day when sperm was found in the vaginal smear. In the treated rat fetuses hypoplasia of the brain and spinal cord, internal hydrocephalus, hypoplasia of the spinal ganglia, kypholordosis, micromelia, micrognathia, cleft palate, retarded tooth development, exophthalmus, coloboma, and cataract were observed. In addition, generalized haemorrhages were found all over the body. The changes were similar to those produced by ethylene thiourea treatment in rat fetuses.

Animals↗
PubMed1979

Inhibition of cortisone action in mice by heparin.

A single dose of heparin applied in a depot-form (Freund's incomplete adjuvant or Ca-phosphate gel) inhibits the effects of intraperitoneally injected cortisone on the lymphoid organs (thymus and spleen), on the peritoneal and peripheral lymphoid cell count and serum gamma globulin level as well as on the liver glycogen deposition in mice. The same dose of heparin did not influence the action of hydrocortisone measured on the thymic and spleen involution and liver glycogen content. The route of cortisone administration seems to be critical, as heparin shows no or only minor effects when cortisone is applied subcutaneously; moreover, the action of cortisone per se is more marked by subcutaneous than by intraperitoneal administration. The results suggest the hypothesis that heparin inhibits cortisone-cortisol conversion and this inhibition is mediated by macrophages.

Animals↗
PubMed1978

Neoplastic response of turkey liver to MC29 leukosis virus.

Twelve to fourteen days after intravenous inoculation of MC29 virus (1 x 10(5)LD50) into 1-day-old turkeys, liver tumour developed in 100% of the infected animals and led to death of birds. The tumour proved to be hepatomas histologically and electron microscopically. Numerous C-type particles were detectable among the tumour cells, as well as budding from the cell membrane. C-type particles were also observed in the tumour-free liver tissue in the spaces between the cells, budding was not detectable. Large number of virus particles were found in spleen extracellularly and intracellular vacuoles. Kidney tumours did not develop, but a few extracellular virus particles were located in the tissue. The MC29 virus-induced primary liver tumour in the turkey seems to be a suitable model for the morphological study of the relationship between oncogenic viruses and eukaryotic cells.

Animals↗
PubMed1977

Analysis of thymidine kinase activity and glucocorticoid-binding capacity in the thymuses of healthy and tumor-bearing chickens.

Thymidine kinase activity in the lymphoid organs of healthy and tumor-bearing chickens was studied after hydrocortisone or dexamethasone treatment. Glucocorticoid hormones (10 mg/100 g body wt) administered twice in 48 hours resulted in an 80% decrease in thymidine kinase activity in the thymuses of healthy chickens, whereas birds with transplantable MC 29 chicken hepatoma failed to respond to the hormones. In the bursae of Fabricius of healthy or tumor-bearing chickens, thymidine kinase activity did not change considerably after administration of hydrocortisone or dexamethasone. The steroid-binding capacity in cellfree systems prepared from thymuses of tumor-bearing birds was significantly decreased. Thus the difference in steroid-binding capacity between thymuses of healthy and tumor-bearing chickens correlated well with, and could account for, the failure of hydrocortisone and dexamethasone to reduce the thymidine kinase level in tumor-bearing birds.

Animals↗