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Biomedical subjects

O Mach

Publications and source records attributed to O Mach.

At least 19 recordsLinked to original sources
PubMed1990

Immunoregulatory effect of a synthetic peptide corresponding to a region of protein p24 of HIV.

The effect of a synthetic peptide, corresponding to a sequence of HIV-1 p24 protein (amino acids 218-237), on in vitro immune responses was studied. The peptide inhibited in a dose-dependent manner the induction of an anti-SRC antibody response and of a PPD-specific proliferative response of human PBL. On the other hand, PHA-induced proliferation of human PBL and PPD-induced proliferation of a PPD-specific human T-cell line were not modified by comparable amounts of the peptide. These results suggest that structures from a protein (p24), present in the serum throughout the course of HIV infection, are able to interfere with the inductive stages of specific immune responses. These findings may help to unravel some of the pathogenic mechanisms of AIDS and may contribute to the development of vaccine strategies.

Animals↗
PubMed1989

Multiple continuous-flow solid-phase peptide synthesis. Synthesis of an HIV antigenic peptide and its omission analogues.

Multiple continuous-flow solid-phase peptide synthesis was performed on a standard polystyrene-based resin under low-pressure conditions using a simple manually operated synthesizer. Stable-flow resin-packed columns were prepared in small polypropylene flow reactors, adjustable for volume. The concurrent synthesis of 10 peptides was carried out in flow reactors concatenated together; solvents and reactants were passed through this set of columns using moderate overpressure. One decapeptide, H-Val-Tyr-Tyr-Arg-Asp-Ser-Arg-Asn-Pro-Leu-NH2, containing an antigenic determinant of the p31 protein product of the pol gene of the human immunodeficiency virus, and its nine omission analogues were synthesized.

HIV Antigens↗
PubMed1989

Solid phase enzyme immunoassay of human interleukin 2 utilizing antibodies against synthetic IL-2 peptides.

In the present study, solid phase enzyme immunoassay utilizing antibodies against synthetic IL-2 peptides was used for quantitative measurements of human recombinant and lymphoid IL-2 preparations. The 27-peptide MCF-III-6 (Leu-Glu-His-Leu-Leu-Leu-Asp-Leu-Gln-Met-Ile-Leu-Asn-Gly-Ile-Asn-Asn-- Tyr-Lys-Asn-Pro-Lys-Leu-Thr-Arg-Met-Leu) that comprises the region 14-40 from the IL-2 amino acid sequence was synthesized and used for immunization of rabbits. Resulting anti-MCF-III-6 polyvalent rabbit antibodies reacted specifically in EIA up to dilution of 10(-7) with the MCF-III-6 peptide used for immunization as well as with 16-peptide I-16 (Cys-Nle-Gly-Ile-Asn-Asn-Tyr-Lys-Asn-Pro-Lys-Leu-Thr-Arg-Met-Leu) that comprises the region 27-40 from the IL-2 amino acid sequence. The anti-MCF-III-6 antibody reacted also with human recombinant IL-2 preparations obtained from three producers (Cetus, Riga and Amersham), to the concentration of 0.1 ng/ml, and with various human lymphoid IL-2 preparations. Direct correlation was observed between quantitative measurements of human lymphoid IL-2 by EIA and by CTLL bioassay. It can be concluded that utilization of synthetic IL-2 peptides provides a suitable and comparatively unexpensive immunogen for the production of IL-2 antibodies and that the solid phase EIA using such antibodies can be employed as a rapid, reproducible, and sensitive method for quantitative examination of both recombinant and lymphoid IL-2 preparations.

Amino Acid Sequence↗
PubMed1989

[Our approach to the care of chronic instability of the knee joint].

Chronic instability of the knee joint is a serious problem for the affected patient and the attending physician. Diagnosis must reveal which structures of the soft knee are insufficient. We use as a basis in particular a detailed clinical examination which frequently must be made under short-term general anaesthesia. As to auxiliary examination methods, we recommend X-rays in forced positions, possibly arthroscopy. Defects of the cruciate ligaments can be evaluated well also by means of computed tomography. Operation should be indicated carefully. We consider the extent of the patient's complaints, the ability of dynamic compensation of the instability, the presence of exudates, haematomas, signs of arthritis, locomotor restrictions and, last not least, also the assumed ability of the patient to cooperate in rehabilitation. In surgical treatment of instabilities it is necessary to respect carefully biomechanical principles of the function of the knee joint. In prostheses of the cruciate ligaments we prefer direct reconstruction with an autologous graft to extraarticular operations. It seems that in older patients also reconstruction with synthetic ligaments will be feasible.

Adult↗
PubMed1987

Computer prediction of potential immunogenic determinants from protein amino acid sequence.

In proteins, immunogenic determinants that can induce protein-reactive antipeptide antibodies reside mostly in those parts of the molecule that have a high tendency to form beta-turns. A program for an IBM personal computer which predicts protein immunogenic determinants is described. The program predicts potential immunogenic determinants from protein amino acid sequences according to a Chou-Fasman-based probability of a beta-turn occurrence, p greater than 1.5 X 10(-4)(P. Y. Chou and G. D. Fasman, 1978, Adv. Enzymol. 47, 46-148). Oncopeptides (whose efficacy in generating protein-reactive antipeptide antibodies has been described) with a beta-turn probability of p greater than 1.5 X 10(-4) elicited antipeptide antibodies that reacted with the parent oncoprotein at a rate of 96%, thus showing a surprisingly good correlation between the tendency to form a beta-turn and the protein reactivity of antipeptide antibodies. Potential immunogenic determinants were predicted on myohemerythrin and myoglobin.

Amino Acid Sequence↗
PubMed1986

Virus-specific nucleotide sequences in duck cells transformed by chicken and duck-adapted Rous sarcoma virus.

Adaptation of PR-RSV-C on duck cells results in successful and efficient replication of the adapted virus in duck cells. The adapted variant, daPR-RSV-C, was compared with the parental chicken-cell derived PR-RSV-C. No differences in the efficiency of integration and in the number of integrated proviral copies in duck cells were found. However, the structure of proviral DNA of the adapted virus was different. Whereas EcoRI and HindIII digestion showed no differences between chicken-cell derived PR-RSV-C and the daPR-RSV-C, a new restriction site was found for BamHI endonuclease, which is probably located at the 3' end of the env gene.

Adaptation, Physiological↗
PubMed1986

The presence of retroviral particles in hybridoma cell lines.

The presence of very high numbers of type C and type A retroviral particles was repeatedly confirmed not only in myeloma cells NSI, Ag 8 and in thymoma cells BW5147, EL 4 but also in B and T cell hybridomas constructed from the myeloma and thymoma cells used. Retroviral particles were demonstrated by current electron-microscopic and physicochemical methods. Biological tests for the induction of possible malignant or any pathological changes in the artificially infected sensitive cells during long-term cultivations in vitro or in vivo gave negative results. Nevertheless, on account of the hitherto unknown action of retroviruses one can suppose that monoclonal products from B and T cell hybridomas, particularly when used for practical purposes, should be purified because of their infectious nature.

Animals↗
PubMed1986

An enzyme-linked immunosorbent assay for detecting the chicken B cells.

Two modifications of an indirect enzyme immunoassay described here allow the discernment of chicken B and T cells when a polyclonal rabbit anti-chicken Ig antibody or a monoclonal antibody reactive with chicken IgM and IgG heavy chains is used. Comparison of both types of antibody in ELISA and in indirect immunofluorescence suggests that they can readily be exploited for detection of lymphoid cells with surface immunoglobulin markers.

Animals↗
PubMed1985

Tumour inhibitory effects of TCGF/IL-2/-containing preparations.

Supernatants from ConA-stimulated rat spleen cell cultures and from cultures of PMA-stimulated murine lymphoma subline EL-4TF were found to contain TCGF and to inhibit growth of a transplantable, MC-induced sarcoma MC11 in syngeneic mice. Tumour-inhibitory effects of the supernatants were dependent on local and repeated administration. Prior to use of the supernatants obtained from PMA-stimulated EL-4TF cell cultures, the dialysable PMA had to be removed; contamination with PMA was found to abolish the tumour-inhibitory effect of the supernatants and to produce enhancement of tumour growth. A significant tumour-inhibitory effect has also been obtained with partially purified TCGF prepared from culture supernatants of cloned EL-4TF cells by ammonium sulphate precipitation, ion-exchange (FPLC) chromatography, and AcA 44 Ultrogel filtration.

Animals↗
PubMed1983

Antiviral and anticellular effects of synthetic (2'-5')-oligoadenylate (A 2' p 5' A 2' p 5' A) in Rauscher murine leukaemia.

Antiviral and antileukaemic effects of the synthetic (2'-5')-oligoadenylate trimer [(2'-5')-ApApA] were demonstrated in BALB/c mice infected with Rauscher murine leukaemia virus (RMLV) by intraperitoneal (i.p.) treatment for 5-20 days (100 micrograms--1 mg daily doses) as evidenced by 72% suppression of viraemia and by decreased activity of serum reverse transcriptase levels. Electron microscopy revealed more than 95% inhibition of RMLV replication as compared to controls in transformed spleen cells from mice treated 5 times with 1 mg dose of (2'-5') ApApA. A significant and dose-dependent reduction of spleen weights of the RMLV-infected mice treated with (2'-5') ApApA was also observed. The antileukaemic effect of (2'-5-') ApApA was enhanced by simultaneous i.p. injection of amphotericin B (20 micrograms/mouse). In comparison to the effect of interferon (IFN) on RNA tumour viruses, our results suggest a higher antiviral activity of the synthetic (2'-5') ApApA oligonucleotide in suppressing RMLV replication in vivo.

Adenine Nucleotides↗
PubMed1983

T-cell hybrids. IV. One of parental cell lines is dominant in determining membrane characteristics of hybrid cells.

Membrane characteristics of parental thymic lymphoma cells (BW5147, EL-4R) and their hybrids (BH2) derived by PEG-promoted cell fusion were compared. Isoelectric focusing of the cell populations, titration of membrane proton binding groups and quantitative examination of cell-substrate adhesiveness indicated that the BW5147 cells behaved as dominant in determining cell membrane characteristics of the BH2 hybrids.

Animals↗
PubMed1981

Attempts ot activate endogenous virus expression with Marek's disease virus DNA.

Several DNAs derived from Marek's disease virus-infected cells and tissues were tested for in vitro infectivity and for the ability to activate avian endogenous type C virus. The DNA isolated from tumour tissue, peripheral blood buffy coat cells, MDV-infected tissue cultures, lymphoblastoid cell lines and feather follicle epithelium cells from MDV-infected birds elicited a negative response in transfection assays. The MDV DNAs isolated did not activate the endogenous type C virus from cell cultures derived from the C, I and M chicken lines. Activation was observed only in one experiment in the early period after transfection with MDV DNA. The treatment with DNase destroyed this MDV DNA activity, and lambda phage DNA and cell DNAs did not activate the endogenous viruses. Repeated experiments failed to confirm the early activation of endogenous viruses.

Animals↗
PubMed1981

Establishment and characterization of permanent cell lines from patients with acute and hairy cell leukemia.

Four cell lines were established from peripheral blood of patients with leukemia. All lines express the Epstein--Barr virus nuclear antigen (EBNA) and therefore should be classified as lymphoblastoid cell lines. However, one of the lines UHKT-5 established from a patient with acute myelomonocytic leukemia has some features not typical for lymphoblastoid cell lines. The cells resemble to macrophages with the phagocytic ability for yeasts, strong alpha-naphthylacetate esterase positivity in phagocytizing cells and unusually long villi. Another line UHKT-7 established from a patient with hairy cell leukemia expresses the same isotype of membrane immunoglobulins as the original hairy cells.

Adult↗
PubMed1979

The influence of host adaptation of Rous sarcoma virus on the transfecting activity of its DNA provirus.

Mammalian cells transformed with either Prague strain Rous sarcoma virus of subgroup C (XC cells) or Schmidt-Ruppin strain Rous sarcoma virus of subgroup D (RSCH cells) yielded virus upon fusion with chick cells. Virus was also rescued by transfection of DNA from these cells on to chick cells. However, virus rescue did not occur upon transfection of duck cells, and fusion with duck cells led to virus rescue only from RSCH and not from XC cells. To investigate this restriction on the duck cells the non-defective Prague strain of Rous sarcoma virus of subgroup C (PR-RSV-C) was adapted for efficient replication in duck embryo cells (daPR-RSV-C) by long-term passage in vitro. However, a second PR-RSV-C isolate, rescued from the rat XC sarcoma line (XC DNA 940 virus), failed to adapt to growth in duck cells. When transformed with daPR-RSV-C, which replicates in duck cells as well as in brown leghorn embryo (BLEF) cells, duck cells yielded DNA which transfects fresh duck cells, in contrast to DNA isolated from chicken or duck cells transformed with parental PR-RSV-C.

Animals↗