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Biomedical subjects

J Urban

Publications and source records attributed to J Urban.

At least 19 recordsLinked to original sources
PubMed1992

15gag proteinase of myeloblastosis-associated virus: specificity studies with substrate-based inhibitors.

The specificity of the proteinase of myeloblastosis-associated virus (MAV) was studied with (a) 21 substrate-based inhibitors, (b) 9 inhibitors with pseudopalindrome sequences, (c) 8 chimeric inhibitors, and (d) 3 compounds designed as human immunodeficiency virus 1 (HIV-1) proteinase inhibitors. The central inhibitory unit (transition state or cleaved bond analog) and the role of the inhibitor side chains from P4 to P4' were investigated. MAV proteinase prefers an aromatic side chain in P1 and a small aliphatic nonpolar chain in P2 and P2'. Residues in P5 and P4 positions are outside of the short catalytic cleft of the enzyme, but still influence binding considerably. The data obtained provide evidence that the MAV proteinase has generally lower specificity and poorer binding than the HIV proteinase.

Amino Acid Sequence↗
PubMed1992

[Folk healing causing severe diabetic coma].

The authors demonstrate on the case of a 21-year-old female diabetic (type I), who had been well compensated with insulin for five years, the life threatening procedure of a popular healer. By eliminating insulin he induced severe keto acidotic coma.

Adult↗
PubMed1992

Reduced-bond tight-binding inhibitors of HIV-1 protease. Fine tuning of the enzyme subsite specificity.

Truncation of a peptide substrate in the N-terminus and replacement of its scissile amide bond with a non-cleavable reduced bond results in a potent inhibitor of HIV-1 protease. A series of such inhibitors has been synthesized, and S2-S3' subsites of the protease binding cleft mapped. The S2 pocket requires bulky Boc or PIV groups, large aromatic Phe residues are preferred in P1 and P1' and Glu in P2'. The S3' pocket prefers Phe over small Ala or Val. Introduction of a Glu residue into the P2' position yields a tight-binding inhibitor of HIV-1 protease, Boc-Phe-[CH2-NH]-Phe-Glu-Phe-OMe, with a subnanomolar inhibition constant. The relevant peptide derived from the same amino acid sequence binds to the protease with a Ki of 110 nM, thus still demonstrating a good fit of the amino acid residues into the protease binding pockets and also the importance of the flexibility of P1-P1' linkage for proper binding. A new type of peptide bond mimetic, N-hydroxylamine -CH2-N(OH)-, has been synthesized. Binding of hydroxylamino inhibitor of HIV-1 protease is further improved with respect to reduced-bond inhibitor.

Amino Acid Sequence↗
PubMed1992

Mutagenic activity of copper(II) chromate and dichromate complexes with polypyridines.

Copper(II) chromate and dichromate complexes with 2,2'-bipyridyl and 1,10-phenathroline were tested for their mutagenic activity in the standard Ames test. All of six tested complexes exhibited markedly lower mutagenic activity than the reference compounds--potassium dichromate and sodium chromate. The blockage of Cr(VI) reduction capability in the presence of the complex Cu2+ ion and the competition between copper and chromium ions in the interaction with cellular components are discussed in the light of the results of our previous chemical study.

2,2'-Dipyridyl↗
PubMed1992

Resistance to Ascaris suum in parasite naïve and naturally exposed growers, finishers and sows.

Commercially reared growers, finishers, and sows of Danish Landrace x Yorkshire crossbred were inoculated orally with Ascaris suum at 50 eggs kg-1 body weight. White spots on the serosal surface of livers and total larval recoveries from lungs were recorded 7 days later. The response in pigs originating from a specific pathogen free and parasite free herd (parasite naïve) was observed in the three different age groups and compared with age-matched pigs from a herd maintained in a facility contaminated with A. suum (naturally exposed). The pre-inoculation immune status of the various groups was characterized serologically using antigen preparations derived from various stages of A. suum. Inoculation of all age groups of parasite naïve pigs with A. suum eggs produced relatively high liver white spots and lung larvae, although expression of these counts as a percentage of the inoculum showed a moderate age-related resistance from growers to finishers to sows. In contrast, pigs naturally exposed to A. suum expressed strong immunity to a challenge infection as few or no larvae were detected in the lungs. In addition, growers, finishers, and sows from the naturally exposed herd had significantly higher levels of serum IgG/IgA to several different A. suum antigens compared with pigs from the parasite nave herd. Liver white spots, expressed as a percentage of the inoculum, were highest in growers from the naturally exposed herd but were markedly reduced in finishers and sows from that herd. In fact, few or no white spots were observed in naturally exposed sows, while sows from the parasite-naïve herd had in excess of 300 liver white spots following challenge. These results indicate that commercially raised pigs that are exposed to A. suum develop a strong protective immunity that ultimately produces a complete pre-hepatic barrier to larval migration, while pigs raised parasite free remain susceptible to infection.

Age Factors↗
PubMed1992

Influence of the pH-value on the growth of Staphylococcus epidermidis, Staphylococcus aureus and Propionibacterium acnes in continuous culture.

A cutaneous isolate of Staphylococcus epidermidis, Staphylococcus aureus and Propionibacterium acnes was grown in continuous culture at varying pH-values ranging from 5.0 to 8.5. In terms of the specific growth rate as well as the bacterial density during the plateau phase there were remarkable differences. In particular, Propionibacterium acnes grew much better in the pH 6.0 to 7.0 range than in a more acidic or alkaline milieu. Staphylococcus epidermidis resembled Staphylococcus aureus showing no major difference at pH 5.5 and 7.0. These findings substantiate the hypothesis that minor changes of the pH in the pH 5.5 to pH 6.0 range as to be induced by chemically neutral or alkaline skin cleansers on the human skin surface can increase the number of propionibacteria but not staphylococci remarkably due to the relative alkalinity by itself.

Culture Media↗
PubMed1991

Purified Fc epsilon R+ bone marrow and splenic non-B, non-T cells are highly enriched in the capacity to produce IL-4 in response to immobilized IgE, IgG2a, or ionomycin.

Non-B, non-T cells from spleen and bone marrow cells produce IL-4 in response to cross-linkage of high affinity receptors for Fc epsilon R or Fc gamma RII, and to treatment with calcium ionophores. Cells bearing high affinity Fc epsilon R constituted 1 to 2% of non-B, non-T cells of spleen and of total bone marrow cells from naive donors. In mice whose immune systems had been polyclonally activated by injection with anti-IgD antibodies or had been infected with Nippostrongylus brasiliensis larvae, the frequency of Fc epsilon R+ cells in splenic non-B, non-T cells was also 1 to 2% but in bone marrow from anti-IgD-injected mice donors the frequency was approximately 5%. Cell sorting experiments revealed that all of the capacity to produce IL-4 in response to immobilized IgE or IgG2a or to ionomycin was found in the Fc epsilon R+ fraction. Among the Fc epsilon R+ spleen cells from naive donors, the frequency of IL-4-producing cells was 1/20 to 1/40 whereas in mice that had been injected with anti-IgD or infected with N. brasiliensis, the frequency of IL-4 producing cells in the Fc epsilon R+ population was approximately 1/5.

Animals↗
PubMed1991

Molecular cloning of gp 80, a glycoprotein complex secreted by kidney cells in vitro and in vivo. A link to the reproductive system and to the complement cascade.

cDNA clones coding for the gp 80 heterodimeric glycoprotein complex secreted constitutively at the apical surface of Madin-Darby canine kidney (MDCK) cells have been isolated from MDCK cDNA libraries in lambda gt11 and lambda gt10. The cloned sequences encode a polypeptide chain of 445 amino acids. The deduced amino acid sequence of the gp 80 protein reveals 80% homology to rat SGP-2, a major secretory protein of the testes epithelium and 83% homology to SP-40,40, a human complement-associated protein. SGP-2 and SP-40,40 have been proposed to be serum and seminal forms of the same protein. The sequence homology as well as the results of Southern and Northern blot analyses and immunological studies suggest that gp 80 is the canine homolog of the rat SGP-2 and the human SP-40,40. The protein is expressed in the embryonic kidney already early during organogenesis. In the adult kidney the protein has been localized along the luminal surfaces of the proximal and distal tubule and the collecting duct cells.

Amino Acid Sequence↗
PubMed1991

Increased frequency of interleukin 4-producing T cells as a result of polyclonal priming. Use of a single-cell assay to detect interleukin 4-producing cells.

A limiting dilution assay capable of detecting interleukin 4 (IL4) production by a single cell has been developed. This assay is based on the stimulation of T cells, in the presence of IL2 (5 U/ml), with anti-CD3 antibody bound to the surface of Terasaki wells. Cells of the IL4-selective indicator line, CT.4S, are added 24-36 h later and IL4 production is determined based on their survival 24-48 h thereafter. A frequency of 0.98 was obtained for IL4 production by T cells of the D10.G4 cell line. T cells from naive donors capable of producing IL4 in response to anti-CD3 plus IL2 were quite rare, with a frequency in four experiments ranging between 0.0003 and 0.0018. Treatment of mice with polyclonal activators known to increase the IL 4-producing capacity of T cells when assayed in bulk culture caused striking increases in the frequency of IL4-producing cells. Similarly, culturing cells in vitro with anti-CD3, IL2 and IL4 for 5 days caused a marked increase in the frequency of cells capable of producing IL4, to 0.031.IL4 production by individual T cells is dependent upon IL2. Thus, in naive T cell populations, the frequency of IL4-producing cells in response to stimulation with anti-CD3 in the absence of IL2 was below the limit of detection. T cells from primed donors showed a striking inhibition in the frequency of IL4-producing cells in response to anti-CD3 when IL2 was not present. The availability of a simple assay to measure the frequency of cells capable of producing IL4 should have substantial utility in allowing the evaluation of conditions that regulate IL4 production in vivo and in vitro.

Animals↗
PubMed1990

Cord blood triglyceridemia in cases of placental insufficiency.

Cord blood triglyceride concentration increased in cases of placental insufficiency. The significant relationship has been found between elevated triglyceride, decreased Apgar score, and low pH values. We suggest that the measurement of cord blood triglyceridemia might be used as a valuable indicator of chronic fetal distress.

Apgar Score↗
PubMed1990

[Contribution of the treatment of discoloured teeth].

New dental materials and their combinations increase the aesthetic and functional quality of treatment. A great improvement in the aesthetic treatment of discoloured teeth is the use of dental ceramic combined with composites.

Ceramics↗
PubMed1990

[Weight reduction in obese patients in the early period after myocardial infarct].

During the early rehabilitation stage to 27 obese subjects after a non-complicated myocardial infarction a low energy diet was administered (2 and 5 MJ resp.--19 patients) or diet no. 7 or 9 (9 and 6 MJ--8 patients). The regime was started on average 8.4 days (at least 5 days) after the acute attack, its tolerance was satisfactory, there were no complications. In the group with a markedly low energy diet the cholesterol and total lipid levels declined. The body weight declined in both groups. It was revealed that early body weight reduction in obese subjects with non-complicated myocardial infarction involves no risk and the hospitalization period can be effectively used also as introduction to the regime in secondary prevention of ischaemic heart disease.

Diet, Reducing↗
PubMed1989

Umbilical cord gamma-glutamyl transpeptidase and placental dysfunction.

Placental dysfunction has been suspected if human placental lactogen level and/or cystine-aminopeptidase activity were lower than 10th centile. Significant rise in gamma-glutamyl transpeptidase (GGTP) has been found in samples of arterial cord blood of newborns born to mothers with placental insufficiency. We observed the relationship between GGTP activity and decrease in cord pH and lower Apgar score of corresponding infants. We suggest that chronic hypoxemia as a consequence of placental dysfunction may result in damage of fetal liver cells.

Apgar Score↗
PubMed1979

A rat serum glycoprotein whose synthesis rate increases greatly during inflammation.

Crossed immunoelectrophoresis of rat serum demonstrated considerably increased serum concentrations of at least ten different proteins during turpentine-induced inflammation. One protein, which moved during electrophoresis like an alpha 1 globulin, showed a particularly large increase. This protein was purified to homogeneity by ammonium sulfate fractionation followed by chromatography on DEAE-cellulose. Sephadex G-100, and concanavalin A-Sepharose, and finally disc electrophoresis in polyacrylamide gel. It has a molecular weight of 56,000 determined by equilibrium ultracentrifugation. An apparent molecular weight of 68,000 was estimated for the reduced protein by electrophoresis in polyacrylamide gel plus sodium dodecyl sulfate, suggesting that the native protein is composed of a single polypeptide chain. It has an E2801%, 1 cm of 5.2, an isoelectric pH of 4.7, and contains 19% carbohydrate. The protein does not inhibit bovine trypsin or chymotrypsin. Its physical properties and amino acid composition distinguish this protein from all other rat serum proteins hitherto characterized. During acute inflammation, induced 25 h previously, rats incorporated 20 times more [14C]leucine into this particular protein than did normal rats. However, incorporation into total serum protein during acute inflammation increased only slightly. Regardless of whether inflammation was induced by surgical injury or by a subcutaneous turpentine injection, within 48 h the serum concentration of this major acute-phase protein rose from the normal value of 0.46 g/liter to a maximum value of 7.2 g/liter, which constituted 10% of the total serum protein.

Alpha-Globulins↗
PubMed1979

Sister-chromatid exchanges and chromosal breakage in patients treated with cytostatics.

The frequency of structural chromosomal rearrangements and sister-chromatid exchanges (SCEs) was investigated in short-term phytohemagglutininstimulated lymphocyte cultures by means of bromodeoxyuridine substitution and fluorescence plus Giemsa (FPG) staining technique. Both these parameters were significantly increased in patients treated with comparatively low doses of cyclophosphamide, busulphan and adriamycin. The increased SCE rate was proportional to the number of chromosome breaks, the ratio of SCE to breaks being about 100:1. The increase in the SCE number was maintained for several months after the termination of cytostatic therapy, when the conventional analysis of chromosome breaks yielded normal results. Normal SCE values were obtained in two patients treated with low doses of fluorouracil.

Bromodeoxyuridine↗
PubMed1979

Relationship between protein synthesis and secretion in liver cells and the state of the adenine nucleotide system.

Adenine nucleotide levels could be precisely and reproducibly adjusted in liver cell suspensions by partially depleting the ATP pool with D-fructose or glycerol. Thus, it was possible to quantitatively correlate rates of protein synthesis and secretion with intracellular levels of ATP and with derived parameters, such as the adenylate energy charge. Half the maximum rate of incorporation of leucine into protein was observed at an energy charge of 0.80, a ratio of ATP to ADP of 2.6, and an ATP level of 1.05 mumol per g of wet cells. Proteins were secreted with half the maximum rate at an energy charge of 0.85, a ratio of ATP to ADP of 3.1 and an ATP concentration of 1.1 mumol per g of wet cells. Protein secretion did not depend on continued synthesis. Inhibitors of oxidative phosphorylation inhibited protein secretion in addition to protein synthesis, in contrast to observations by other authors on liver slices.

Adenine Nucleotides↗